FreeBSD kernel kern code
sched_ule.c
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1 /*-
2  * Copyright (c) 2002-2007, Jeffrey Roberson <jeff@freebsd.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  * notice unmodified, this list of conditions, and the following
10  * disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  * notice, this list of conditions and the following disclaimer in the
13  * documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 
27 /*
28  * This file implements the ULE scheduler. ULE supports independent CPU
29  * run queues and fine grain locking. It has superior interactive
30  * performance under load even on uni-processor systems.
31  *
32  * etymology:
33  * ULE is the last three letters in schedule. It owes its name to a
34  * generic user created for a scheduling system by Paul Mikesell at
35  * Isilon Systems and a general lack of creativity on the part of the author.
36  */
37 
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD: head/sys/kern/sched_ule.c 270423 2014-08-23 17:31:56Z mav $");
40 
41 #include "opt_hwpmc_hooks.h"
42 #include "opt_sched.h"
43 
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/kdb.h>
47 #include <sys/kernel.h>
48 #include <sys/ktr.h>
49 #include <sys/limits.h>
50 #include <sys/lock.h>
51 #include <sys/mutex.h>
52 #include <sys/proc.h>
53 #include <sys/resource.h>
54 #include <sys/resourcevar.h>
55 #include <sys/sched.h>
56 #include <sys/sdt.h>
57 #include <sys/smp.h>
58 #include <sys/sx.h>
59 #include <sys/sysctl.h>
60 #include <sys/sysproto.h>
61 #include <sys/turnstile.h>
62 #include <sys/umtx.h>
63 #include <sys/vmmeter.h>
64 #include <sys/cpuset.h>
65 #include <sys/sbuf.h>
66 
67 #ifdef HWPMC_HOOKS
68 #include <sys/pmckern.h>
69 #endif
70 
71 #ifdef KDTRACE_HOOKS
72 #include <sys/dtrace_bsd.h>
73 int dtrace_vtime_active;
74 dtrace_vtime_switch_func_t dtrace_vtime_switch_func;
75 #endif
76 
77 #include <machine/cpu.h>
78 #include <machine/smp.h>
79 
80 #define KTR_ULE 0
81 
82 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX)))
83 #define TDQ_NAME_LEN (sizeof("sched lock ") + sizeof(__XSTRING(MAXCPU)))
84 #define TDQ_LOADNAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1 + sizeof(" load"))
85 
86 /*
87  * Thread scheduler specific section. All fields are protected
88  * by the thread lock.
89  */
90 struct td_sched {
91  struct runq *ts_runq; /* Run-queue we're queued on. */
92  short ts_flags; /* TSF_* flags. */
93  u_char ts_cpu; /* CPU that we have affinity for. */
94  int ts_rltick; /* Real last tick, for affinity. */
95  int ts_slice; /* Ticks of slice remaining. */
96  u_int ts_slptime; /* Number of ticks we vol. slept */
97  u_int ts_runtime; /* Number of ticks we were running */
98  int ts_ltick; /* Last tick that we were running on */
99  int ts_ftick; /* First tick that we were running on */
100  int ts_ticks; /* Tick count */
101 #ifdef KTR
102  char ts_name[TS_NAME_LEN];
103 #endif
104 };
105 /* flags kept in ts_flags */
106 #define TSF_BOUND 0x0001 /* Thread can not migrate. */
107 #define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */
108 
109 static struct td_sched td_sched0;
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 /*
116  * Priority ranges used for interactive and non-interactive timeshare
117  * threads. The timeshare priorities are split up into four ranges.
118  * The first range handles interactive threads. The last three ranges
119  * (NHALF, x, and NHALF) handle non-interactive threads with the outer
120  * ranges supporting nice values.
121  */
122 #define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1)
123 #define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2)
124 #define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE)
125 
126 #define PRI_MIN_INTERACT PRI_MIN_TIMESHARE
127 #define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1)
128 #define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE)
129 #define PRI_MAX_BATCH PRI_MAX_TIMESHARE
130 
131 /*
132  * Cpu percentage computation macros and defines.
133  *
134  * SCHED_TICK_SECS: Number of seconds to average the cpu usage across.
135  * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across.
