FreeBSD kernel kern code
sched_ule.c
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1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2002-2007, Jeffrey Roberson <jeff@freebsd.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice unmodified, this list of conditions, and the following
12 * disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/*
30 * This file implements the ULE scheduler. ULE supports independent CPU
31 * run queues and fine grain locking. It has superior interactive
32 * performance under load even on uni-processor systems.
33 *
34 * etymology:
35 * ULE is the last three letters in schedule. It owes its name to a
36 * generic user created for a scheduling system by Paul Mikesell at
37 * Isilon Systems and a general lack of creativity on the part of the author.
38 */
39
40#include <sys/cdefs.h>
41__FBSDID("$FreeBSD$");
42
43#include "opt_hwpmc_hooks.h"
44#include "opt_sched.h"
45
46#include <sys/param.h>
47#include <sys/systm.h>
48#include <sys/kdb.h>
49#include <sys/kernel.h>
50#include <sys/ktr.h>
51#include <sys/limits.h>
52#include <sys/lock.h>
53#include <sys/mutex.h>
54#include <sys/proc.h>
55#include <sys/resource.h>
56#include <sys/resourcevar.h>
57#include <sys/sched.h>
58#include <sys/sdt.h>
59#include <sys/smp.h>
60#include <sys/sx.h>
61#include <sys/sysctl.h>
62#include <sys/sysproto.h>
63#include <sys/turnstile.h>
64#include <sys/umtxvar.h>
65#include <sys/vmmeter.h>
66#include <sys/cpuset.h>
67#include <sys/sbuf.h>
68
69#ifdef HWPMC_HOOKS
70#include <sys/pmckern.h>
71#endif
72
73#ifdef KDTRACE_HOOKS
74#include <sys/dtrace_bsd.h>
75int __read_mostly dtrace_vtime_active;
76dtrace_vtime_switch_func_t dtrace_vtime_switch_func;
77#endif
78
79#include <machine/cpu.h>
80#include <machine/smp.h>
81
82#define KTR_ULE 0
83
84#define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX)))
85#define TDQ_NAME_LEN (sizeof("sched lock ") + sizeof(__XSTRING(MAXCPU)))
86#define TDQ_LOADNAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1 + sizeof(" load"))
87
88/*
89 * Thread scheduler specific section. All fields are protected
90 * by the thread lock.
91 */
92struct td_sched {
93 struct runq *ts_runq; /* Run-queue we're queued on. */
94 short ts_flags; /* TSF_* flags. */
95 int ts_cpu; /* CPU that we have affinity for. */
96 int ts_rltick; /* Real last tick, for affinity. */
97 int ts_slice; /* Ticks of slice remaining. */
98 u_int ts_slptime; /* Number of ticks we vol. slept */
99 u_int ts_runtime; /* Number of ticks we were running */
100 int ts_ltick; /* Last tick that we were running on */
101 int ts_ftick; /* First tick that we were running on */
102 int ts_ticks; /* Tick count */
103#ifdef KTR
104 char ts_name[TS_NAME_LEN];
105#endif
106};
107/* flags kept in ts_flags */
108#define TSF_BOUND 0x0001 /* Thread can not migrate. */
109#define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */
110
111#define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0)
112#define THREAD_CAN_SCHED(td, cpu) \
113 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask)
114
115_Static_assert(sizeof(struct thread) + sizeof(struct td_sched) <=
116 sizeof(struct thread0_storage),
117 "increase struct thread0_storage.t0st_sched size");
118
119/*
120 * Priority ranges used for interactive and non-interactive timeshare
121 * threads. The timeshare priorities are split up into four ranges.
122 * The first range handles interactive threads. The last three ranges
123 * (NHALF, x, and NHALF) handle non-interactive threads with the outer
124 * ranges supporting nice values.
125 */
126#define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1)
127#define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2)
128#define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE)
129
130#define PRI_MIN_INTERACT PRI_MIN_TIMESHARE
131#define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1)
132#define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE)
133#define PRI_MAX_BATCH PRI_MAX_TIMESHARE
134
135/*
136 * Cpu percentage computation macros and defines.
137 *
138 * SCHED_TICK_SECS: Number of seconds to average the cpu usage across.
139 * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across.
140 * SCHED_TICK_MAX: Maximum number of ticks before scaling back.
141 * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results.
142 * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count.
143 * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks.
144 */
145#define SCHED_TICK_SECS 10
146#define SCHED_TICK_TARG (hz * SCHED_TICK_SECS)
147#define SCHED_TICK_MAX (SCHED_TICK_TARG + hz)
148#define SCHED_TICK_SHIFT 10
149#define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT)
150#define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz))
151
152/*
153 * These macros determine priorities for non-interactive threads. They are
154 * assigned a priority based on their recent cpu utilization as expressed
155 * by the ratio of ticks to the tick total. NHALF priorities at the start
156 * and end of the MIN to MAX timeshare range are only reachable with negative
157 * or positive nice respectively.
158 *
159 * PRI_RANGE: Priority range for utilization dependent priorities.
160 * PRI_NRESV: Number of nice values.
161 * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total.
162 * PRI_NICE: Determines the part of the priority inherited from nice.
163 */
164#define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN)
165#define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2)
166#define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF)
167#define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF)
168#define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1)
169#define SCHED_PRI_TICKS(ts) \
170 (SCHED_TICK_HZ((ts)) / \
171 (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE))
172#define SCHED_PRI_NICE(nice) (nice)
173
174/*
175 * These determine the interactivity of a process. Interactivity differs from
176 * cpu utilization in that it expresses the voluntary time slept vs time ran
177 * while cpu utilization includes all time not running. This more accurately
178 * models the intent of the thread.
179 *
180 * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate
181 * before throttling back.
182 * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time.
183 * INTERACT_MAX: Maximum interactivity value. Smaller is better.
184 * INTERACT_THRESH: Threshold for placement on the current runq.
185 */
186#define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT)
187#define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT)
188#define SCHED_INTERACT_MAX (100)
189#define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2)
190#define SCHED_INTERACT_THRESH (30)
191
192/*
193 * These parameters determine the slice behavior for batch work.
194 */
195#define SCHED_SLICE_DEFAULT_DIVISOR 10 /* ~94 ms, 12 stathz ticks. */
196#define SCHED_SLICE_MIN_DIVISOR 6 /* DEFAULT/MIN = ~16 ms. */
197
198/* Flags kept in td_flags. */
199#define TDF_PICKCPU TDF_SCHED0 /* Thread should pick new CPU. */
200#define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */
201
202/*
203 * tickincr: Converts a stathz tick into a hz domain scaled by
204 * the shift factor. Without the shift the error rate
205 * due to rounding would be unacceptably high.
206 * realstathz: stathz is sometimes 0 and run off of hz.
207 * sched_slice: Runtime of each thread before rescheduling.
208 * preempt_thresh: Priority threshold for preemption and remote IPIs.
209 */
210static u_int __read_mostly sched_interact = SCHED_INTERACT_THRESH;
211static int __read_mostly tickincr = 8 << SCHED_TICK_SHIFT;
212static int __read_mostly realstathz = 127; /* reset during boot. */
213static int __read_mostly sched_slice = 10; /* reset during boot. */
214static int __read_mostly sched_slice_min = 1; /* reset during boot. */
215#ifdef PREEMPTION
216#ifdef FULL_PREEMPTION
217static int __read_mostly preempt_thresh = PRI_MAX_IDLE;
218#else
219static int __read_mostly preempt_thresh = PRI_MIN_KERN;
220#endif
221#else
222static int __read_mostly preempt_thresh = 0;
223#endif
224static int __read_mostly static_boost = PRI_MIN_BATCH;
225static int __read_mostly sched_idlespins = 10000;
226static int __read_mostly sched_idlespinthresh = -1;
227
228/*
229 * tdq - per processor runqs and statistics. All fields are protected by the
230 * tdq_lock. The load and lowpri may be accessed without to avoid excess
231 * locking in sched_pickcpu();
232 */
233struct tdq {
234 /*
235 * Ordered to improve efficiency of cpu_search() and switch().
236 * tdq_lock is padded to avoid false sharing with tdq_load and
237 * tdq_cpu_idle.
238 */
239 struct mtx_padalign tdq_lock; /* run queue lock. */
240 struct cpu_group *tdq_cg; /* Pointer to cpu topology. */
241 volatile int tdq_load; /* Aggregate load. */
242 volatile int tdq_cpu_idle; /* cpu_idle() is active. */
243 int tdq_sysload; /* For loadavg, !ITHD load. */
244 volatile int tdq_transferable; /* Transferable thread count. */
245 volatile short tdq_switchcnt; /* Switches this tick. */
246 volatile short tdq_oldswitchcnt; /* Switches last tick. */
247 u_char tdq_lowpri; /* Lowest priority thread. */
248 u_char tdq_owepreempt; /* Remote preemption pending. */
249 u_char tdq_idx; /* Current insert index. */
250 u_char tdq_ridx; /* Current removal index. */
251 int tdq_id; /* cpuid. */
252 struct runq tdq_realtime; /* real-time run queue. */
253 struct runq tdq_timeshare; /* timeshare run queue. */
254 struct runq tdq_idle; /* Queue of IDLE threads. */
255 char tdq_name[TDQ_NAME_LEN];
256#ifdef KTR
257 char tdq_loadname[TDQ_LOADNAME_LEN];
258#endif
259} __aligned(64);
260
261/* Idle thread states and config. */
262#define TDQ_RUNNING 1
263#define TDQ_IDLE 2
264
265#ifdef SMP
266struct cpu_group __read_mostly *cpu_top; /* CPU topology */
267
268#define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000))
269#define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity))
270
271/*
272 * Run-time tunables.
273 */
274static int rebalance = 1;
275static int balance_interval = 128; /* Default set in sched_initticks(). */
276static int __read_mostly affinity;
277static int __read_mostly steal_idle = 1;
278static int __read_mostly steal_thresh = 2;
279static int __read_mostly always_steal = 0;
280static int __read_mostly trysteal_limit = 2;
281
282/*
283 * One thread queue per processor.
284 */
285static struct tdq __read_mostly *balance_tdq;
286static int balance_ticks;
287DPCPU_DEFINE_STATIC(struct tdq, tdq);
288DPCPU_DEFINE_STATIC(uint32_t, randomval);
289
290#define TDQ_SELF() ((struct tdq *)PCPU_GET(sched))
291#define TDQ_CPU(x) (DPCPU_ID_PTR((x), tdq))
292#define TDQ_ID(x) ((x)->tdq_id)
293#else /* !SMP */
294static struct tdq tdq_cpu;
295
296#define TDQ_ID(x) (0)
297#define TDQ_SELF() (&tdq_cpu)
298#define TDQ_CPU(x) (&tdq_cpu)
299#endif
300
301#define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type))
302#define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t)))
303#define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f))
304#define TDQ_TRYLOCK(t) mtx_trylock_spin(TDQ_LOCKPTR((t)))
305#define TDQ_TRYLOCK_FLAGS(t, f) mtx_trylock_spin_flags(TDQ_LOCKPTR((t)), (f))
306#define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t)))
307#define TDQ_LOCKPTR(t) ((struct mtx *)(&(t)->tdq_lock))
308
309static void sched_priority(struct thread *);
310static void sched_thread_priority(struct thread *, u_char);
311static int sched_interact_score(struct thread *);
312static void sched_interact_update(struct thread *);
313static void sched_interact_fork(struct thread *);
314static void sched_pctcpu_update(struct td_sched *, int);
315
316/* Operations on per processor queues */
317static struct thread *tdq_choose(struct tdq *);
318static void tdq_setup(struct tdq *, int i);
319static void tdq_load_add(struct tdq *, struct thread *);
320static void tdq_load_rem(struct tdq *, struct thread *);
321static __inline void tdq_runq_add(struct tdq *, struct thread *, int);
322static __inline void tdq_runq_rem(struct tdq *, struct thread *);
323static inline int sched_shouldpreempt(int, int, int);
324void tdq_print(int cpu);
325static void runq_print(struct runq *rq);
326static void tdq_add(struct tdq *, struct thread *, int);
327#ifdef SMP
328static struct thread *tdq_move(struct tdq *, struct tdq *);
329static int tdq_idled(struct tdq *);
330static void tdq_notify(struct tdq *, struct thread *);
331static struct thread *tdq_steal(struct tdq *, int);
332static struct thread *runq_steal(struct runq *, int);
333static int sched_pickcpu(struct thread *, int);
334static void sched_balance(void);
335static int sched_balance_pair(struct tdq *, struct tdq *);
336static inline struct tdq *sched_setcpu(struct thread *, int, int);
337static inline void thread_unblock_switch(struct thread *, struct mtx *);
338static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS);
339static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb,
340 struct cpu_group *cg, int indent);
341#endif
342
343static void sched_setup(void *dummy);
344SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL);
345
346static void sched_initticks(void *dummy);
347SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks,
348 NULL);
349
350SDT_PROVIDER_DEFINE(sched);
351
352SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *",
353 "struct proc *", "uint8_t");
354SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *",
355 "struct proc *", "void *");
356SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *",
357 "struct proc *", "void *", "int");
358SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *",
359 "struct proc *", "uint8_t", "struct thread *");
360SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int");
361SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *",
362 "struct proc *");
363SDT_PROBE_DEFINE(sched, , , on__cpu);
364SDT_PROBE_DEFINE(sched, , , remain__cpu);
365SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *",
366 "struct proc *");
367
368/*
369 * Print the threads waiting on a run-queue.
370 */
371static void
372runq_print(struct runq *rq)
373{
374 struct rqhead *rqh;
375 struct thread *td;
376 int pri;
377 int j;
378 int i;
379
380 for (i = 0; i < RQB_LEN; i++) {
381 printf("\t\trunq bits %d 0x%zx\n",
382 i, rq->rq_status.rqb_bits[i]);
383 for (j = 0; j < RQB_BPW; j++)
384 if (rq->rq_status.rqb_bits[i] & (1ul << j)) {
385 pri = j + (i << RQB_L2BPW);
386 rqh = &rq->rq_queues[pri];
387 TAILQ_FOREACH(td, rqh, td_runq) {
388 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n",
389 td, td->td_name, td->td_priority,
390 td->td_rqindex, pri);
391 }
392 }
393 }
394}
395
396/*
397 * Print the status of a per-cpu thread queue. Should be a ddb show cmd.
398 */
399void
400tdq_print(int cpu)
401{
402 struct tdq *tdq;
403
404 tdq = TDQ_CPU(cpu);
405
406 printf("tdq %d:\n", TDQ_ID(tdq));
407 printf("\tlock %p\n", TDQ_LOCKPTR(tdq));
408 printf("\tLock name: %s\n", tdq->tdq_name);
409 printf("\tload: %d\n", tdq->tdq_load);
410 printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt);
411 printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt);
412 printf("\ttimeshare idx: %d\n", tdq->tdq_idx);
413 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx);
414 printf("\tload transferable: %d\n", tdq->tdq_transferable);
415 printf("\tlowest priority: %d\n", tdq->tdq_lowpri);
416 printf("\trealtime runq:\n");
417 runq_print(&tdq->tdq_realtime);
418 printf("\ttimeshare runq:\n");
419 runq_print(&tdq->tdq_timeshare);
420 printf("\tidle runq:\n");
421 runq_print(&tdq->tdq_idle);
422}
423
424static inline int
425sched_shouldpreempt(int pri, int cpri, int remote)
426{
427 /*
428 * If the new priority is not better than the current priority there is
429 * nothing to do.
430 */
431 if (pri >= cpri)
432 return (0);
433 /*
434 * Always preempt idle.
435 */
436 if (cpri >= PRI_MIN_IDLE)
437 return (1);
438 /*
439 * If preemption is disabled don't preempt others.
440 */
441 if (preempt_thresh == 0)
442 return (0);
443 /*
444 * Preempt if we exceed the threshold.
445 */
446 if (pri <= preempt_thresh)
447 return (1);
448 /*
449 * If we're interactive or better and there is non-interactive
450 * or worse running preempt only remote processors.
451 */
452 if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT)
453 return (1);
454 return (0);
455}
456
457/*
458 * Add a thread to the actual run-queue. Keeps transferable counts up to
459 * date with what is actually on the run-queue. Selects the correct
460 * queue position for timeshare threads.
461 */
462static __inline void
463tdq_runq_add(struct tdq *tdq, struct thread *td, int flags)
464{
465 struct td_sched *ts;
466 u_char pri;
467
468 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
469 THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED);
470
471 pri = td->td_priority;
472 ts = td_get_sched(td);
473 TD_SET_RUNQ(td);
474 if (THREAD_CAN_MIGRATE(td)) {
475 tdq->tdq_transferable++;
476 ts->ts_flags |= TSF_XFERABLE;
477 }
478 if (pri < PRI_MIN_BATCH) {
479 ts->ts_runq = &tdq->tdq_realtime;
480 } else if (pri <= PRI_MAX_BATCH) {
481 ts->ts_runq = &tdq->tdq_timeshare;
482 KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH,
483 ("Invalid priority %d on timeshare runq", pri));
484 /*
485 * This queue contains only priorities between MIN and MAX
486 * realtime. Use the whole queue to represent these values.
487 */
488 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) {
489 pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE;
490 pri = (pri + tdq->tdq_idx) % RQ_NQS;
491 /*
492 * This effectively shortens the queue by one so we
493 * can have a one slot difference between idx and
494 * ridx while we wait for threads to drain.
495 */
496 if (tdq->tdq_ridx != tdq->tdq_idx &&
497 pri == tdq->tdq_ridx)
498 pri = (unsigned char)(pri - 1) % RQ_NQS;
499 } else
500 pri = tdq->tdq_ridx;
501 runq_add_pri(ts->ts_runq, td, pri, flags);
502 return;
503 } else
504 ts->ts_runq = &tdq->tdq_idle;
505 runq_add(ts->ts_runq, td, flags);
506}
507
508/*
509 * Remove a thread from a run-queue. This typically happens when a thread
510 * is selected to run. Running threads are not on the queue and the
511 * transferable count does not reflect them.
512 */
513static __inline void
514tdq_runq_rem(struct tdq *tdq, struct thread *td)
515{
516 struct td_sched *ts;
517
518 ts = td_get_sched(td);
519 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
520 THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED);
521 KASSERT(ts->ts_runq != NULL,
522 ("tdq_runq_remove: thread %p null ts_runq", td));
523 if (ts->ts_flags & TSF_XFERABLE) {
524 tdq->tdq_transferable--;
525 ts->ts_flags &= ~TSF_XFERABLE;
526 }
527 if (ts->ts_runq == &tdq->tdq_timeshare) {
528 if (tdq->tdq_idx != tdq->tdq_ridx)
529 runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx);
530 else
531 runq_remove_idx(ts->ts_runq, td, NULL);
532 } else
533 runq_remove(ts->ts_runq, td);
534}
535
536/*
537 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load
538 * for this thread to the referenced thread queue.
539 */
540static void
541tdq_load_add(struct tdq *tdq, struct thread *td)
542{
543
544 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
545 THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED);
546
547 tdq->tdq_load++;
548 if ((td->td_flags & TDF_NOLOAD) == 0)
549 tdq->tdq_sysload++;
550 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load);
551 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load);
552}
553
554/*
555 * Remove the load from a thread that is transitioning to a sleep state or
556 * exiting.
557 */
558static void
559tdq_load_rem(struct tdq *tdq, struct thread *td)
560{
561
562 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
563 THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED);
564 KASSERT(tdq->tdq_load != 0,
565 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq)));
566
567 tdq->tdq_load--;
568 if ((td->td_flags & TDF_NOLOAD) == 0)
569 tdq->tdq_sysload--;
570 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load);
571 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load);
572}
573
574/*
575 * Bound timeshare latency by decreasing slice size as load increases. We
576 * consider the maximum latency as the sum of the threads waiting to run
577 * aside from curthread and target no more than sched_slice latency but
578 * no less than sched_slice_min runtime.
579 */
580static inline int
581tdq_slice(struct tdq *tdq)
582{
583 int load;
584
585 /*
586 * It is safe to use sys_load here because this is called from
587 * contexts where timeshare threads are running and so there
588 * cannot be higher priority load in the system.
589 */
590 load = tdq->tdq_sysload - 1;
591 if (load >= SCHED_SLICE_MIN_DIVISOR)
592 return (sched_slice_min);
593 if (load <= 1)
594 return (sched_slice);
595 return (sched_slice / load);
596}
597
598/*
599 * Set lowpri to its exact value by searching the run-queue and
600 * evaluating curthread. curthread may be passed as an optimization.
601 */
602static void
603tdq_setlowpri(struct tdq *tdq, struct thread *ctd)
604{
605 struct thread *td;
606
607 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
608 if (ctd == NULL)
609 ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread;
610 td = tdq_choose(tdq);
611 if (td == NULL || td->td_priority > ctd->td_priority)
612 tdq->tdq_lowpri = ctd->td_priority;
613 else
614 tdq->tdq_lowpri = td->td_priority;
615}
616
617#ifdef SMP
618/*
619 * We need some randomness. Implement a classic Linear Congruential
620 * Generator X_{n+1}=(aX_n+c) mod m. These values are optimized for
621 * m = 2^32, a = 69069 and c = 5. We only return the upper 16 bits
622 * of the random state (in the low bits of our answer) to keep
623 * the maximum randomness.
624 */
625static uint32_t
626sched_random(void)
627{
628 uint32_t *rndptr;
629
630 rndptr = DPCPU_PTR(randomval);
631 *rndptr = *rndptr * 69069 + 5;
632
633 return (*rndptr >> 16);
634}
635
636struct cpu_search {
637 cpuset_t *cs_mask; /* The mask of allowed CPUs to choose from. */
638 int cs_prefer; /* Prefer this CPU and groups including it. */
639 int cs_running; /* The thread is now running at cs_prefer. */
640 int cs_pri; /* Min priority for low. */
641 int cs_load; /* Max load for low, min load for high. */
642 int cs_trans; /* Min transferable load for high. */
643};
644
645struct cpu_search_res {
646 int csr_cpu; /* The best CPU found. */
647 int csr_load; /* The load of cs_cpu. */
648};
649
650/*
651 * Search the tree of cpu_groups for the lowest or highest loaded CPU.
652 * These routines actually compare the load on all paths through the tree
653 * and find the least loaded cpu on the least loaded path, which may differ
654 * from the least loaded cpu in the system. This balances work among caches
655 * and buses.
656 */
657static int
658cpu_search_lowest(const struct cpu_group *cg, const struct cpu_search *s,
659 struct cpu_search_res *r)
660{
661 struct cpu_search_res lr;
662 struct tdq *tdq;
663 int c, bload, l, load, p, total;
664
665 total = 0;
666 bload = INT_MAX;
667 r->csr_cpu = -1;
668
669 /* Loop through children CPU groups if there are any. */
670 if (cg->cg_children > 0) {
671 for (c = cg->cg_children - 1; c >= 0; c--) {
672 load = cpu_search_lowest(&cg->cg_child[c], s, &lr);
673 total += load;
674
675 /*
676 * When balancing do not prefer SMT groups with load >1.
677 * It allows round-robin between SMT groups with equal
678 * load within parent group for more fair scheduling.
679 */
680 if (__predict_false(s->cs_running) &&
681 (cg->cg_child[c].cg_flags & CG_FLAG_THREAD) &&
682 load >= 128 && (load & 128) != 0)
683 load += 128;
684
685 if (lr.csr_cpu >= 0 && (load < bload ||
686 (load == bload && lr.csr_load < r->csr_load))) {
687 bload = load;
688 r->csr_cpu = lr.csr_cpu;
689 r->csr_load = lr.csr_load;
690 }
691 }
692 return (total);
693 }
694
695 /* Loop through children CPUs otherwise. */
696 for (c = cg->cg_last; c >= cg->cg_first; c--) {
697 if (!CPU_ISSET(c, &cg->cg_mask))
698 continue;
699 tdq = TDQ_CPU(c);
700 l = tdq->tdq_load;
701 if (c == s->cs_prefer) {
702 if (__predict_false(s->cs_running))
703 l--;
704 p = 128;
705 } else
706 p = 0;
707 load = l * 256;
708 total += load - p;
709
710 /*
711 * Check this CPU is acceptable.
712 * If the threads is already on the CPU, don't look on the TDQ
713 * priority, since it can be the priority of the thread itself.
714 */
715 if (l > s->cs_load || (tdq->tdq_lowpri <= s->cs_pri &&
716 (!s->cs_running || c != s->cs_prefer)) ||
717 !CPU_ISSET(c, s->cs_mask))
718 continue;
719
720 /*
721 * When balancing do not prefer CPUs with load > 1.
722 * It allows round-robin between CPUs with equal load
723 * within the CPU group for more fair scheduling.
724 */
725 if (__predict_false(s->cs_running) && l > 0)
726 p = 0;
727
728 load -= sched_random() % 128;
729 if (bload > load - p) {
730 bload = load - p;
731 r->csr_cpu = c;
732 r->csr_load = load;
733 }
734 }
735 return (total);
736}
737
738static int
739cpu_search_highest(const struct cpu_group *cg, const struct cpu_search *s,
740 struct cpu_search_res *r)
741{
742 struct cpu_search_res lr;
743 struct tdq *tdq;
744 int c, bload, l, load, total;
745
746 total = 0;
747 bload = INT_MIN;
748 r->csr_cpu = -1;
749
750 /* Loop through children CPU groups if there are any. */
751 if (cg->cg_children > 0) {
752 for (c = cg->cg_children - 1; c >= 0; c--) {
753 load = cpu_search_highest(&cg->cg_child[c], s, &lr);
754 total += load;
755 if (lr.csr_cpu >= 0 && (load > bload ||
756 (load == bload && lr.csr_load > r->csr_load))) {
757 bload = load;
758 r->csr_cpu = lr.csr_cpu;
759 r->csr_load = lr.csr_load;
760 }
761 }
762 return (total);
763 }
764
765 /* Loop through children CPUs otherwise. */
766 for (c = cg->cg_last; c >= cg->cg_first; c--) {
767 if (!CPU_ISSET(c, &cg->cg_mask))
768 continue;
769 tdq = TDQ_CPU(c);
770 l = tdq->tdq_load;
771 load = l * 256;
772 total += load;
773
774 /*
775 * Check this CPU is acceptable.
776 */
777 if (l < s->cs_load || (tdq->tdq_transferable < s->cs_trans) ||
778 !CPU_ISSET(c, s->cs_mask))
779 continue;
780
781 load -= sched_random() % 256;
782 if (load > bload) {
783 bload = load;
784 r->csr_cpu = c;
785 }
786 }
787 r->csr_load = bload;
788 return (total);
789}
790
791/*
792 * Find the cpu with the least load via the least loaded path that has a
793 * lowpri greater than pri pri. A pri of -1 indicates any priority is
794 * acceptable.
795 */
796static inline int
797sched_lowest(const struct cpu_group *cg, cpuset_t *mask, int pri, int maxload,
798 int prefer, int running)
799{
800 struct cpu_search s;
801 struct cpu_search_res r;
802
803 s.cs_prefer = prefer;
804 s.cs_running = running;
805 s.cs_mask = mask;
806 s.cs_pri = pri;
807 s.cs_load = maxload;
808 cpu_search_lowest(cg, &s, &r);
809 return (r.csr_cpu);
810}
811
812/*
813 * Find the cpu with the highest load via the highest loaded path.
814 */
815static inline int
816sched_highest(const struct cpu_group *cg, cpuset_t *mask, int minload,
817 int mintrans)
818{
819 struct cpu_search s;
820 struct cpu_search_res r;
821
822 s.cs_mask = mask;
823 s.cs_load = minload;
824 s.cs_trans = mintrans;
825 cpu_search_highest(cg, &s, &r);
826 return (r.csr_cpu);
827}
828
829static void
830sched_balance_group(struct cpu_group *cg)
831{
832 struct tdq *tdq;
833 struct thread *td;
834 cpuset_t hmask, lmask;
835 int high, low, anylow;
836
837 CPU_FILL(&hmask);
838 for (;;) {
839 high = sched_highest(cg, &hmask, 1, 0);
840 /* Stop if there is no more CPU with transferrable threads. */
841 if (high == -1)
842 break;
843 CPU_CLR(high, &hmask);
844 CPU_COPY(&hmask, &lmask);
845 /* Stop if there is no more CPU left for low. */
846 if (CPU_EMPTY(&lmask))
847 break;
848 tdq = TDQ_CPU(high);
849 if (tdq->tdq_load == 1) {
850 /*
851 * There is only one running thread. We can't move
852 * it from here, so tell it to pick new CPU by itself.
853 */
854 TDQ_LOCK(tdq);
855 td = pcpu_find(high)->pc_curthread;
856 if ((td->td_flags & TDF_IDLETD) == 0 &&
857 THREAD_CAN_MIGRATE(td)) {
858 td->td_flags |= TDF_NEEDRESCHED | TDF_PICKCPU;
859 if (high != curcpu)
860 ipi_cpu(high, IPI_AST);
861 }
862 TDQ_UNLOCK(tdq);
863 break;
864 }
865 anylow = 1;
866nextlow:
867 if (tdq->tdq_transferable == 0)
868 continue;
869 low = sched_lowest(cg, &lmask, -1, tdq->tdq_load - 1, high, 1);
870 /* Stop if we looked well and found no less loaded CPU. */
871 if (anylow && low == -1)
872 break;
873 /* Go to next high if we found no less loaded CPU. */
874 if (low == -1)
875 continue;
876 /* Transfer thread from high to low. */
877 if (sched_balance_pair(tdq, TDQ_CPU(low))) {
878 /* CPU that got thread can no longer be a donor. */
879 CPU_CLR(low, &hmask);
880 } else {
881 /*
882 * If failed, then there is no threads on high
883 * that can run on this low. Drop low from low
884 * mask and look for different one.
885 */
886 CPU_CLR(low, &lmask);
887 anylow = 0;
888 goto nextlow;
889 }
890 }
891}
892
893static void
894sched_balance(void)
895{
896 struct tdq *tdq;
897
898 balance_ticks = max(balance_interval / 2, 1) +
899 (sched_random() % balance_interval);
900 tdq = TDQ_SELF();
901 TDQ_UNLOCK(tdq);
902 sched_balance_group(cpu_top);
903 TDQ_LOCK(tdq);
904}
905
906/*
907 * Lock two thread queues using their address to maintain lock order.
908 */
909static void
910tdq_lock_pair(struct tdq *one, struct tdq *two)
911{
912 if (one < two) {
913 TDQ_LOCK(one);
914 TDQ_LOCK_FLAGS(two, MTX_DUPOK);
915 } else {
916 TDQ_LOCK(two);
917 TDQ_LOCK_FLAGS(one, MTX_DUPOK);
918 }
919}
920
921/*
922 * Unlock two thread queues. Order is not important here.
923 */
924static void
925tdq_unlock_pair(struct tdq *one, struct tdq *two)
926{
927 TDQ_UNLOCK(one);
928 TDQ_UNLOCK(two);
929}
930
931/*
932 * Transfer load between two imbalanced thread queues.
933 */
934static int
935sched_balance_pair(struct tdq *high, struct tdq *low)
936{
937 struct thread *td;
938 int cpu;
939
940 tdq_lock_pair(high, low);
941 td = NULL;
942 /*
943 * Transfer a thread from high to low.