136  * SCHED_TICK_MAX: Maximum number of ticks before scaling back.
137  * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results.
138  * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count.
139  * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks.
140  */
141 #define SCHED_TICK_SECS 10
142 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS)
143 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz)
144 #define SCHED_TICK_SHIFT 10
145 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT)
146 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz))
147 
148 /*
149  * These macros determine priorities for non-interactive threads. They are
150  * assigned a priority based on their recent cpu utilization as expressed
151  * by the ratio of ticks to the tick total. NHALF priorities at the start
152  * and end of the MIN to MAX timeshare range are only reachable with negative
153  * or positive nice respectively.
154  *
155  * PRI_RANGE: Priority range for utilization dependent priorities.
156  * PRI_NRESV: Number of nice values.
157  * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total.
158  * PRI_NICE: Determines the part of the priority inherited from nice.
159  */
160 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN)
161 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2)
162 #define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF)
163 #define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF)
164 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1)
165 #define SCHED_PRI_TICKS(ts) \
166  (SCHED_TICK_HZ((ts)) / \
167  (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE))
168 #define SCHED_PRI_NICE(nice) (nice)
169 
170 /*
171  * These determine the interactivity of a process. Interactivity differs from
172  * cpu utilization in that it expresses the voluntary time slept vs time ran
173  * while cpu utilization includes all time not running. This more accurately
174  * models the intent of the thread.
175  *
176  * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate
177  * before throttling back.
178  * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time.
179  * INTERACT_MAX: Maximum interactivity value. Smaller is better.
180  * INTERACT_THRESH: Threshold for placement on the current runq.
181  */
182 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT)
183 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT)
184 #define SCHED_INTERACT_MAX (100)
185 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2)
186 #define SCHED_INTERACT_THRESH (30)
187 
188 /*
189  * These parameters determine the slice behavior for batch work.
190  */
191 #define SCHED_SLICE_DEFAULT_DIVISOR 10 /* ~94 ms, 12 stathz ticks. */
192 #define SCHED_SLICE_MIN_DIVISOR 6 /* DEFAULT/MIN = ~16 ms. */
193 
194 /* Flags kept in td_flags. */
195 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */
196 
197 /*
198  * tickincr: Converts a stathz tick into a hz domain scaled by
199  * the shift factor. Without the shift the error rate
200  * due to rounding would be unacceptably high.
201  * realstathz: stathz is sometimes 0 and run off of hz.
202  * sched_slice: Runtime of each thread before rescheduling.
203  * preempt_thresh: Priority threshold for preemption and remote IPIs.
204  */
206 static int tickincr = 8 << SCHED_TICK_SHIFT;
207 static int realstathz = 127; /* reset during boot. */
208 static int sched_slice = 10; /* reset during boot. */
209 static int sched_slice_min = 1; /* reset during boot. */
210 #ifdef PREEMPTION
211 #ifdef FULL_PREEMPTION
212 static int preempt_thresh = PRI_MAX_IDLE;
213 #else
214 static int preempt_thresh = PRI_MIN_KERN;
215 #endif
216 #else
217 static int preempt_thresh = 0;
218 #endif
220 static int sched_idlespins = 10000;
221 static int sched_idlespinthresh = -1;
222 
223 /*
224  * tdq - per processor runqs and statistics. All fields are protected by the
225  * tdq_lock. The load and lowpri may be accessed without to avoid excess
226  * locking in sched_pickcpu();
227  */
228 struct tdq {
229  /*
230  * Ordered to improve efficiency of cpu_search() and switch().
231  * tdq_lock is padded to avoid false sharing with tdq_load and
232  * tdq_cpu_idle.