944 */
945 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load &&
946 (td = tdq_move(high, low)) != NULL) {
947 /*
948 * In case the target isn't the current cpu notify it of the
949 * new load, possibly sending an IPI to force it to reschedule.
950 */
951 cpu = TDQ_ID(low);
952 if (cpu != PCPU_GET(cpuid))
953 tdq_notify(low, td);
954 }
955 tdq_unlock_pair(high, low);
956 return (td != NULL);
957}
958
959/*
960 * Move a thread from one thread queue to another.
961 */
962static struct thread *
963tdq_move(struct tdq *from, struct tdq *to)
964{
965 struct thread *td;
966 struct tdq *tdq;
967 int cpu;
968
969 TDQ_LOCK_ASSERT(from, MA_OWNED);
970 TDQ_LOCK_ASSERT(to, MA_OWNED);
971
972 tdq = from;
973 cpu = TDQ_ID(to);
974 td = tdq_steal(tdq, cpu);
975 if (td == NULL)
976 return (NULL);
977
978 /*
979 * Although the run queue is locked the thread may be
980 * blocked. We can not set the lock until it is unblocked.
981 */
982 thread_lock_block_wait(td);
983 sched_rem(td);
984 THREAD_LOCKPTR_ASSERT(td, TDQ_LOCKPTR(from));
985 td->td_lock = TDQ_LOCKPTR(to);
986 td_get_sched(td)->ts_cpu = cpu;
987 tdq_add(to, td, SRQ_YIELDING);
988
989 return (td);
990}
991
992/*
993 * This tdq has idled. Try to steal a thread from another cpu and switch
994 * to it.
995 */
996static int
997tdq_idled(struct tdq *tdq)
998{
999 struct cpu_group *cg, *parent;
1000 struct tdq *steal;
1001 cpuset_t mask;
1002 int cpu, switchcnt, goup;
1003
1004 if (smp_started == 0 || steal_idle == 0 || tdq->tdq_cg == NULL)
1005 return (1);
1006 CPU_FILL(&mask);
1007 CPU_CLR(PCPU_GET(cpuid), &mask);
1008 restart:
1009 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
1010 for (cg = tdq->tdq_cg, goup = 0; ; ) {
1011 cpu = sched_highest(cg, &mask, steal_thresh, 1);
1012 /*
1013 * We were assigned a thread but not preempted. Returning
1014 * 0 here will cause our caller to switch to it.
1015 */
1016 if (tdq->tdq_load)
1017 return (0);
1018
1019 /*
1020 * We found no CPU to steal from in this group. Escalate to
1021 * the parent and repeat. But if parent has only two children
1022 * groups we can avoid searching this group again by searching
1023 * the other one specifically and then escalating two levels.
1024 */
1025 if (cpu == -1) {
1026 if (goup) {
1027 cg = cg->cg_parent;
1028 goup = 0;
1029 }
1030 parent = cg->cg_parent;
1031 if (parent == NULL)
1032 return (1);
1033 if (parent->cg_children == 2) {
1034 if (cg == &parent->cg_child[0])
1035 cg = &parent->cg_child[1];
1036 else
1037 cg = &parent->cg_child[0];
1038 goup = 1;
1039 } else
1040 cg = parent;
1041 continue;
1042 }
1043 steal = TDQ_CPU(cpu);
1044 /*
1045 * The data returned by sched_highest() is stale and
1046 * the chosen CPU no longer has an eligible thread.
1047 *
1048 * Testing this ahead of tdq_lock_pair() only catches
1049 * this situation about 20% of the time on an 8 core
1050 * 16 thread Ryzen 7, but it still helps performance.
1051 */
1052 if (steal->tdq_load < steal_thresh ||
1053 steal->tdq_transferable == 0)
1054 goto restart;
1055 /*
1056 * Try to lock both queues. If we are assigned a thread while
1057 * waited for the lock, switch to it now instead of stealing.
1058 * If we can't get the lock, then somebody likely got there
1059 * first so continue searching.
1060 */
1061 TDQ_LOCK(tdq);
1062 if (tdq->tdq_load > 0) {
1063 mi_switch(SW_VOL | SWT_IDLE);
1064 return (0);
1065 }
1066 if (TDQ_TRYLOCK_FLAGS(steal, MTX_DUPOK) == 0) {
1067 TDQ_UNLOCK(tdq);
1068 CPU_CLR(cpu, &mask);
1069 continue;
1070 }
1071 /*
1072 * The data returned by sched_highest() is stale and
1073 * the chosen CPU no longer has an eligible thread, or
1074 * we were preempted and the CPU loading info may be out
1075 * of date. The latter is rare. In either case restart
1076 * the search.
1077 */
1078 if (steal->tdq_load < steal_thresh ||
1079 steal->tdq_transferable == 0 ||
1080 switchcnt != tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt) {
1081 tdq_unlock_pair(tdq, steal);
1082 goto restart;
1083 }
1084 /*
1085 * Steal the thread and switch to it.
1086 */
1087 if (tdq_move(steal, tdq) != NULL)
1088 break;
1089 /*
1090 * We failed to acquire a thread even though it looked
1091 * like one was available. This could be due to affinity
1092 * restrictions or for other reasons. Loop again after
1093 * removing this CPU from the set. The restart logic
1094 * above does not restore this CPU to the set due to the
1095 * likelyhood of failing here again.
1096 */
1097 CPU_CLR(cpu, &mask);
1098 tdq_unlock_pair(tdq, steal);
1099 }
1100 TDQ_UNLOCK(steal);
1101 mi_switch(SW_VOL | SWT_IDLE);
1102 return (0);
1103}
1104
1105/*
1106 * Notify a remote cpu of new work. Sends an IPI if criteria are met.
1107 */
1108static void
1109tdq_notify(struct tdq *tdq, struct thread *td)
1110{
1111 struct thread *ctd;
1112 int pri;
1113 int cpu;
1114
1115 if (tdq->tdq_owepreempt)
1116 return;
1117 cpu = td_get_sched(td)->ts_cpu;
1118 pri = td->td_priority;
1119 ctd = pcpu_find(cpu)->pc_curthread;
1120 if (!sched_shouldpreempt(pri, ctd->td_priority, 1))
1121 return;
1122
1123 /*
1124 * Make sure that our caller's earlier update to tdq_load is
1125 * globally visible before we read tdq_cpu_idle. Idle thread
1126 * accesses both of them without locks, and the order is important.
1127 */
1128 atomic_thread_fence_seq_cst();
1129
1130 if (TD_IS_IDLETHREAD(ctd)) {
1131 /*
1132 * If the MD code has an idle wakeup routine try that before
1133 * falling back to IPI.
1134 */
1135 if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu))
1136 return;
1137 }
1138
1139 /*
1140 * The run queues have been updated, so any switch on the remote CPU
1141 * will satisfy the preemption request.
1142 */
1143 tdq->tdq_owepreempt = 1;
1144 ipi_cpu(cpu, IPI_PREEMPT);
1145}
1146
1147/*
1148 * Steals load from a timeshare queue. Honors the rotating queue head
1149 * index.
1150 */
1151static struct thread *
1152runq_steal_from(struct runq *rq, int cpu, u_char start)
1153{
1154 struct rqbits *rqb;
1155 struct rqhead *rqh;
1156 struct thread *td, *first;
1157 int bit;
1158 int i;
1159
1160 rqb = &rq->rq_status;
1161 bit = start & (RQB_BPW -1);
1162 first = NULL;
1163again:
1164 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) {
1165 if (rqb->rqb_bits[i] == 0)
1166 continue;
1167 if (bit == 0)
1168 bit = RQB_FFS(rqb->rqb_bits[i]);
1169 for (; bit < RQB_BPW; bit++) {
1170 if ((rqb->rqb_bits[i] & (1ul << bit)) == 0)
1171 continue;
1172 rqh = &rq->rq_queues[bit + (i << RQB_L2BPW)];
1173 TAILQ_FOREACH(td, rqh, td_runq) {
1174 if (first) {
1175 if (THREAD_CAN_MIGRATE(td) &&
1176 THREAD_CAN_SCHED(td, cpu))
1177 return (td);
1178 } else
1179 first = td;
1180 }
1181 }
1182 }
1183 if (start != 0) {
1184 start = 0;
1185 goto again;
1186 }
1187
1188 if (first && THREAD_CAN_MIGRATE(first) &&
1189 THREAD_CAN_SCHED(first, cpu))
1190 return (first);
1191 return (NULL);
1192}
1193
1194/*
1195 * Steals load from a standard linear queue.
1196 */
1197static struct thread *
1198runq_steal(struct runq *rq, int cpu)
1199{
1200 struct rqhead *rqh;
1201 struct rqbits *rqb;
1202 struct thread *td;
1203 int word;
1204 int bit;
1205
1206 rqb = &rq->rq_status;
1207 for (word = 0; word < RQB_LEN; word++) {
1208 if (rqb->rqb_bits[word] == 0)
1209 continue;
1210 for (bit = 0; bit < RQB_BPW; bit++) {
1211 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0)
1212 continue;
1213 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)];
1214 TAILQ_FOREACH(td, rqh, td_runq)
1215 if (THREAD_CAN_MIGRATE(td) &&
1216 THREAD_CAN_SCHED(td, cpu))
1217 return (td);
1218 }
1219 }
1220 return (NULL);
1221}
1222
1223/*
1224 * Attempt to steal a thread in priority order from a thread queue.
1225 */
1226static struct thread *
1227tdq_steal(struct tdq *tdq, int cpu)
1228{
1229 struct thread *td;
1230
1231 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
1232 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL)
1233 return (td);
1234 if ((td = runq_steal_from(&tdq->tdq_timeshare,
1235 cpu, tdq->tdq_ridx)) != NULL)
1236 return (td);
1237 return (runq_steal(&tdq->tdq_idle, cpu));
1238}
1239
1240/*
1241 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the
1242 * current lock and returns with the assigned queue locked.
1243 */
1244static inline struct tdq *
1245sched_setcpu(struct thread *td, int cpu, int flags)
1246{
1247
1248 struct tdq *tdq;
1249 struct mtx *mtx;
1250
1251 THREAD_LOCK_ASSERT(td, MA_OWNED);
1252 tdq = TDQ_CPU(cpu);
1253 td_get_sched(td)->ts_cpu = cpu;
1254 /*
1255 * If the lock matches just return the queue.
1256 */
1257 if (td->td_lock == TDQ_LOCKPTR(tdq)) {
1258 KASSERT((flags & SRQ_HOLD) == 0,
1259 ("sched_setcpu: Invalid lock for SRQ_HOLD"));
1260 return (tdq);
1261 }
1262
1263 /*
1264 * The hard case, migration, we need to block the thread first to
1265 * prevent order reversals with other cpus locks.
1266 */
1267 spinlock_enter();
1268 mtx = thread_lock_block(td);
1269 if ((flags & SRQ_HOLD) == 0)
1270 mtx_unlock_spin(mtx);
1271 TDQ_LOCK(tdq);
1272 thread_lock_unblock(td, TDQ_LOCKPTR(tdq));
1273 spinlock_exit();
1274 return (tdq);
1275}
1276
1277SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding");
1278SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity");
1279SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity");
1280SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load");
1281SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu");
1282SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration");
1283
1284static int
1285sched_pickcpu(struct thread *td, int flags)
1286{
1287 struct cpu_group *cg, *ccg;
1288 struct td_sched *ts;
1289 struct tdq *tdq;
1290 cpuset_t *mask;
1291 int cpu, pri, r, self, intr;
1292
1293 self = PCPU_GET(cpuid);
1294 ts = td_get_sched(td);
1295 KASSERT(!CPU_ABSENT(ts->ts_cpu), ("sched_pickcpu: Start scheduler on "
1296 "absent CPU %d for thread %s.", ts->ts_cpu, td->td_name));
1297 if (smp_started == 0)
1298 return (self);
1299 /*
1300 * Don't migrate a running thread from sched_switch().
1301 */
1302 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td))
1303 return (ts->ts_cpu);
1304 /*
1305 * Prefer to run interrupt threads on the processors that generate
1306 * the interrupt.
1307 */
1308 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) &&
1309 curthread->td_intr_nesting_level) {
1310 tdq = TDQ_SELF();
1311 if (tdq->tdq_lowpri >= PRI_MIN_IDLE) {
1312 SCHED_STAT_INC(pickcpu_idle_affinity);
1313 return (self);
1314 }
1315 ts->ts_cpu = self;
1316 intr = 1;
1317 cg = tdq->tdq_cg;
1318 goto llc;
1319 } else {
1320 intr = 0;
1321 tdq = TDQ_CPU(ts->ts_cpu);
1322 cg = tdq->tdq_cg;
1323 }
1324 /*
1325 * If the thread can run on the last cpu and the affinity has not
1326 * expired and it is idle, run it there.
1327 */
1328 if (THREAD_CAN_SCHED(td, ts->ts_cpu) &&
1329 tdq->tdq_lowpri >= PRI_MIN_IDLE &&
1330 SCHED_AFFINITY(ts, CG_SHARE_L2)) {
1331 if (cg->cg_flags & CG_FLAG_THREAD) {
1332 /* Check all SMT threads for being idle. */
1333 for (cpu = cg->cg_first; cpu <= cg->cg_last; cpu++) {
1334 if (CPU_ISSET(cpu, &cg->cg_mask) &&
1335 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE)
1336 break;
1337 }
1338 if (cpu > cg->cg_last) {
1339 SCHED_STAT_INC(pickcpu_idle_affinity);
1340 return (ts->ts_cpu);
1341 }
1342 } else {
1343 SCHED_STAT_INC(pickcpu_idle_affinity);
1344 return (ts->ts_cpu);
1345 }
1346 }
1347llc:
1348 /*
1349 * Search for the last level cache CPU group in the tree.
1350 * Skip SMT, identical groups and caches with expired affinity.
1351 * Interrupt threads affinity is explicit and never expires.
1352 */
1353 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) {
1354 if (cg->cg_flags & CG_FLAG_THREAD)
1355 continue;
1356 if (cg->cg_children == 1 || cg->cg_count == 1)
1357 continue;
1358 if (cg->cg_level == CG_SHARE_NONE ||
1359 (!intr && !SCHED_AFFINITY(ts, cg->cg_level)))
1360 continue;
1361 ccg = cg;
1362 }
1363 /* Found LLC shared by all CPUs, so do a global search. */
1364 if (ccg == cpu_top)
1365 ccg = NULL;
1366 cpu = -1;
1367 mask = &td->td_cpuset->cs_mask;
1368 pri = td->td_priority;
1369 r = TD_IS_RUNNING(td);
1370 /*
1371 * Try hard to keep interrupts within found LLC. Search the LLC for
1372 * the least loaded CPU we can run now. For NUMA systems it should
1373 * be within target domain, and it also reduces scheduling overhead.
1374 */
1375 if (ccg != NULL && intr) {
1376 cpu = sched_lowest(ccg, mask, pri, INT_MAX, ts->ts_cpu, r);
1377 if (cpu >= 0)
1378 SCHED_STAT_INC(pickcpu_intrbind);
1379 } else
1380 /* Search the LLC for the least loaded idle CPU we can run now. */
1381 if (ccg != NULL) {
1382 cpu = sched_lowest(ccg, mask, max(pri, PRI_MAX_TIMESHARE),
1383 INT_MAX, ts->ts_cpu, r);
1384 if (cpu >= 0)
1385 SCHED_STAT_INC(pickcpu_affinity);
1386 }
1387 /* Search globally for the least loaded CPU we can run now. */
1388 if (cpu < 0) {
1389 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu, r);
1390 if (cpu >= 0)
1391 SCHED_STAT_INC(pickcpu_lowest);
1392 }
1393 /* Search globally for the least loaded CPU. */
1394 if (cpu < 0) {
1395 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu, r);
1396 if (cpu >= 0)
1397 SCHED_STAT_INC(pickcpu_lowest);
1398 }
1399 KASSERT(cpu >= 0, ("sched_pickcpu: Failed to find a cpu."));
1400 KASSERT(!CPU_ABSENT(cpu), ("sched_pickcpu: Picked absent CPU %d.", cpu));
1401 /*
1402 * Compare the lowest loaded cpu to current cpu.
1403 */
1404 tdq = TDQ_CPU(cpu);
1405 if (THREAD_CAN_SCHED(td, self) && TDQ_SELF()->tdq_lowpri > pri &&
1406 tdq->tdq_lowpri < PRI_MIN_IDLE &&
1407 TDQ_SELF()->tdq_load <= tdq->tdq_load + 1) {
1408 SCHED_STAT_INC(pickcpu_local);
1409 cpu = self;
1410 }
1411 if (cpu != ts->ts_cpu)
1412 SCHED_STAT_INC(pickcpu_migration);
1413 return (cpu);
1414}
1415#endif
1416
1417/*
1418 * Pick the highest priority task we have and return it.
1419 */
1420static struct thread *
1421tdq_choose(struct tdq *tdq)
1422{
1423 struct thread *td;
1424
1425 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
1426 td = runq_choose(&tdq->tdq_realtime);
1427 if (td != NULL)
1428 return (td);
1429 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx);
1430 if (td != NULL) {
1431 KASSERT(td->td_priority >= PRI_MIN_BATCH,
1432 ("tdq_choose: Invalid priority on timeshare queue %d",
1433 td->td_priority));
1434 return (td);
1435 }
1436 td = runq_choose(&tdq->tdq_idle);
1437 if (td != NULL) {
1438 KASSERT(td->td_priority >= PRI_MIN_IDLE,
1439 ("tdq_choose: Invalid priority on idle queue %d",
1440 td->td_priority));
1441 return (td);
1442 }
1443
1444 return (NULL);
1445}
1446
1447/*
1448 * Initialize a thread queue.
1449 */
1450static void
1451tdq_setup(struct tdq *tdq, int id)
1452{
1453
1454 if (bootverbose)
1455 printf("ULE: setup cpu %d\n", id);
1456 runq_init(&tdq->tdq_realtime);
1457 runq_init(&tdq->tdq_timeshare);
1458 runq_init(&tdq->tdq_idle);
1459 tdq->tdq_id = id;
1460 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name),
1461 "sched lock %d", (int)TDQ_ID(tdq));
1462 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", MTX_SPIN);
1463#ifdef KTR
1464 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname),
1465 "CPU %d load", (int)TDQ_ID(tdq));
1466#endif
1467}
1468
1469#ifdef SMP
1470static void
1471sched_setup_smp(void)
1472{
1473 struct tdq *tdq;
1474 int i;
1475
1476 cpu_top = smp_topo();
1477 CPU_FOREACH(i) {
1478 tdq = DPCPU_ID_PTR(i, tdq);
1479 tdq_setup(tdq, i);
1480 tdq->tdq_cg = smp_topo_find(cpu_top, i);
1481 if (tdq->tdq_cg == NULL)
1482 panic("Can't find cpu group for %d\n", i);
1483 DPCPU_ID_SET(i, randomval, i * 69069 + 5);
1484 }
1485 PCPU_SET(sched, DPCPU_PTR(tdq));
1486 balance_tdq = TDQ_SELF();
1487}
1488#endif
1489
1490/*
1491 * Setup the thread queues and initialize the topology based on MD
1492 * information.
1493 */
1494static void
1495sched_setup(void *dummy)
1496{
1497 struct tdq *tdq;
1498
1499#ifdef SMP
1500 sched_setup_smp();
1501#else
1502 tdq_setup(TDQ_SELF(), 0);
1503#endif
1504 tdq = TDQ_SELF();
1505
1506 /* Add thread0's load since it's running. */
1507 TDQ_LOCK(tdq);
1508 thread0.td_lock = TDQ_LOCKPTR(tdq);
1509 tdq_load_add(tdq, &thread0);
1510 tdq->tdq_lowpri = thread0.td_priority;
1511 TDQ_UNLOCK(tdq);
1512}
1513
1514/*
1515 * This routine determines time constants after stathz and hz are setup.
1516 */
1517/* ARGSUSED */
1518static void
1519sched_initticks(void *dummy)
1520{
1521 int incr;
1522
1523 realstathz = stathz ? stathz : hz;
1524 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR;
1525 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR;
1526 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
1527 realstathz);
1528
1529 /*
1530 * tickincr is shifted out by 10 to avoid rounding errors due to
1531 * hz not being evenly divisible by stathz on all platforms.
1532 */
1533 incr = (hz << SCHED_TICK_SHIFT) / realstathz;
1534 /*
1535 * This does not work for values of stathz that are more than
1536 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen.
1537 */
1538 if (incr == 0)
1539 incr = 1;
1540 tickincr = incr;
1541#ifdef SMP
1542 /*
1543 * Set the default balance interval now that we know
1544 * what realstathz is.
1545 */
1546 balance_interval = realstathz;
1547 balance_ticks = balance_interval;
1548 affinity = SCHED_AFFINITY_DEFAULT;
1549#endif
1550 if (sched_idlespinthresh < 0)
1551 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz;
1552}
1553
1554/*
1555 * This is the core of the interactivity algorithm. Determines a score based
1556 * on past behavior. It is the ratio of sleep time to run time scaled to
1557 * a [0, 100] integer. This is the voluntary sleep time of a process, which
1558 * differs from the cpu usage because it does not account for time spent
1559 * waiting on a run-queue. Would be prettier if we had floating point.
1560 *
1561 * When a thread's sleep time is greater than its run time the
1562 * calculation is:
1563 *
1564 * scaling factor
1565 * interactivity score = ---------------------
1566 * sleep time / run time
1567 *
1568 *
1569 * When a thread's run time is greater than its sleep time the
1570 * calculation is:
1571 *
1572 * scaling factor
1573 * interactivity score = 2 * scaling factor - ---------------------
1574 * run time / sleep time
1575 */
1576static int
1577sched_interact_score(struct thread *td)
1578{
1579 struct td_sched *ts;
1580 int div;
1581
1582 ts = td_get_sched(td);
1583 /*
1584 * The score is only needed if this is likely to be an interactive
1585 * task. Don't go through the expense of computing it if there's
1586 * no chance.
1587 */
1588 if (sched_interact <= SCHED_INTERACT_HALF &&
1589 ts->ts_runtime >= ts->ts_slptime)
1590 return (SCHED_INTERACT_HALF);
1591
1592 if (ts->ts_runtime > ts->ts_slptime) {
1593 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF);
1594 return (SCHED_INTERACT_HALF +
1595 (SCHED_INTERACT_HALF - (ts->ts_slptime / div)));
1596 }
1597 if (ts->ts_slptime > ts->ts_runtime) {
1598 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF);
1599 return (ts->ts_runtime / div);
1600 }
1601 /* runtime == slptime */
1602 if (ts->ts_runtime)
1603 return (SCHED_INTERACT_HALF);
1604
1605 /*
1606 * This can happen if slptime and runtime are 0.
1607 */
1608 return (0);
1609
1610}
1611
1612/*
1613 * Scale the scheduling priority according to the "interactivity" of this
1614 * process.
1615 */
1616static void
1617sched_priority(struct thread *td)
1618{
1619 u_int pri, score;
1620
1621 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE)
1622 return;
1623 /*
1624 * If the score is interactive we place the thread in the realtime
1625 * queue with a priority that is less than kernel and interrupt
1626 * priorities. These threads are not subject to nice restrictions.
1627 *
1628 * Scores greater than this are placed on the normal timeshare queue
1629 * where the priority is partially decided by the most recent cpu
1630 * utilization and the rest is decided by nice value.
1631 *
1632 * The nice value of the process has a linear effect on the calculated
1633 * score. Negative nice values make it easier for a thread to be
1634 * considered interactive.
1635 */
1636 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice);
1637 if (score < sched_interact) {
1638 pri = PRI_MIN_INTERACT;
1639 pri += (PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) * score /
1640 sched_interact;
1641 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT,
1642 ("sched_priority: invalid interactive priority %u score %u",
1643 pri, score));
1644 } else {
1645 pri = SCHED_PRI_MIN;
1646 if (td_get_sched(td)->ts_ticks)
1647 pri += min(SCHED_PRI_TICKS(td_get_sched(td)),
1648 SCHED_PRI_RANGE - 1);
1649 pri += SCHED_PRI_NICE(td->td_proc->p_nice);
1650 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH,
1651 ("sched_priority: invalid priority %u: nice %d, "
1652 "ticks %d ftick %d ltick %d tick pri %d",
1653 pri, td->td_proc->p_nice, td_get_sched(td)->ts_ticks,
1654 td_get_sched(td)->ts_ftick, td_get_sched(td)->ts_ltick,
1655 SCHED_PRI_TICKS(td_get_sched(td))));
1656 }
1657 sched_user_prio(td, pri);
1658
1659 return;
1660}
1661
1662/*
1663 * This routine enforces a maximum limit on the amount of scheduling history
1664 * kept. It is called after either the slptime or runtime is adjusted. This
1665 * function is ugly due to integer math.
1666 */
1667static void
1668sched_interact_update(struct thread *td)
1669{
1670 struct td_sched *ts;
1671 u_int sum;
1672
1673 ts = td_get_sched(td);
1674 sum = ts->ts_runtime + ts->ts_slptime;
1675 if (sum < SCHED_SLP_RUN_MAX)
1676 return;
1677 /*
1678 * This only happens from two places:
1679 * 1) We have added an unusual amount of run time from fork_exit.
1680 * 2) We have added an unusual amount of sleep time from sched_sleep().
1681 */
1682 if (sum > SCHED_SLP_RUN_MAX * 2) {
1683 if (ts->ts_runtime > ts->ts_slptime) {
1684 ts->ts_runtime = SCHED_SLP_RUN_MAX;
1685 ts->ts_slptime = 1;
1686 } else {
1687 ts->ts_slptime = SCHED_SLP_RUN_MAX;
1688 ts->ts_runtime = 1;
1689 }
1690 return;
1691 }
1692 /*
1693 * If we have exceeded by more than 1/5th then the algorithm below
1694 * will not bring us back into range. Dividing by two here forces
1695 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX]
1696 */
1697 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) {
1698 ts->ts_runtime /= 2;
1699 ts->ts_slptime /= 2;
1700 return;
1701 }
1702 ts->ts_runtime = (ts->ts_runtime / 5) * 4;
1703 ts->ts_slptime = (ts->ts_slptime / 5) * 4;
1704}
1705
1706/*
1707 * Scale back the interactivity history when a child thread is created. The
1708 * history is inherited from the parent but the thread may behave totally
1709 * differently. For example, a shell spawning a compiler process. We want
1710 * to learn that the compiler is behaving badly very quickly.
1711 */
1712static void
1713sched_interact_fork(struct thread *td)
1714{
1715 struct td_sched *ts;
1716 int ratio;
1717 int sum;
1718
1719 ts = td_get_sched(td);
1720 sum = ts->ts_runtime + ts->ts_slptime;
1721 if (sum > SCHED_SLP_RUN_FORK) {
1722 ratio = sum / SCHED_SLP_RUN_FORK;
1723 ts->ts_runtime /= ratio;
1724 ts->ts_slptime /= ratio;
1725 }
1726}
1727
1728/*
1729 * Called from proc0_init() to setup the scheduler fields.
1730 */
1731void
1732schedinit(void)
1733{
1734 struct td_sched *ts0;
1735
1736 /*
1737 * Set up the scheduler specific parts of thread0.
1738 */
1739 ts0 = td_get_sched(&thread0);
1740 ts0->ts_ltick = ticks;
1741 ts0->ts_ftick = ticks;
1742 ts0->ts_slice = 0;
1743 ts0->ts_cpu = curcpu; /* set valid CPU number */
1744}
1745
1746/*
1747 * schedinit_ap() is needed prior to calling sched_throw(NULL) to ensure that
1748 * the pcpu requirements are met for any calls in the period between curthread
1749 * initialization and sched_throw(). One can safely add threads to the queue
1750 * before sched_throw(), for instance, as long as the thread lock is setup
1751 * correctly.
1752 *
1753 * TDQ_SELF() relies on the below sched pcpu setting; it may be used only
1754 * after schedinit_ap().
1755 */
1756void
1757schedinit_ap(void)
1758{
1759
1760#ifdef SMP
1761 PCPU_SET(sched, DPCPU_PTR(tdq));
1762#endif
1763 PCPU_GET(idlethread)->td_lock = TDQ_LOCKPTR(TDQ_SELF());
1764}
1765
1766/*
1767 * This is only somewhat accurate since given many processes of the same
1768 * priority they will switch when their slices run out, which will be
1769 * at most sched_slice stathz ticks.
1770 */
1771int
1772sched_rr_interval(void)
1773{
1774
1775 /* Convert sched_slice from stathz to hz. */
1776 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz));
1777}
1778
1779/*
1780 * Update the percent cpu tracking information when it is requested or
1781 * the total history exceeds the maximum. We keep a sliding history of
1782 * tick counts that slowly decays. This is less precise than the 4BSD
1783 * mechanism since it happens with less regular and frequent events.
1784 */
1785static void
1786sched_pctcpu_update(struct td_sched *ts, int run)
1787{
1788 int t = ticks;
1789
1790 /*
1791 * The signed difference may be negative if the thread hasn't run for
1792 * over half of the ticks rollover period.
1793 */
1794 if ((u_int)(t - ts->ts_ltick) >= SCHED_TICK_TARG) {
1795 ts->ts_ticks = 0;
1796 ts->ts_ftick = t - SCHED_TICK_TARG;
1797 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) {
1798 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) *
1799 (ts->ts_ltick - (t - SCHED_TICK_TARG));
1800 ts->ts_ftick = t - SCHED_TICK_TARG;
1801 }
1802 if (run)
1803 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT;
1804 ts->ts_ltick = t;
1805}
1806
1807/*
1808 * Adjust the priority of a thread. Move it to the appropriate run-queue
1809 * if necessary. This is the back-end for several priority related
1810 * functions.
1811 */
1812static void
1813sched_thread_priority(struct thread *td, u_char prio)
1814{
1815 struct td_sched *ts;
1816 struct tdq *tdq;
1817 int oldpri;
1818
1819 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio",
1820 "prio:%d", td->td_priority, "new prio:%d", prio,
1821 KTR_ATTR_LINKED, sched_tdname(curthread));
1822 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio);
1823 if (td != curthread && prio < td->td_priority) {
1824 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread),
1825 "lend prio", "prio:%d", td->td_priority, "new prio:%d",
1826 prio, KTR_ATTR_LINKED, sched_tdname(td));
1827 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio,
1828 curthread);
1829 }
1830 ts = td_get_sched(td);
1831 THREAD_LOCK_ASSERT(td, MA_OWNED);
1832 if (td->td_priority == prio)
1833 return;
1834 /*
1835 * If the priority has been elevated due to priority
1836 * propagation, we may have to move ourselves to a new
1837 * queue. This could be optimized to not re-add in some
1838 * cases.
1839 */
1840 if (TD_ON_RUNQ(td) && prio < td->td_priority) {
1841 sched_rem(td);
1842 td->td_priority = prio;
1843 sched_add(td, SRQ_BORROWING | SRQ_HOLDTD);
1844 return;
1845 }
1846 /*
1847 * If the thread is currently running we may have to adjust the lowpri
1848 * information so other cpus are aware of our current priority.