233  */
234  struct mtx_padalign tdq_lock; /* run queue lock. */
235  struct cpu_group *tdq_cg; /* Pointer to cpu topology. */
236  volatile int tdq_load; /* Aggregate load. */
237  volatile int tdq_cpu_idle; /* cpu_idle() is active. */
238  int tdq_sysload; /* For loadavg, !ITHD load. */
239  int tdq_transferable; /* Transferable thread count. */
240  short tdq_switchcnt; /* Switches this tick. */
241  short tdq_oldswitchcnt; /* Switches last tick. */
242  u_char tdq_lowpri; /* Lowest priority thread. */
243  u_char tdq_ipipending; /* IPI pending. */
244  u_char tdq_idx; /* Current insert index. */
245  u_char tdq_ridx; /* Current removal index. */
246  struct runq tdq_realtime; /* real-time run queue. */
247  struct runq tdq_timeshare; /* timeshare run queue. */
248  struct runq tdq_idle; /* Queue of IDLE threads. */
250 #ifdef KTR
251  char tdq_loadname[TDQ_LOADNAME_LEN];
252 #endif
253 } __aligned(64);
254 
255 /* Idle thread states and config. */
256 #define TDQ_RUNNING 1
257 #define TDQ_IDLE 2
258 
259 #ifdef SMP
260 struct cpu_group *cpu_top; /* CPU topology */
262 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000))
263 #define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity))
265 /*
266  * Run-time tunables.
267  */
268 static int rebalance = 1;
269 static int balance_interval = 128; /* Default set in sched_initticks(). */
270 static int affinity;
271 static int steal_idle = 1;
272 static int steal_thresh = 2;
274 /*
275  * One thread queue per processor.
276  */
277 static struct tdq tdq_cpu[MAXCPU];
278 static struct tdq *balance_tdq;
279 static int balance_ticks;
280 static DPCPU_DEFINE(uint32_t, randomval);
281 
282 #define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)])
283 #define TDQ_CPU(x) (&tdq_cpu[(x)])
284 #define TDQ_ID(x) ((int)((x) - tdq_cpu))
285 #else /* !SMP */
286 static struct tdq tdq_cpu;
287 
288 #define TDQ_ID(x) (0)
289 #define TDQ_SELF() (&tdq_cpu)
290 #define TDQ_CPU(x) (&tdq_cpu)
291 #endif
292 
293 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type))
294 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t)))
295 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f))
296 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t)))
297 #define TDQ_LOCKPTR(t) ((struct mtx *)(&(t)->tdq_lock))
298 
299 static void sched_priority(struct thread *);
300 static void sched_thread_priority(struct thread *, u_char);
301 static int sched_interact_score(struct thread *);
302 static void sched_interact_update(struct thread *);
303 static void sched_interact_fork(struct thread *);
304 static void sched_pctcpu_update(struct td_sched *, int);
305 
306 /* Operations on per processor queues */
307 static struct thread *tdq_choose(struct tdq *);
308 static void tdq_setup(struct tdq *);
309 static void tdq_load_add(struct tdq *, struct thread *);
310 static void tdq_load_rem(struct tdq *, struct thread *);
311 static __inline void tdq_runq_add(struct tdq *, struct thread *, int);
312 static __inline void tdq_runq_rem(struct tdq *, struct thread *);
313 static inline int sched_shouldpreempt(int, int, int);
314 void tdq_print(int cpu);
315 static void runq_print(struct runq *rq);
316 static void tdq_add(struct tdq *, struct thread *, int);
317 #ifdef SMP
318 static int tdq_move(struct tdq *, struct tdq *);
319 static int tdq_idled(struct tdq *);
320 static void tdq_notify(struct tdq *, struct thread *);
321 static struct thread *tdq_steal(struct tdq *, int);
322 static struct thread *runq_steal(struct runq *, int);
323 static int sched_pickcpu(struct thread *, int);
324 static void sched_balance(void);
325 static int sched_balance_pair(struct tdq *, struct tdq *);
326 static inline struct tdq *sched_setcpu(struct thread *, int, int);
327 static inline void thread_unblock_switch(struct thread *, struct mtx *);
328 static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int);
329 static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS);
330 static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb,
331  struct cpu_group *cg, int indent);
332 #endif
333 
334 static void sched_setup(void *dummy);
335 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL);
336 
337 static void sched_initticks(void *dummy);
338 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks,
339  NULL);
340 
341 SDT_PROVIDER_DEFINE(sched);
342 
343 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *",
344  "struct proc *", "uint8_t");
345 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *",
346  "struct proc *", "void *");
347 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *",
348  "struct proc *", "void *", "int");
349 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *",
350  "struct proc *", "uint8_t", "struct thread *");
351 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int");
352 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *",
353  "struct proc *");
354 SDT_PROBE_DEFINE(sched, , , on__cpu);
355 SDT_PROBE_DEFINE(sched, , , remain__cpu);
356 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *",
357  "struct proc *");
358 
359 /*
360  * Print the threads waiting on a run-queue.