1849 */
1850 if (TD_IS_RUNNING(td)) {
1851 tdq = TDQ_CPU(ts->ts_cpu);
1852 oldpri = td->td_priority;
1853 td->td_priority = prio;
1854 if (prio < tdq->tdq_lowpri)
1855 tdq->tdq_lowpri = prio;
1856 else if (tdq->tdq_lowpri == oldpri)
1857 tdq_setlowpri(tdq, td);
1858 return;
1859 }
1860 td->td_priority = prio;
1861}
1862
1863/*
1864 * Update a thread's priority when it is lent another thread's
1865 * priority.
1866 */
1867void
1868sched_lend_prio(struct thread *td, u_char prio)
1869{
1870
1871 td->td_flags |= TDF_BORROWING;
1872 sched_thread_priority(td, prio);
1873}
1874
1875/*
1876 * Restore a thread's priority when priority propagation is
1877 * over. The prio argument is the minimum priority the thread
1878 * needs to have to satisfy other possible priority lending
1879 * requests. If the thread's regular priority is less
1880 * important than prio, the thread will keep a priority boost
1881 * of prio.
1882 */
1883void
1884sched_unlend_prio(struct thread *td, u_char prio)
1885{
1886 u_char base_pri;
1887
1888 if (td->td_base_pri >= PRI_MIN_TIMESHARE &&
1889 td->td_base_pri <= PRI_MAX_TIMESHARE)
1890 base_pri = td->td_user_pri;
1891 else
1892 base_pri = td->td_base_pri;
1893 if (prio >= base_pri) {
1894 td->td_flags &= ~TDF_BORROWING;
1895 sched_thread_priority(td, base_pri);
1896 } else
1897 sched_lend_prio(td, prio);
1898}
1899
1900/*
1901 * Standard entry for setting the priority to an absolute value.
1902 */
1903void
1904sched_prio(struct thread *td, u_char prio)
1905{
1906 u_char oldprio;
1907
1908 /* First, update the base priority. */
1909 td->td_base_pri = prio;
1910
1911 /*
1912 * If the thread is borrowing another thread's priority, don't
1913 * ever lower the priority.
1914 */
1915 if (td->td_flags & TDF_BORROWING && td->td_priority < prio)
1916 return;
1917
1918 /* Change the real priority. */
1919 oldprio = td->td_priority;
1920 sched_thread_priority(td, prio);
1921
1922 /*
1923 * If the thread is on a turnstile, then let the turnstile update
1924 * its state.
1925 */
1926 if (TD_ON_LOCK(td) && oldprio != prio)
1927 turnstile_adjust(td, oldprio);
1928}
1929
1930/*
1931 * Set the base user priority, does not effect current running priority.
1932 */
1933void
1934sched_user_prio(struct thread *td, u_char prio)
1935{
1936
1937 td->td_base_user_pri = prio;
1938 if (td->td_lend_user_pri <= prio)
1939 return;
1940 td->td_user_pri = prio;
1941}
1942
1943void
1944sched_lend_user_prio(struct thread *td, u_char prio)
1945{
1946
1947 THREAD_LOCK_ASSERT(td, MA_OWNED);
1948 td->td_lend_user_pri = prio;
1949 td->td_user_pri = min(prio, td->td_base_user_pri);
1950 if (td->td_priority > td->td_user_pri)
1951 sched_prio(td, td->td_user_pri);
1952 else if (td->td_priority != td->td_user_pri)
1953 td->td_flags |= TDF_NEEDRESCHED;
1954}
1955
1956/*
1957 * Like the above but first check if there is anything to do.
1958 */
1959void
1960sched_lend_user_prio_cond(struct thread *td, u_char prio)
1961{
1962
1963 if (td->td_lend_user_pri != prio)
1964 goto lend;
1965 if (td->td_user_pri != min(prio, td->td_base_user_pri))
1966 goto lend;
1967 if (td->td_priority != td->td_user_pri)
1968 goto lend;
1969 return;
1970
1971lend:
1972 thread_lock(td);
1973 sched_lend_user_prio(td, prio);
1974 thread_unlock(td);
1975}
1976
1977#ifdef SMP
1978/*
1979 * This tdq is about to idle. Try to steal a thread from another CPU before
1980 * choosing the idle thread.
1981 */
1982static void
1983tdq_trysteal(struct tdq *tdq)
1984{
1985 struct cpu_group *cg, *parent;
1986 struct tdq *steal;
1987 cpuset_t mask;
1988 int cpu, i, goup;
1989
1990 if (smp_started == 0 || steal_idle == 0 || trysteal_limit == 0 ||
1991 tdq->tdq_cg == NULL)
1992 return;
1993 CPU_FILL(&mask);
1994 CPU_CLR(PCPU_GET(cpuid), &mask);
1995 /* We don't want to be preempted while we're iterating. */
1996 spinlock_enter();
1997 TDQ_UNLOCK(tdq);
1998 for (i = 1, cg = tdq->tdq_cg, goup = 0; ; ) {
1999 cpu = sched_highest(cg, &mask, steal_thresh, 1);
2000 /*
2001 * If a thread was added while interrupts were disabled don't
2002 * steal one here.
2003 */
2004 if (tdq->tdq_load > 0) {
2005 TDQ_LOCK(tdq);
2006 break;
2007 }
2008
2009 /*
2010 * We found no CPU to steal from in this group. Escalate to
2011 * the parent and repeat. But if parent has only two children
2012 * groups we can avoid searching this group again by searching
2013 * the other one specifically and then escalating two levels.
2014 */
2015 if (cpu == -1) {
2016 if (goup) {
2017 cg = cg->cg_parent;
2018 goup = 0;
2019 }
2020 if (++i > trysteal_limit) {
2021 TDQ_LOCK(tdq);
2022 break;
2023 }
2024 parent = cg->cg_parent;
2025 if (parent == NULL) {
2026 TDQ_LOCK(tdq);
2027 break;
2028 }
2029 if (parent->cg_children == 2) {
2030 if (cg == &parent->cg_child[0])
2031 cg = &parent->cg_child[1];
2032 else
2033 cg = &parent->cg_child[0];
2034 goup = 1;
2035 } else
2036 cg = parent;
2037 continue;
2038 }
2039 steal = TDQ_CPU(cpu);
2040 /*
2041 * The data returned by sched_highest() is stale and
2042 * the chosen CPU no longer has an eligible thread.
2043 * At this point unconditionally exit the loop to bound
2044 * the time spent in the critcal section.
2045 */
2046 if (steal->tdq_load < steal_thresh ||
2047 steal->tdq_transferable == 0)
2048 continue;
2049 /*
2050 * Try to lock both queues. If we are assigned a thread while
2051 * waited for the lock, switch to it now instead of stealing.
2052 * If we can't get the lock, then somebody likely got there
2053 * first.
2054 */
2055 TDQ_LOCK(tdq);
2056 if (tdq->tdq_load > 0)
2057 break;
2058 if (TDQ_TRYLOCK_FLAGS(steal, MTX_DUPOK) == 0)
2059 break;
2060 /*
2061 * The data returned by sched_highest() is stale and
2062 * the chosen CPU no longer has an eligible thread.
2063 */
2064 if (steal->tdq_load < steal_thresh ||
2065 steal->tdq_transferable == 0) {
2066 TDQ_UNLOCK(steal);
2067 break;
2068 }
2069 /*
2070 * If we fail to acquire one due to affinity restrictions,
2071 * bail out and let the idle thread to a more complete search
2072 * outside of a critical section.
2073 */
2074 if (tdq_move(steal, tdq) == NULL) {
2075 TDQ_UNLOCK(steal);
2076 break;
2077 }
2078 TDQ_UNLOCK(steal);
2079 break;
2080 }
2081 spinlock_exit();
2082}
2083#endif
2084
2085/*
2086 * Handle migration from sched_switch(). This happens only for
2087 * cpu binding.
2088 */
2089static struct mtx *
2090sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags)
2091{
2092 struct tdq *tdn;
2093
2094 KASSERT(THREAD_CAN_MIGRATE(td) ||
2095 (td_get_sched(td)->ts_flags & TSF_BOUND) != 0,
2096 ("Thread %p shouldn't migrate", td));
2097 KASSERT(!CPU_ABSENT(td_get_sched(td)->ts_cpu), ("sched_switch_migrate: "
2098 "thread %s queued on absent CPU %d.", td->td_name,
2099 td_get_sched(td)->ts_cpu));
2100 tdn = TDQ_CPU(td_get_sched(td)->ts_cpu);
2101#ifdef SMP
2102 tdq_load_rem(tdq, td);
2103 /*
2104 * Do the lock dance required to avoid LOR. We have an
2105 * extra spinlock nesting from sched_switch() which will
2106 * prevent preemption while we're holding neither run-queue lock.
2107 */
2108 TDQ_UNLOCK(tdq);
2109 TDQ_LOCK(tdn);
2110 tdq_add(tdn, td, flags);
2111 tdq_notify(tdn, td);
2112 TDQ_UNLOCK(tdn);
2113 TDQ_LOCK(tdq);
2114#endif
2115 return (TDQ_LOCKPTR(tdn));
2116}
2117
2118/*
2119 * thread_lock_unblock() that does not assume td_lock is blocked.
2120 */
2121static inline void
2122thread_unblock_switch(struct thread *td, struct mtx *mtx)
2123{
2124 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock,
2125 (uintptr_t)mtx);
2126}
2127
2128/*
2129 * Switch threads. This function has to handle threads coming in while
2130 * blocked for some reason, running, or idle. It also must deal with
2131 * migrating a thread from one queue to another as running threads may
2132 * be assigned elsewhere via binding.
2133 */
2134void
2135sched_switch(struct thread *td, int flags)
2136{
2137 struct thread *newtd;
2138 struct tdq *tdq;
2139 struct td_sched *ts;
2140 struct mtx *mtx;
2141 int srqflag;
2142 int cpuid, preempted;
2143#ifdef SMP
2144 int pickcpu;
2145#endif
2146
2147 THREAD_LOCK_ASSERT(td, MA_OWNED);
2148
2149 cpuid = PCPU_GET(cpuid);
2150 tdq = TDQ_SELF();
2151 ts = td_get_sched(td);
2152 sched_pctcpu_update(ts, 1);
2153#ifdef SMP
2154 pickcpu = (td->td_flags & TDF_PICKCPU) != 0;
2155 if (pickcpu)
2156 ts->ts_rltick = ticks - affinity * MAX_CACHE_LEVELS;
2157 else
2158 ts->ts_rltick = ticks;
2159#endif
2160 td->td_lastcpu = td->td_oncpu;
2161 preempted = (td->td_flags & TDF_SLICEEND) == 0 &&
2162 (flags & SW_PREEMPT) != 0;
2163 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_PICKCPU | TDF_SLICEEND);
2164 td->td_owepreempt = 0;
2165 tdq->tdq_owepreempt = 0;
2166 if (!TD_IS_IDLETHREAD(td))
2167 tdq->tdq_switchcnt++;
2168
2169 /*
2170 * Always block the thread lock so we can drop the tdq lock early.
2171 */
2172 mtx = thread_lock_block(td);
2173 spinlock_enter();
2174 if (TD_IS_IDLETHREAD(td)) {
2175 MPASS(mtx == TDQ_LOCKPTR(tdq));
2176 TD_SET_CAN_RUN(td);
2177 } else if (TD_IS_RUNNING(td)) {
2178 MPASS(mtx == TDQ_LOCKPTR(tdq));
2179 srqflag = preempted ?
2180 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
2181 SRQ_OURSELF|SRQ_YIELDING;
2182#ifdef SMP
2183 if (THREAD_CAN_MIGRATE(td) && (!THREAD_CAN_SCHED(td, ts->ts_cpu)
2184 || pickcpu))
2185 ts->ts_cpu = sched_pickcpu(td, 0);
2186#endif
2187 if (ts->ts_cpu == cpuid)
2188 tdq_runq_add(tdq, td, srqflag);
2189 else
2190 mtx = sched_switch_migrate(tdq, td, srqflag);
2191 } else {
2192 /* This thread must be going to sleep. */
2193 if (mtx != TDQ_LOCKPTR(tdq)) {
2194 mtx_unlock_spin(mtx);
2195 TDQ_LOCK(tdq);
2196 }
2197 tdq_load_rem(tdq, td);
2198#ifdef SMP
2199 if (tdq->tdq_load == 0)
2200 tdq_trysteal(tdq);
2201#endif
2202 }
2203
2204#if (KTR_COMPILE & KTR_SCHED) != 0
2205 if (TD_IS_IDLETHREAD(td))
2206 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle",
2207 "prio:%d", td->td_priority);
2208 else
2209 KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td),
2210 "prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg,
2211 "lockname:\"%s\"", td->td_lockname);
2212#endif
2213
2214 /*
2215 * We enter here with the thread blocked and assigned to the
2216 * appropriate cpu run-queue or sleep-queue and with the current
2217 * thread-queue locked.
2218 */
2219 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED);
2220 newtd = choosethread();
2221 sched_pctcpu_update(td_get_sched(newtd), 0);
2222 TDQ_UNLOCK(tdq);
2223
2224 /*
2225 * Call the MD code to switch contexts if necessary.
2226 */
2227 if (td != newtd) {
2228#ifdef HWPMC_HOOKS
2229 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
2230 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
2231#endif
2232 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc);
2233
2234#ifdef KDTRACE_HOOKS
2235 /*
2236 * If DTrace has set the active vtime enum to anything
2237 * other than INACTIVE (0), then it should have set the
2238 * function to call.
2239 */
2240 if (dtrace_vtime_active)
2241 (*dtrace_vtime_switch_func)(newtd);
2242#endif
2243 td->td_oncpu = NOCPU;
2244 cpu_switch(td, newtd, mtx);
2245 cpuid = td->td_oncpu = PCPU_GET(cpuid);
2246
2247 SDT_PROBE0(sched, , , on__cpu);
2248#ifdef HWPMC_HOOKS
2249 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
2250 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
2251#endif
2252 } else {
2253 thread_unblock_switch(td, mtx);
2254 SDT_PROBE0(sched, , , remain__cpu);
2255 }
2256 KASSERT(curthread->td_md.md_spinlock_count == 1,
2257 ("invalid count %d", curthread->td_md.md_spinlock_count));
2258
2259 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running",
2260 "prio:%d", td->td_priority);
2261}
2262
2263/*
2264 * Adjust thread priorities as a result of a nice request.
2265 */
2266void
2267sched_nice(struct proc *p, int nice)
2268{
2269 struct thread *td;
2270
2271 PROC_LOCK_ASSERT(p, MA_OWNED);
2272
2273 p->p_nice = nice;
2274 FOREACH_THREAD_IN_PROC(p, td) {
2275 thread_lock(td);
2276 sched_priority(td);
2277 sched_prio(td, td->td_base_user_pri);
2278 thread_unlock(td);
2279 }
2280}
2281
2282/*
2283 * Record the sleep time for the interactivity scorer.
2284 */
2285void
2286sched_sleep(struct thread *td, int prio)
2287{
2288
2289 THREAD_LOCK_ASSERT(td, MA_OWNED);
2290
2291 td->td_slptick = ticks;
2292 if (TD_IS_SUSPENDED(td) || prio >= PSOCK)
2293 td->td_flags |= TDF_CANSWAP;
2294 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE)
2295 return;
2296 if (static_boost == 1 && prio)
2297 sched_prio(td, prio);
2298 else if (static_boost && td->td_priority > static_boost)
2299 sched_prio(td, static_boost);
2300}
2301
2302/*
2303 * Schedule a thread to resume execution and record how long it voluntarily
2304 * slept. We also update the pctcpu, interactivity, and priority.
2305 *
2306 * Requires the thread lock on entry, drops on exit.
2307 */
2308void
2309sched_wakeup(struct thread *td, int srqflags)
2310{
2311 struct td_sched *ts;
2312 int slptick;
2313
2314 THREAD_LOCK_ASSERT(td, MA_OWNED);
2315 ts = td_get_sched(td);
2316 td->td_flags &= ~TDF_CANSWAP;
2317
2318 /*
2319 * If we slept for more than a tick update our interactivity and
2320 * priority.
2321 */
2322 slptick = td->td_slptick;
2323 td->td_slptick = 0;
2324 if (slptick && slptick != ticks) {
2325 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT;
2326 sched_interact_update(td);
2327 sched_pctcpu_update(ts, 0);
2328 }
2329 /*
2330 * Reset the slice value since we slept and advanced the round-robin.
2331 */
2332 ts->ts_slice = 0;
2333 sched_add(td, SRQ_BORING | srqflags);
2334}
2335
2336/*
2337 * Penalize the parent for creating a new child and initialize the child's
2338 * priority.
2339 */
2340void
2341sched_fork(struct thread *td, struct thread *child)
2342{
2343 THREAD_LOCK_ASSERT(td, MA_OWNED);
2344 sched_pctcpu_update(td_get_sched(td), 1);
2345 sched_fork_thread(td, child);
2346 /*
2347 * Penalize the parent and child for forking.
2348 */
2349 sched_interact_fork(child);
2350 sched_priority(child);
2351 td_get_sched(td)->ts_runtime += tickincr;
2352 sched_interact_update(td);
2353 sched_priority(td);
2354}
2355
2356/*
2357 * Fork a new thread, may be within the same process.
2358 */
2359void
2360sched_fork_thread(struct thread *td, struct thread *child)
2361{
2362 struct td_sched *ts;
2363 struct td_sched *ts2;
2364 struct tdq *tdq;
2365
2366 tdq = TDQ_SELF();
2367 THREAD_LOCK_ASSERT(td, MA_OWNED);
2368 /*
2369 * Initialize child.
2370 */
2371 ts = td_get_sched(td);
2372 ts2 = td_get_sched(child);
2373 child->td_oncpu = NOCPU;
2374 child->td_lastcpu = NOCPU;
2375 child->td_lock = TDQ_LOCKPTR(tdq);
2376 child->td_cpuset = cpuset_ref(td->td_cpuset);
2377 child->td_domain.dr_policy = td->td_cpuset->cs_domain;
2378 ts2->ts_cpu = ts->ts_cpu;
2379 ts2->ts_flags = 0;
2380 /*
2381 * Grab our parents cpu estimation information.
2382 */
2383 ts2->ts_ticks = ts->ts_ticks;
2384 ts2->ts_ltick = ts->ts_ltick;
2385 ts2->ts_ftick = ts->ts_ftick;
2386 /*
2387 * Do not inherit any borrowed priority from the parent.
2388 */
2389 child->td_priority = child->td_base_pri;
2390 /*
2391 * And update interactivity score.
2392 */
2393 ts2->ts_slptime = ts->ts_slptime;
2394 ts2->ts_runtime = ts->ts_runtime;
2395 /* Attempt to quickly learn interactivity. */
2396 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min;
2397#ifdef KTR
2398 bzero(ts2->ts_name, sizeof(ts2->ts_name));
2399#endif
2400}
2401
2402/*
2403 * Adjust the priority class of a thread.
2404 */
2405void
2406sched_class(struct thread *td, int class)
2407{
2408
2409 THREAD_LOCK_ASSERT(td, MA_OWNED);
2410 if (td->td_pri_class == class)
2411 return;
2412 td->td_pri_class = class;
2413}
2414
2415/*
2416 * Return some of the child's priority and interactivity to the parent.
2417 */
2418void
2419sched_exit(struct proc *p, struct thread *child)
2420{
2421 struct thread *td;
2422
2423 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit",
2424 "prio:%d", child->td_priority);
2425 PROC_LOCK_ASSERT(p, MA_OWNED);
2426 td = FIRST_THREAD_IN_PROC(p);
2427 sched_exit_thread(td, child);
2428}
2429
2430/*
2431 * Penalize another thread for the time spent on this one. This helps to
2432 * worsen the priority and interactivity of processes which schedule batch
2433 * jobs such as make. This has little effect on the make process itself but
2434 * causes new processes spawned by it to receive worse scores immediately.
2435 */
2436void
2437sched_exit_thread(struct thread *td, struct thread *child)
2438{
2439
2440 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit",
2441 "prio:%d", child->td_priority);
2442 /*
2443 * Give the child's runtime to the parent without returning the
2444 * sleep time as a penalty to the parent. This causes shells that
2445 * launch expensive things to mark their children as expensive.
2446 */
2447 thread_lock(td);
2448 td_get_sched(td)->ts_runtime += td_get_sched(child)->ts_runtime;
2449 sched_interact_update(td);
2450 sched_priority(td);
2451 thread_unlock(td);
2452}
2453
2454void
2455sched_preempt(struct thread *td)
2456{
2457 struct tdq *tdq;
2458 int flags;
2459
2460 SDT_PROBE2(sched, , , surrender, td, td->td_proc);
2461
2462 thread_lock(td);
2463 tdq = TDQ_SELF();
2464 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2465 if (td->td_priority > tdq->tdq_lowpri) {
2466 if (td->td_critnest == 1) {
2467 flags = SW_INVOL | SW_PREEMPT;
2468 flags |= TD_IS_IDLETHREAD(td) ? SWT_REMOTEWAKEIDLE :
2469 SWT_REMOTEPREEMPT;
2470 mi_switch(flags);
2471 /* Switch dropped thread lock. */
2472 return;
2473 }
2474 td->td_owepreempt = 1;
2475 } else {
2476 tdq->tdq_owepreempt = 0;
2477 }
2478 thread_unlock(td);
2479}
2480
2481/*
2482 * Fix priorities on return to user-space. Priorities may be elevated due
2483 * to static priorities in msleep() or similar.
2484 */
2485void
2486sched_userret_slowpath(struct thread *td)
2487{
2488
2489 thread_lock(td);
2490 td->td_priority = td->td_user_pri;
2491 td->td_base_pri = td->td_user_pri;
2492 tdq_setlowpri(TDQ_SELF(), td);
2493 thread_unlock(td);
2494}
2495
2496/*
2497 * Handle a stathz tick. This is really only relevant for timeshare
2498 * threads.
2499 */
2500void
2501sched_clock(struct thread *td, int cnt)
2502{
2503 struct tdq *tdq;
2504 struct td_sched *ts;
2505
2506 THREAD_LOCK_ASSERT(td, MA_OWNED);
2507 tdq = TDQ_SELF();
2508#ifdef SMP
2509 /*
2510 * We run the long term load balancer infrequently on the first cpu.
2511 */
2512 if (balance_tdq == tdq && smp_started != 0 && rebalance != 0 &&
2513 balance_ticks != 0) {
2514 balance_ticks -= cnt;
2515 if (balance_ticks <= 0)
2516 sched_balance();
2517 }
2518#endif
2519 /*
2520 * Save the old switch count so we have a record of the last ticks
2521 * activity. Initialize the new switch count based on our load.
2522 * If there is some activity seed it to reflect that.
2523 */
2524 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt;
2525 tdq->tdq_switchcnt = tdq->tdq_load;
2526 /*
2527 * Advance the insert index once for each tick to ensure that all
2528 * threads get a chance to run.
2529 */
2530 if (tdq->tdq_idx == tdq->tdq_ridx) {
2531 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS;
2532 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx]))
2533 tdq->tdq_ridx = tdq->tdq_idx;
2534 }
2535 ts = td_get_sched(td);
2536 sched_pctcpu_update(ts, 1);
2537 if ((td->td_pri_class & PRI_FIFO_BIT) || TD_IS_IDLETHREAD(td))
2538 return;
2539
2540 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) {
2541 /*
2542 * We used a tick; charge it to the thread so
2543 * that we can compute our interactivity.
2544 */
2545 td_get_sched(td)->ts_runtime += tickincr * cnt;
2546 sched_interact_update(td);
2547 sched_priority(td);
2548 }
2549
2550 /*
2551 * Force a context switch if the current thread has used up a full
2552 * time slice (default is 100ms).
2553 */
2554 ts->ts_slice += cnt;
2555 if (ts->ts_slice >= tdq_slice(tdq)) {
2556 ts->ts_slice = 0;
2557 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND;
2558 }
2559}
2560
2561u_int
2562sched_estcpu(struct thread *td __unused)
2563{
2564
2565 return (0);
2566}
2567
2568/*
2569 * Return whether the current CPU has runnable tasks. Used for in-kernel
2570 * cooperative idle threads.
2571 */
2572int
2573sched_runnable(void)
2574{
2575 struct tdq *tdq;
2576 int load;
2577
2578 load = 1;
2579
2580 tdq = TDQ_SELF();
2581 if ((curthread->td_flags & TDF_IDLETD) != 0) {
2582 if (tdq->tdq_load > 0)
2583 goto out;
2584 } else
2585 if (tdq->tdq_load - 1 > 0)
2586 goto out;
2587 load = 0;
2588out:
2589 return (load);
2590}
2591
2592/*
2593 * Choose the highest priority thread to run. The thread is removed from
2594 * the run-queue while running however the load remains. For SMP we set
2595 * the tdq in the global idle bitmask if it idles here.
2596 */
2597struct thread *
2598sched_choose(void)
2599{
2600 struct thread *td;
2601 struct tdq *tdq;
2602
2603 tdq = TDQ_SELF();
2604 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2605 td = tdq_choose(tdq);
2606 if (td) {
2607 tdq_runq_rem(tdq, td);
2608 tdq->tdq_lowpri = td->td_priority;
2609 return (td);
2610 }
2611 tdq->tdq_lowpri = PRI_MAX_IDLE;
2612 return (PCPU_GET(idlethread));
2613}
2614
2615/*
2616 * Set owepreempt if necessary. Preemption never happens directly in ULE,
2617 * we always request it once we exit a critical section.
2618 */
2619static inline void
2620sched_setpreempt(struct thread *td)
2621{
2622 struct thread *ctd;
2623 int cpri;
2624 int pri;
2625
2626 THREAD_LOCK_ASSERT(curthread, MA_OWNED);
2627
2628 ctd = curthread;
2629 pri = td->td_priority;
2630 cpri = ctd->td_priority;
2631 if (pri < cpri)
2632 ctd->td_flags |= TDF_NEEDRESCHED;
2633 if (KERNEL_PANICKED() || pri >= cpri || cold || TD_IS_INHIBITED(ctd))
2634 return;
2635 if (!sched_shouldpreempt(pri, cpri, 0))
2636 return;
2637 ctd->td_owepreempt = 1;
2638}
2639
2640/*
2641 * Add a thread to a thread queue. Select the appropriate runq and add the
2642 * thread to it. This is the internal function called when the tdq is
2643 * predetermined.
2644 */
2645void
2646tdq_add(struct tdq *tdq, struct thread *td, int flags)
2647{
2648
2649 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2650 THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED);
2651 KASSERT((td->td_inhibitors == 0),
2652 ("sched_add: trying to run inhibited thread"));
2653 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
2654 ("sched_add: bad thread state"));
2655 KASSERT(td->td_flags & TDF_INMEM,
2656 ("sched_add: thread swapped out"));
2657
2658 if (td->td_priority < tdq->tdq_lowpri)
2659 tdq->tdq_lowpri = td->td_priority;
2660 tdq_runq_add(tdq, td, flags);
2661 tdq_load_add(tdq, td);
2662}
2663
2664/*
2665 * Select the target thread queue and add a thread to it. Request
2666 * preemption or IPI a remote processor if required.
2667 *
2668 * Requires the thread lock on entry, drops on exit.
2669 */
2670void
2671sched_add(struct thread *td, int flags)
2672{
2673 struct tdq *tdq;
2674#ifdef SMP
2675 int cpu;
2676#endif
2677
2678 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
2679 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
2680 sched_tdname(curthread));
2681 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
2682 KTR_ATTR_LINKED, sched_tdname(td));
2683 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL,
2684 flags & SRQ_PREEMPTED);
2685 THREAD_LOCK_ASSERT(td, MA_OWNED);
2686 /*
2687 * Recalculate the priority before we select the target cpu or
2688 * run-queue.
2689 */
2690 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
2691 sched_priority(td);
2692#ifdef SMP
2693 /*
2694 * Pick the destination cpu and if it isn't ours transfer to the
2695 * target cpu.
2696 */
2697 cpu = sched_pickcpu(td, flags);
2698 tdq = sched_setcpu(td, cpu, flags);
2699 tdq_add(tdq, td, flags);
2700 if (cpu != PCPU_GET(cpuid))
2701 tdq_notify(tdq, td);
2702 else if (!(flags & SRQ_YIELDING))
2703 sched_setpreempt(td);
2704#else
2705 tdq = TDQ_SELF();
2706 /*
2707 * Now that the thread is moving to the run-queue, set the lock
2708 * to the scheduler's lock.
2709 */
2710 if (td->td_lock != TDQ_LOCKPTR(tdq)) {
2711 TDQ_LOCK(tdq);
2712 if ((flags & SRQ_HOLD) != 0)
2713 td->td_lock = TDQ_LOCKPTR(tdq);
2714 else
2715 thread_lock_set(td, TDQ_LOCKPTR(tdq));
2716 }
2717 tdq_add(tdq, td, flags);
2718 if (!(flags & SRQ_YIELDING))
2719 sched_setpreempt(td);
2720#endif
2721 if (!(flags & SRQ_HOLDTD))
2722 thread_unlock(td);
2723}
2724
2725/*
2726 * Remove a thread from a run-queue without running it. This is used
2727 * when we're stealing a thread from a remote queue. Otherwise all threads
2728 * exit by calling sched_exit_thread() and sched_throw() themselves.
2729 */
2730void
2731sched_rem(struct thread *td)
2732{
2733 struct tdq *tdq;
2734
2735 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem",
2736 "prio:%d", td->td_priority);
2737 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL);
2738 tdq = TDQ_CPU(td_get_sched(td)->ts_cpu);
2739 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2740 MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2741 KASSERT(TD_ON_RUNQ(td),
2742 ("sched_rem: thread not on run queue"));
2743 tdq_runq_rem(tdq, td);
2744 tdq_load_rem(tdq, td);
2745 TD_SET_CAN_RUN(td);
2746 if (td->td_priority == tdq->tdq_lowpri)
2747 tdq_setlowpri(tdq, NULL);
2748}
2749
2750/*
2751 * Fetch cpu utilization information. Updates on demand.
2752 */
2753fixpt_t
2754sched_pctcpu(struct thread *td)
2755{
2756 fixpt_t pctcpu;
2757 struct td_sched *ts;
2758
2759 pctcpu = 0;
2760 ts = td_get_sched(td);
2761
2762 THREAD_LOCK_ASSERT(td, MA_OWNED);
2763 sched_pctcpu_update(ts, TD_IS_RUNNING(td));
2764 if (ts->ts_ticks) {
2765 int rtick;
2766
2767 /* How many rtick per second ? */
2768 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz);
2769 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT;
2770 }
2771
2772 return (pctcpu);
2773}
2774
2775/*
2776 * Enforce affinity settings for a thread. Called after adjustments to
2777 * cpumask.
2778 */
2779void
2780sched_affinity(struct thread *td)
2781{
2782#ifdef SMP
2783 struct td_sched *ts;
2784
2785 THREAD_LOCK_ASSERT(td, MA_OWNED);
2786 ts = td_get_sched(td);
2787 if (THREAD_CAN_SCHED(td, ts->ts_cpu))
2788 return;
2789 if (TD_ON_RUNQ(td)) {
2790 sched_rem(td);
2791 sched_add(td, SRQ_BORING | SRQ_HOLDTD);
2792 return;
2793 }
2794 if (!TD_IS_RUNNING(td))
2795 return;
2796 /*
2797 * Force a switch before returning to userspace. If the
2798 * target thread is not running locally send an ipi to force
2799 * the issue.