361  */
362 static void
363 runq_print(struct runq *rq)
364 {
365  struct rqhead *rqh;
366  struct thread *td;
367  int pri;
368  int j;
369  int i;
370 
371  for (i = 0; i < RQB_LEN; i++) {
372  printf("\t\trunq bits %d 0x%zx\n",
373  i, rq->rq_status.rqb_bits[i]);
374  for (j = 0; j < RQB_BPW; j++)
375  if (rq->rq_status.rqb_bits[i] & (1ul << j)) {
376  pri = j + (i << RQB_L2BPW);
377  rqh = &rq->rq_queues[pri];
378  TAILQ_FOREACH(td, rqh, td_runq) {
379  printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n",
380  td, td->td_name, td->td_priority,
381  td->td_rqindex, pri);
382  }
383  }
384  }
385 }
386 
387 /*
388  * Print the status of a per-cpu thread queue. Should be a ddb show cmd.
389  */
390 void
391 tdq_print(int cpu)
392 {
393  struct tdq *tdq;
394 
395  tdq = TDQ_CPU(cpu);
396 
397  printf("tdq %d:\n", TDQ_ID(tdq));
398  printf("\tlock %p\n", TDQ_LOCKPTR(tdq));
399  printf("\tLock name: %s\n", tdq->tdq_name);
400  printf("\tload: %d\n", tdq->tdq_load);
401  printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt);
402  printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt);
403  printf("\ttimeshare idx: %d\n", tdq->tdq_idx);
404  printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx);
405  printf("\tload transferable: %d\n", tdq->tdq_transferable);
406  printf("\tlowest priority: %d\n", tdq->tdq_lowpri);
407  printf("\trealtime runq:\n");
408  runq_print(&tdq->tdq_realtime);
409  printf("\ttimeshare runq:\n");
410  runq_print(&tdq->tdq_timeshare);
411  printf("\tidle runq:\n");
412  runq_print(&tdq->tdq_idle);
413 }
414 
415 static inline int
416 sched_shouldpreempt(int pri, int cpri, int remote)
417 {
418  /*
419  * If the new priority is not better than the current priority there is
420  * nothing to do.
421  */
422  if (pri >= cpri)
423  return (0);
424  /*
425  * Always preempt idle.
426  */
427  if (cpri >= PRI_MIN_IDLE)
428  return (1);
429  /*
430  * If preemption is disabled don't preempt others.
431  */
432  if (preempt_thresh == 0)
433  return (0);
434  /*
435  * Preempt if we exceed the threshold.
436  */
437  if (pri <= preempt_thresh)
438  return (1);
439  /*
440  * If we're interactive or better and there is non-interactive
441  * or worse running preempt only remote processors.
442  */
443  if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT)
444  return (1);
445  return (0);
446 }
447 
448 /*
449  * Add a thread to the actual run-queue. Keeps transferable counts up to
450  * date with what is actually on the run-queue. Selects the correct
451  * queue position for timeshare threads.
452  */
453 static __inline void
454 tdq_runq_add(struct tdq *tdq, struct thread *td, int flags)
455 {
456  struct td_sched *ts;
457  u_char pri;
458 
459  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
460  THREAD_LOCK_ASSERT(td, MA_OWNED);
461 
462  pri = td->td_priority;
463  ts = td->td_sched;
464  TD_SET_RUNQ(td);
465  if (THREAD_CAN_MIGRATE(td)) {
466  tdq->tdq_transferable++;
467  ts->ts_flags |= TSF_XFERABLE;
468  }
469  if (pri < PRI_MIN_BATCH) {
470  ts->ts_runq = &tdq->tdq_realtime;
471  } else if (pri <= PRI_MAX_BATCH) {
472  ts->ts_runq = &tdq->tdq_timeshare;
473  KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH,
474  ("Invalid priority %d on timeshare runq", pri));
475  /*
476  * This queue contains only priorities between MIN and MAX
477  * realtime. Use the whole queue to represent these values.