2800 */
2801 td->td_flags |= TDF_NEEDRESCHED;
2802 if (td != curthread)
2803 ipi_cpu(ts->ts_cpu, IPI_PREEMPT);
2804#endif
2805}
2806
2807/*
2808 * Bind a thread to a target cpu.
2809 */
2810void
2811sched_bind(struct thread *td, int cpu)
2812{
2813 struct td_sched *ts;
2814
2815 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED);
2816 KASSERT(td == curthread, ("sched_bind: can only bind curthread"));
2817 ts = td_get_sched(td);
2818 if (ts->ts_flags & TSF_BOUND)
2819 sched_unbind(td);
2820 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td));
2821 ts->ts_flags |= TSF_BOUND;
2822 sched_pin();
2823 if (PCPU_GET(cpuid) == cpu)
2824 return;
2825 ts->ts_cpu = cpu;
2826 /* When we return from mi_switch we'll be on the correct cpu. */
2827 mi_switch(SW_VOL);
2828 thread_lock(td);
2829}
2830
2831/*
2832 * Release a bound thread.
2833 */
2834void
2835sched_unbind(struct thread *td)
2836{
2837 struct td_sched *ts;
2838
2839 THREAD_LOCK_ASSERT(td, MA_OWNED);
2840 KASSERT(td == curthread, ("sched_unbind: can only bind curthread"));
2841 ts = td_get_sched(td);
2842 if ((ts->ts_flags & TSF_BOUND) == 0)
2843 return;
2844 ts->ts_flags &= ~TSF_BOUND;
2845 sched_unpin();
2846}
2847
2848int
2849sched_is_bound(struct thread *td)
2850{
2851 THREAD_LOCK_ASSERT(td, MA_OWNED);
2852 return (td_get_sched(td)->ts_flags & TSF_BOUND);
2853}
2854
2855/*
2856 * Basic yield call.
2857 */
2858void
2859sched_relinquish(struct thread *td)
2860{
2861 thread_lock(td);
2862 mi_switch(SW_VOL | SWT_RELINQUISH);
2863}
2864
2865/*
2866 * Return the total system load.
2867 */
2868int
2869sched_load(void)
2870{
2871#ifdef SMP
2872 int total;
2873 int i;
2874
2875 total = 0;
2876 CPU_FOREACH(i)
2877 total += TDQ_CPU(i)->tdq_sysload;
2878 return (total);
2879#else
2880 return (TDQ_SELF()->tdq_sysload);
2881#endif
2882}
2883
2884int
2885sched_sizeof_proc(void)
2886{
2887 return (sizeof(struct proc));
2888}
2889
2890int
2891sched_sizeof_thread(void)
2892{
2893 return (sizeof(struct thread) + sizeof(struct td_sched));
2894}
2895
2896#ifdef SMP
2897#define TDQ_IDLESPIN(tdq) \
2898 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0)
2899#else
2900#define TDQ_IDLESPIN(tdq) 1
2901#endif
2902
2903/*
2904 * The actual idle process.
2905 */
2906void
2907sched_idletd(void *dummy)
2908{
2909 struct thread *td;
2910 struct tdq *tdq;
2911 int oldswitchcnt, switchcnt;
2912 int i;
2913
2914 mtx_assert(&Giant, MA_NOTOWNED);
2915 td = curthread;
2916 tdq = TDQ_SELF();
2917 THREAD_NO_SLEEPING();
2918 oldswitchcnt = -1;
2919 for (;;) {
2920 if (tdq->tdq_load) {
2921 thread_lock(td);
2922 mi_switch(SW_VOL | SWT_IDLE);
2923 }
2924 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2925#ifdef SMP
2926 if (always_steal || switchcnt != oldswitchcnt) {
2927 oldswitchcnt = switchcnt;
2928 if (tdq_idled(tdq) == 0)
2929 continue;
2930 }
2931 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2932#else
2933 oldswitchcnt = switchcnt;
2934#endif
2935 /*
2936 * If we're switching very frequently, spin while checking
2937 * for load rather than entering a low power state that
2938 * may require an IPI. However, don't do any busy
2939 * loops while on SMT machines as this simply steals
2940 * cycles from cores doing useful work.
2941 */
2942 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) {
2943 for (i = 0; i < sched_idlespins; i++) {
2944 if (tdq->tdq_load)
2945 break;
2946 cpu_spinwait();
2947 }
2948 }
2949
2950 /* If there was context switch during spin, restart it. */
2951 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2952 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt)
2953 continue;
2954
2955 /* Run main MD idle handler. */
2956 tdq->tdq_cpu_idle = 1;
2957 /*
2958 * Make sure that tdq_cpu_idle update is globally visible
2959 * before cpu_idle() read tdq_load. The order is important
2960 * to avoid race with tdq_notify.
2961 */
2962 atomic_thread_fence_seq_cst();
2963 /*
2964 * Checking for again after the fence picks up assigned
2965 * threads often enough to make it worthwhile to do so in
2966 * order to avoid calling cpu_idle().
2967 */
2968 if (tdq->tdq_load != 0) {
2969 tdq->tdq_cpu_idle = 0;
2970 continue;
2971 }
2972 cpu_idle(switchcnt * 4 > sched_idlespinthresh);
2973 tdq->tdq_cpu_idle = 0;
2974
2975 /*
2976 * Account thread-less hardware interrupts and
2977 * other wakeup reasons equal to context switches.
2978 */
2979 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2980 if (switchcnt != oldswitchcnt)
2981 continue;
2982 tdq->tdq_switchcnt++;
2983 oldswitchcnt++;
2984 }
2985}
2986
2987/*
2988 * sched_throw_grab() chooses a thread from the queue to switch to
2989 * next. It returns with the tdq lock dropped in a spinlock section to
2990 * keep interrupts disabled until the CPU is running in a proper threaded
2991 * context.
2992 */
2993static struct thread *
2994sched_throw_grab(struct tdq *tdq)
2995{
2996 struct thread *newtd;
2997
2998 newtd = choosethread();
2999 spinlock_enter();
3000 TDQ_UNLOCK(tdq);
3001 KASSERT(curthread->td_md.md_spinlock_count == 1,
3002 ("invalid count %d", curthread->td_md.md_spinlock_count));
3003 return (newtd);
3004}
3005
3006/*
3007 * A CPU is entering for the first time.
3008 */
3009void
3010sched_ap_entry(void)
3011{
3012 struct thread *newtd;
3013 struct tdq *tdq;
3014
3015 tdq = TDQ_SELF();
3016
3017 /* This should have been setup in schedinit_ap(). */
3018 THREAD_LOCKPTR_ASSERT(curthread, TDQ_LOCKPTR(tdq));
3019
3020 TDQ_LOCK(tdq);
3021 /* Correct spinlock nesting. */
3022 spinlock_exit();
3023 PCPU_SET(switchtime, cpu_ticks());
3024 PCPU_SET(switchticks, ticks);
3025
3026 newtd = sched_throw_grab(tdq);
3027
3028 /* doesn't return */
3029 cpu_throw(NULL, newtd);
3030}
3031
3032/*
3033 * A thread is exiting.
3034 */
3035void
3036sched_throw(struct thread *td)
3037{
3038 struct thread *newtd;
3039 struct tdq *tdq;
3040
3041 tdq = TDQ_SELF();
3042
3043 MPASS(td != NULL);
3044 THREAD_LOCK_ASSERT(td, MA_OWNED);
3045 THREAD_LOCKPTR_ASSERT(td, TDQ_LOCKPTR(tdq));
3046
3047 tdq_load_rem(tdq, td);
3048 td->td_lastcpu = td->td_oncpu;
3049 td->td_oncpu = NOCPU;
3050 thread_lock_block(td);
3051
3052 newtd = sched_throw_grab(tdq);
3053
3054 /* doesn't return */
3055 cpu_switch(td, newtd, TDQ_LOCKPTR(tdq));
3056}
3057
3058/*
3059 * This is called from fork_exit(). Just acquire the correct locks and
3060 * let fork do the rest of the work.
3061 */
3062void
3063sched_fork_exit(struct thread *td)
3064{
3065 struct tdq *tdq;
3066 int cpuid;
3067
3068 /*
3069 * Finish setting up thread glue so that it begins execution in a
3070 * non-nested critical section with the scheduler lock held.
3071 */
3072 KASSERT(curthread->td_md.md_spinlock_count == 1,
3073 ("invalid count %d", curthread->td_md.md_spinlock_count));
3074 cpuid = PCPU_GET(cpuid);
3075 tdq = TDQ_SELF();
3076 TDQ_LOCK(tdq);
3077 spinlock_exit();
3078 MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
3079 td->td_oncpu = cpuid;
3080 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running",
3081 "prio:%d", td->td_priority);
3082 SDT_PROBE0(sched, , , on__cpu);
3083}
3084
3085/*
3086 * Create on first use to catch odd startup conditions.
3087 */
3088char *
3089sched_tdname(struct thread *td)
3090{
3091#ifdef KTR
3092 struct td_sched *ts;
3093
3094 ts = td_get_sched(td);
3095 if (ts->ts_name[0] == '\0')
3096 snprintf(ts->ts_name, sizeof(ts->ts_name),
3097 "%s tid %d", td->td_name, td->td_tid);
3098 return (ts->ts_name);
3099#else
3100 return (td->td_name);
3101#endif
3102}
3103
3104#ifdef KTR
3105void
3106sched_clear_tdname(struct thread *td)
3107{
3108 struct td_sched *ts;
3109
3110 ts = td_get_sched(td);
3111 ts->ts_name[0] = '\0';
3112}
3113#endif
3114
3115#ifdef SMP
3116
3117/*
3118 * Build the CPU topology dump string. Is recursively called to collect
3119 * the topology tree.
3120 */
3121static int
3122sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg,
3123 int indent)
3124{
3125 char cpusetbuf[CPUSETBUFSIZ];
3126 int i, first;
3127
3128 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent,
3129 "", 1 + indent / 2, cg->cg_level);
3130 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "",
3131 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask));
3132 first = TRUE;
3133 for (i = cg->cg_first; i <= cg->cg_last; i++) {
3134 if (CPU_ISSET(i, &cg->cg_mask)) {
3135 if (!first)
3136 sbuf_printf(sb, ", ");
3137 else
3138 first = FALSE;
3139 sbuf_printf(sb, "%d", i);
3140 }
3141 }
3142 sbuf_printf(sb, "</cpu>\n");
3143
3144 if (cg->cg_flags != 0) {
3145 sbuf_printf(sb, "%*s <flags>", indent, "");
3146 if ((cg->cg_flags & CG_FLAG_HTT) != 0)
3147 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>");
3148 if ((cg->cg_flags & CG_FLAG_THREAD) != 0)
3149 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>");
3150 if ((cg->cg_flags & CG_FLAG_SMT) != 0)
3151 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>");
3152 if ((cg->cg_flags & CG_FLAG_NODE) != 0)
3153 sbuf_printf(sb, "<flag name=\"NODE\">NUMA node</flag>");
3154 sbuf_printf(sb, "</flags>\n");
3155 }
3156
3157 if (cg->cg_children > 0) {
3158 sbuf_printf(sb, "%*s <children>\n", indent, "");
3159 for (i = 0; i < cg->cg_children; i++)
3160 sysctl_kern_sched_topology_spec_internal(sb,
3161 &cg->cg_child[i], indent+2);
3162 sbuf_printf(sb, "%*s </children>\n", indent, "");
3163 }
3164 sbuf_printf(sb, "%*s</group>\n", indent, "");
3165 return (0);
3166}
3167
3168/*
3169 * Sysctl handler for retrieving topology dump. It's a wrapper for
3170 * the recursive sysctl_kern_smp_topology_spec_internal().
3171 */
3172static int
3173sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS)
3174{
3175 struct sbuf *topo;
3176 int err;
3177
3178 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized"));
3179
3180 topo = sbuf_new_for_sysctl(NULL, NULL, 512, req);
3181 if (topo == NULL)
3182 return (ENOMEM);
3183
3184 sbuf_printf(topo, "<groups>\n");
3185 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1);
3186 sbuf_printf(topo, "</groups>\n");
3187
3188 if (err == 0) {
3189 err = sbuf_finish(topo);
3190 }
3191 sbuf_delete(topo);
3192 return (err);
3193}
3194
3195#endif
3196
3197static int
3198sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
3199{
3200 int error, new_val, period;
3201
3202 period = 1000000 / realstathz;
3203 new_val = period * sched_slice;
3204 error = sysctl_handle_int(oidp, &new_val, 0, req);
3205 if (error != 0 || req->newptr == NULL)
3206 return (error);
3207 if (new_val <= 0)
3208 return (EINVAL);
3209 sched_slice = imax(1, (new_val + period / 2) / period);
3210 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR;
3211 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
3212 realstathz);
3213 return (0);
3214}
3215
3216SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
3217 "Scheduler");
3218SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0,
3219 "Scheduler name");
3220SYSCTL_PROC(_kern_sched, OID_AUTO, quantum,
3221 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0,
3222 sysctl_kern_quantum, "I",
3223 "Quantum for timeshare threads in microseconds");
3224SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
3225 "Quantum for timeshare threads in stathz ticks");
3226SYSCTL_UINT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0,
3227 "Interactivity score threshold");
3228SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW,
3229 &preempt_thresh, 0,
3230 "Maximal (lowest) priority for preemption");
3231SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0,
3232 "Assign static kernel priorities to sleeping threads");
3233SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0,
3234 "Number of times idle thread will spin waiting for new work");
3235SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW,
3236 &sched_idlespinthresh, 0,
3237 "Threshold before we will permit idle thread spinning");
3238#ifdef SMP
3239SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0,
3240 "Number of hz ticks to keep thread affinity for");
3241SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0,
3242 "Enables the long-term load balancer");
3243SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW,
3244 &balance_interval, 0,
3245 "Average period in stathz ticks to run the long-term balancer");
3246SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0,
3247 "Attempts to steal work from other cores before idling");
3248SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0,
3249 "Minimum load on remote CPU before we'll steal");
3250SYSCTL_INT(_kern_sched, OID_AUTO, trysteal_limit, CTLFLAG_RW, &trysteal_limit,
3251 0, "Topological distance limit for stealing threads in sched_switch()");
3252SYSCTL_INT(_kern_sched, OID_AUTO, always_steal, CTLFLAG_RW, &always_steal, 0,
3253 "Always run the stealer from the idle thread");
3254SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING |
3255 CTLFLAG_MPSAFE | CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A",
3256 "XML dump of detected CPU topology");
3257#endif
3258
3259/* ps compat. All cpu percentages from ULE are weighted. */
3260static int ccpu = 0;
3261SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0,
3262 "Decay factor used for updating %CPU in 4BSD scheduler");
ts
struct timespec * ts
Definition: clock_if.m:39
parent
device_t parent
Definition: device_if.m:187
name
const char * name
Definition: kern_fail.c:145
bootverbose
int bootverbose
Definition: init_main.c:131
stathz
int stathz
Definition: kern_clock.c:377
ticks
volatile int ticks
Definition: kern_clock.c:380
DPCPU_DEFINE_STATIC
DPCPU_DEFINE_STATIC(int, pcputicks)
cpuset_ref
struct cpuset * cpuset_ref(struct cpuset *set)
Definition: kern_cpuset.c:174
cpusetobj_strprint
char * cpusetobj_strprint(char *buf, const cpuset_t *set)
Definition: kern_cpuset.c:1384
thread_lock_unblock
void thread_lock_unblock(struct thread *td, struct mtx *new)
Definition: kern_mutex.c:975
thread_lock_block_wait
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Definition: kern_mutex.c:986
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Definition: kern_mutex.c:997
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Definition: kern_mutex.c:181
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Definition: kern_mutex.c:963
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Definition: kern_switch.c:369
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Definition: kern_switch.c:180
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Definition: kern_switch.c:518
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Definition: kern_switch.c:266
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Definition: kern_switch.c:473
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Definition: kern_switch.c:388
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Definition: kern_switch.c:525
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Definition: kern_switch.c:493
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Definition: kern_tc.c:2174
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void *** start
Definition: linker_if.m:98
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Definition: msi_if.m:58
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Definition: sched_4bsd.c:163
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Definition: sched_ule.c:2598
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Definition: sched_ule.c:297
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Definition: sched_ule.c:2811
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Definition: sched_ule.c:9
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Definition: sched_ule.c:2907
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Definition: sched_ule.c:133
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Definition: sched_ule.c:2122
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SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW|CTLFLAG_MPSAFE, 0, "Scheduler")
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Definition: sched_ule.c:224
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Definition: sched_ule.c:2419
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Definition: sched_ule.c:213
TDF_SLICEEND
#define TDF_SLICEEND
Definition: sched_ule.c:200
TDQ_CPU
#define TDQ_CPU(x)
Definition: sched_ule.c:298
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Definition: sched_ule.c:3036
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static __inline void tdq_runq_add(struct tdq *, struct thread *, int)
Definition: sched_ule.c:463
__aligned
struct tdq __aligned(64)
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static int __read_mostly sched_idlespinthresh
Definition: sched_ule.c:226
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static void sched_interact_update(struct thread *)
Definition: sched_ule.c:1668
TDF_PICKCPU
#define TDF_PICKCPU
Definition: sched_ule.c:199
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static void sched_interact_fork(struct thread *)
Definition: sched_ule.c:1713
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Definition: sched_ule.c:172
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Definition: sched_ule.c:400
realstathz
static int __read_mostly realstathz
Definition: sched_ule.c:212
SCHED_SLICE_DEFAULT_DIVISOR
#define SCHED_SLICE_DEFAULT_DIVISOR
Definition: sched_ule.c:195
ccpu
static int ccpu
Definition: sched_ule.c:3260
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#define TDQ_UNLOCK(t)
Definition: sched_ule.c:306
TDQ_NAME_LEN
#define TDQ_NAME_LEN
Definition: sched_ule.c:85
sched_unbind
void sched_unbind(struct thread *td)
Definition: sched_ule.c:2835
SCHED_TICK_SECS
#define SCHED_TICK_SECS
Definition: sched_ule.c:145
SYSINIT
SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL)
sched_fork
void sched_fork(struct thread *td, struct thread *child)
Definition: sched_ule.c:2341
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u_int sched_estcpu(struct thread *td __unused)
Definition: sched_ule.c:2562
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static int __read_mostly tickincr
Definition: sched_ule.c:211
TSF_XFERABLE
#define TSF_XFERABLE
Definition: sched_ule.c:109
PRI_MAX_INTERACT
#define PRI_MAX_INTERACT
Definition: sched_ule.c:131
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void sched_fork_thread(struct thread *td, struct thread *child)
Definition: sched_ule.c:2360
SDT_PROBE_DEFINE
SDT_PROBE_DEFINE(sched,,, on__cpu)
SCHED_TICK_MAX
#define SCHED_TICK_MAX
Definition: sched_ule.c:147
SCHED_PRI_RANGE
#define SCHED_PRI_RANGE
Definition: sched_ule.c:168
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static struct thread * sched_throw_grab(struct tdq *tdq)
Definition: sched_ule.c:2994
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#define TDQ_LOCK_FLAGS(t, f)
Definition: sched_ule.c:303
SCHED_PRI_TICKS
#define SCHED_PRI_TICKS(ts)
Definition: sched_ule.c:169
tdq_cpu
static struct tdq tdq_cpu
Definition: sched_ule.c:294
sched_pctcpu_update
static void sched_pctcpu_update(struct td_sched *, int)
Definition: sched_ule.c:1786
sched_unlend_prio
void sched_unlend_prio(struct thread *td, u_char prio)
Definition: sched_ule.c:1884
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static void sched_thread_priority(struct thread *, u_char)
Definition: sched_ule.c:1813
SYSCTL_STRING
SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, "Scheduler name")
tdq_add
static void tdq_add(struct tdq *, struct thread *, int)
Definition: sched_ule.c:2646
_Static_assert
_Static_assert(sizeof(struct thread)+sizeof(struct td_sched)<=sizeof(struct thread0_storage), "increase struct thread0_storage.t0st_sched size")
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void sched_rem(struct thread *td)
Definition: sched_ule.c:2731
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static u_int __read_mostly sched_interact
Definition: sched_ule.c:210
TDQ_TRYLOCK_FLAGS
#define TDQ_TRYLOCK_FLAGS(t, f)
Definition: sched_ule.c:305
THREAD_CAN_SCHED
#define THREAD_CAN_SCHED(td, cpu)
Definition: sched_ule.c:112
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static void sched_priority(struct thread *)
Definition: sched_ule.c:1617
sched_switch_migrate
static struct mtx * sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags)
Definition: sched_ule.c:2090
SCHED_INTERACT_THRESH
#define SCHED_INTERACT_THRESH
Definition: sched_ule.c:190
PRI_BATCH_RANGE
#define PRI_BATCH_RANGE
Definition: sched_ule.c:128
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void sched_class(struct thread *td, int class)
Definition: sched_ule.c:2406
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void sched_prio(struct thread *td, u_char prio)
Definition: sched_ule.c:1904
SCHED_INTERACT_HALF
#define SCHED_INTERACT_HALF
Definition: sched_ule.c:189
SCHED_TICK_HZ
#define SCHED_TICK_HZ(ts)
Definition: sched_ule.c:149
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static int sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
Definition: sched_ule.c:3198
TDQ_LOCK_ASSERT
#define TDQ_LOCK_ASSERT(t, type)
Definition: sched_ule.c:301
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void schedinit_ap(void)
Definition: sched_ule.c:1757
SCHED_TICK_SHIFT
#define SCHED_TICK_SHIFT
Definition: sched_ule.c:148
SYSCTL_PROC
SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_quantum, "I", "Quantum for timeshare threads in microseconds")
SCHED_TICK_TARG
#define SCHED_TICK_TARG
Definition: sched_ule.c:146
TDQ_LOCKPTR
#define TDQ_LOCKPTR(t)
Definition: sched_ule.c:307
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static int __read_mostly sched_slice_min
Definition: sched_ule.c:214
SDT_PROVIDER_DEFINE
SDT_PROVIDER_DEFINE(sched)
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void sched_ap_entry(void)
Definition: sched_ule.c:3010
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void sched_lend_user_prio_cond(struct thread *td, u_char prio)
Definition: sched_ule.c:1960
__FBSDID
__FBSDID("$FreeBSD$")
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void sched_preempt(struct thread *td)
Definition: sched_ule.c:2455
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void sched_clock(struct thread *td, int cnt)
Definition: sched_ule.c:2501
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static void tdq_load_add(struct tdq *, struct thread *)
Definition: sched_ule.c:541
sched_tdname
char * sched_tdname(struct thread *td)
Definition: sched_ule.c:3089
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int sched_sizeof_proc(void)
Definition: sched_ule.c:2885
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static __inline void tdq_runq_rem(struct tdq *, struct thread *)
Definition: sched_ule.c:514
TDQ_LOADNAME_LEN
#define TDQ_LOADNAME_LEN
Definition: sched_ule.c:86
SCHED_PRI_MIN
#define SCHED_PRI_MIN
Definition: sched_ule.c:166
sched_setup
static void sched_setup(void *dummy)
Definition: sched_ule.c:1495
sched_sizeof_thread
int sched_sizeof_thread(void)
Definition: sched_ule.c:2891
SCHED_SLP_RUN_FORK
#define SCHED_SLP_RUN_FORK
Definition: sched_ule.c:187
sched_nice
void sched_nice(struct proc *p, int nice)
Definition: sched_ule.c:2267
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void sched_lend_prio(struct thread *td, u_char prio)
Definition: sched_ule.c:1868
sched_runnable
int sched_runnable(void)
Definition: sched_ule.c:2573
sched_initticks
static void sched_initticks(void *dummy)
Definition: sched_ule.c:1519
sched_affinity
void sched_affinity(struct thread *td)
Definition: sched_ule.c:2780
SCHED_SLP_RUN_MAX
#define SCHED_SLP_RUN_MAX
Definition: sched_ule.c:186
tdq_setup
static void tdq_setup(struct tdq *, int i)
Definition: sched_ule.c:1451
tdq_load
volatile int tdq_load
Definition: sched_ule.c:7
TDQ_ID
#define TDQ_ID(x)
Definition: sched_ule.c:296
SDT_PROBE_DEFINE2
SDT_PROBE_DEFINE2(sched,,, load__change, "int", "int")
TDQ_LOCK
#define TDQ_LOCK(t)
Definition: sched_ule.c:302
sched_load
int sched_load(void)
Definition: sched_ule.c:2869
SDT_PROBE_DEFINE3
SDT_PROBE_DEFINE3(sched,,, change__pri, "struct thread *", "struct proc *", "uint8_t")
sched_fork_exit
void sched_fork_exit(struct thread *td)
Definition: sched_ule.c:3063
SCHED_SLICE_MIN_DIVISOR
#define SCHED_SLICE_MIN_DIVISOR
Definition: sched_ule.c:196
sched_add
void sched_add(struct thread *td, int flags)
Definition: sched_ule.c:2671
SDT_PROBE_DEFINE4
SDT_PROBE_DEFINE4(sched,,, enqueue, "struct thread *", "struct proc *", "void *", "int")
THREAD_CAN_MIGRATE
#define THREAD_CAN_MIGRATE(td)
Definition: sched_ule.c:111
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static struct thread * tdq_choose(struct tdq *)
Definition: sched_ule.c:1421
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void sched_sleep(struct thread *td, int prio)
Definition: sched_ule.c:2286
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static int tdq_slice(struct tdq *tdq)
Definition: sched_ule.c:581
sched_setpreempt
static void sched_setpreempt(struct thread *td)
Definition: sched_ule.c:2620
tdq_load_rem
static void tdq_load_rem(struct tdq *, struct thread *)
Definition: sched_ule.c:559
TSF_BOUND
#define TSF_BOUND
Definition: sched_ule.c:108
tdq_lowpri
u_char tdq_lowpri
Definition: sched_ule.c:13
PRI_MIN_BATCH
#define PRI_MIN_BATCH
Definition: sched_ule.c:132
sched_interact_score
static int sched_interact_score(struct thread *)
Definition: sched_ule.c:1577
TS_NAME_LEN
#define TS_NAME_LEN
Definition: sched_ule.c:84
sched_switch
void sched_switch(struct thread *td, int flags)
Definition: sched_ule.c:2135
SYSCTL_INT
SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, "Quantum for timeshare threads in stathz ticks")
sched_wakeup
void sched_wakeup(struct thread *td, int srqflags)
Definition: sched_ule.c:2309
SYSCTL_UINT
SYSCTL_UINT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, "Interactivity score threshold")
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static void runq_print(struct runq *rq)
Definition: sched_ule.c:372
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static int __read_mostly preempt_thresh
Definition: sched_ule.c:222
sched_is_bound
int sched_is_bound(struct thread *td)
Definition: sched_ule.c:2849
PRI_MIN_INTERACT
#define PRI_MIN_INTERACT
Definition: sched_ule.c:130
sched_user_prio
void sched_user_prio(struct thread *td, u_char prio)
Definition: sched_ule.c:1934
td_sched
Definition: sched_4bsd.c:95
td_sched::ts_runtime
u_int ts_runtime
Definition: sched_ule.c:99
td_sched::ts_slptime
int ts_slptime
Definition: sched_4bsd.c:99
td_sched::ts_flags
int ts_flags
Definition: sched_4bsd.c:101
td_sched::ts_ticks
int ts_ticks
Definition: sched_ule.c:102
td_sched::ts_slice
int ts_slice
Definition: sched_4bsd.c:100
td_sched::ts_flags
short ts_flags
Definition: sched_ule.c:94
td_sched::ts_rltick
int ts_rltick
Definition: sched_ule.c:96
td_sched::ts_runq
struct runq * ts_runq
Definition: sched_4bsd.c:102
td_sched::ts_cpu
int ts_cpu
Definition: sched_ule.c:95
td_sched::ts_slptime
u_int ts_slptime
Definition: sched_ule.c:98
td_sched::ts_ltick
int ts_ltick
Definition: sched_ule.c:100
td_sched::ts_ftick
int ts_ftick
Definition: sched_ule.c:101
tdq
Definition: sched_ule.c:233
tdq::tdq_sysload
int tdq_sysload
Definition: sched_ule.c:243
tdq::tdq_load
volatile int tdq_load
Definition: sched_ule.c:241
tdq::tdq_ridx
u_char tdq_ridx
Definition: sched_ule.c:250
tdq::tdq_idx
u_char tdq_idx
Definition: sched_ule.c:249
tdq::tdq_cpu_idle
volatile int tdq_cpu_idle
Definition: sched_ule.c:242
tdq::tdq_oldswitchcnt
volatile short tdq_oldswitchcnt
Definition: sched_ule.c:246
tdq::tdq_realtime
struct runq tdq_realtime
Definition: sched_ule.c:252
tdq::tdq_timeshare
struct runq tdq_timeshare
Definition: sched_ule.c:253
tdq::tdq_transferable
volatile int tdq_transferable
Definition: sched_ule.c:244
tdq::tdq_lock
struct mtx_padalign tdq_lock
Definition: sched_ule.c:239
tdq::tdq_switchcnt
volatile short tdq_switchcnt
Definition: sched_ule.c:245
tdq::tdq_lowpri
u_char tdq_lowpri
Definition: sched_ule.c:247
tdq::tdq_id
int tdq_id
Definition: sched_ule.c:251
tdq::tdq_name
char tdq_name[TDQ_NAME_LEN]
Definition: sched_ule.c:255
tdq::tdq_owepreempt
u_char tdq_owepreempt
Definition: sched_ule.c:248
tdq::tdq_idle
struct runq tdq_idle
Definition: sched_ule.c:254
tdq::tdq_cg
struct cpu_group * tdq_cg
Definition: sched_ule.c:240
mask
int mask
Definition: subr_acl_nfs4.c:70
__read_mostly
static bool kasan_enabled __read_mostly
Definition: subr_asan.c:95
hz
int hz
Definition: subr_param.c:85
pcpu_find
struct pcpu * pcpu_find(u_int cpuid)
Definition: subr_pcpu.c:283
printf
int printf(const char *fmt,...)
Definition: subr_prf.c:397
snprintf
int snprintf(char *str, size_t size, const char *format,...)
Definition: subr_prf.c:550
sbuf_finish
int sbuf_finish(struct sbuf *s)
Definition: subr_sbuf.c:833
sbuf_delete
void sbuf_delete(struct sbuf *s)
Definition: subr_sbuf.c:898
sbuf_printf
int sbuf_printf(struct sbuf *s, const char *fmt,...)
Definition: subr_sbuf.c:739
smp_started
volatile int smp_started
Definition: subr_smp.c:76
flags
uint16_t flags
Definition: subr_stats.c:2
turnstile_adjust
void turnstile_adjust(struct thread *td, u_char oldpri)
Definition: subr_turnstile.c:444
mtx
struct mtx mtx
Definition: uipc_ktls.c:0
dummy
static int dummy
Definition: uipc_sockbuf.c:1785