478  */
479  if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) {
480  pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE;
481  pri = (pri + tdq->tdq_idx) % RQ_NQS;
482  /*
483  * This effectively shortens the queue by one so we
484  * can have a one slot difference between idx and
485  * ridx while we wait for threads to drain.
486  */
487  if (tdq->tdq_ridx != tdq->tdq_idx &&
488  pri == tdq->tdq_ridx)
489  pri = (unsigned char)(pri - 1) % RQ_NQS;
490  } else
491  pri = tdq->tdq_ridx;
492  runq_add_pri(ts->ts_runq, td, pri, flags);
493  return;
494  } else
495  ts->ts_runq = &tdq->tdq_idle;
496  runq_add(ts->ts_runq, td, flags);
497 }
498 
499 /*
500  * Remove a thread from a run-queue. This typically happens when a thread
501  * is selected to run. Running threads are not on the queue and the
502  * transferable count does not reflect them.
503  */
504 static __inline void
505 tdq_runq_rem(struct tdq *tdq, struct thread *td)
506 {
507  struct td_sched *ts;
508 
509  ts = td->td_sched;
510  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
511  KASSERT(ts->ts_runq != NULL,
512  ("tdq_runq_remove: thread %p null ts_runq", td));
513  if (ts->ts_flags & TSF_XFERABLE) {
514  tdq->tdq_transferable--;
515  ts->ts_flags &= ~TSF_XFERABLE;
516  }
517  if (ts->ts_runq == &tdq->tdq_timeshare) {
518  if (tdq->tdq_idx != tdq->tdq_ridx)
519  runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx);
520  else
521  runq_remove_idx(ts->ts_runq, td, NULL);
522  } else
523  runq_remove(ts->ts_runq, td);
524 }
525 
526 /*
527  * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load
528  * for this thread to the referenced thread queue.
529  */
530 static void
531 tdq_load_add(struct tdq *tdq, struct thread *td)
532 {
533 
534  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
535  THREAD_LOCK_ASSERT(td, MA_OWNED);
536 
537  tdq->tdq_load++;
538  if ((td->td_flags & TDF_NOLOAD) == 0)
539  tdq->tdq_sysload++;
540  KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load);
541  SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load);
542 }
543 
544 /*
545  * Remove the load from a thread that is transitioning to a sleep state or
546  * exiting.
547  */
548 static void
549 tdq_load_rem(struct tdq *tdq, struct thread *td)
550 {
551 
552  THREAD_LOCK_ASSERT(td, MA_OWNED);
553  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
554  KASSERT(tdq->tdq_load != 0,
555  ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq)));
556 
557  tdq->tdq_load--;
558  if ((td->td_flags & TDF_NOLOAD) == 0)
559  tdq->tdq_sysload--;
560  KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load);
561  SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load);
562 }
563 
564 /*
565  * Bound timeshare latency by decreasing slice size as load increases. We
566  * consider the maximum latency as the sum of the threads waiting to run
567  * aside from curthread and target no more than sched_slice latency but
568  * no less than sched_slice_min runtime.
569  */
570 static inline int
571 tdq_slice(struct tdq *tdq)
572 {
573  int load;
574 
575  /*
576  * It is safe to use sys_load here because this is called from
577  * contexts where timeshare threads are running and so there
578  * cannot be higher priority load in the system.
579  */
580  load = tdq->tdq_sysload - 1;
581  if (load >= SCHED_SLICE_MIN_DIVISOR)
582  return (sched_slice_min);
583  if (load <= 1)
584  return (sched_slice);
585  return (sched_slice / load);
586 }
587 
588 /*
589  * Set lowpri to its exact value by searching the run-queue and
590  * evaluating curthread. curthread may be passed as an optimization.
591  */
592 static void
593 tdq_setlowpri(struct tdq *tdq, struct thread *ctd)
594 {
595  struct thread *td;
596 
597  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
598  if (ctd == NULL)
599  ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread;
600  td = tdq_choose(tdq);
601  if (td == NULL || td->td_priority > ctd->td_priority)
602  tdq->tdq_lowpri = ctd->td_priority;
603  else
604  tdq->tdq_lowpri = td->td_priority;
605 }
606 
607 #ifdef SMP
608 struct cpu_search {
609  cpuset_t cs_mask;
610  u_int cs_prefer;
611  int cs_pri; /* Min priority for low. */
612  int cs_limit; /* Max load for low, min load for high. */
613  int cs_cpu;
614  int cs_load;
615 };
616 
617 #define CPU_SEARCH_LOWEST 0x1
618 #define CPU_SEARCH_HIGHEST 0x2
619 #define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST)
620 
621 #define CPUSET_FOREACH(cpu, mask) \
622  for ((cpu) = 0; (cpu) <= mp_maxid; (cpu)++) \
623  if (CPU_ISSET(cpu, &mask))
624 
625 static __always_inline int cpu_search(const struct cpu_group *cg,
626  struct cpu_search *low, struct cpu_search *high, const int match);
627 int __noinline cpu_search_lowest(const struct cpu_group *cg,
628  struct cpu_search *low);
629 int __noinline cpu_search_highest(const struct cpu_group *cg,
630  struct cpu_search *high);
631 int __noinline cpu_search_both(const struct cpu_group *cg,
632  struct cpu_search *low, struct cpu_search *high);
633 
634 /*
635  * Search the tree of cpu_groups for the lowest or highest loaded cpu
636  * according to the match argument. This routine actually compares the
637  * load on all paths through the tree and finds the least loaded cpu on
638  * the least loaded path, which may differ from the least loaded cpu in
639  * the system. This balances work among caches and busses.
640  *
641  * This inline is instantiated in three forms below using constants for the
642  * match argument. It is reduced to the minimum set for each case. It is
643  * also recursive to the depth of the tree.
644  */
645 static __always_inline int
646 cpu_search(const struct cpu_group *cg, struct cpu_search *low,
647  struct cpu_search *high, const int match)
648 {
649  struct cpu_search lgroup;
650  struct cpu_search hgroup;
651  cpuset_t cpumask;
652  struct cpu_group *child;
653  struct tdq *tdq;
654  int cpu, i, hload, lload, load, total, rnd, *rndptr;
655 
656  total = 0;
657  cpumask = cg->cg_mask;
658  if (match & CPU_SEARCH_LOWEST) {
659  lload = INT_MAX;
660  lgroup = *low;
661  }
662  if (match & CPU_SEARCH_HIGHEST) {
663  hload = INT_MIN;
664  hgroup = *high;
665  }
666 
667  /* Iterate through the child CPU groups and then remaining CPUs. */
668  for (i = cg->cg_children, cpu = mp_maxid; ; ) {
669  if (i == 0) {
670 #ifdef HAVE_INLINE_FFSL
671  cpu = CPU_FFS(&cpumask) - 1;
672 #else
673  while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask))
674  cpu--;
675 #endif
676  if (cpu < 0)
677  break;
678  child = NULL;
679  } else
680  child = &cg->cg_child[i - 1];
681 
682  if (match & CPU_SEARCH_LOWEST)
683  lgroup.cs_cpu = -1;
684  if (match & CPU_SEARCH_HIGHEST)
685  hgroup.cs_cpu = -1;
686  if (child) { /* Handle child CPU group. */
687  CPU_NAND(&cpumask, &child->cg_mask);
688  switch (match) {
689  case CPU_SEARCH_LOWEST:
690  load = cpu_search_lowest(child, &lgroup);
691  break;
692  case CPU_SEARCH_HIGHEST:
693  load = cpu_search_highest(child, &hgroup);
694  break;
695  case CPU_SEARCH_BOTH:
696  load = cpu_search_both(child, &lgroup, &hgroup);
697  break;
698  }
699  } else { /* Handle child CPU. */
700  CPU_CLR(cpu, &cpumask);
701  tdq = TDQ_CPU(cpu);
702  load = tdq->tdq_load * 256;
703  rndptr = DPCPU_PTR(randomval);
704  rnd = (*rndptr = *rndptr * 69069 + 5) >> 26;
705  if (match & CPU_SEARCH_LOWEST) {
706  if (cpu == low->cs_prefer)
707  load -= 64;
708  /* If that CPU is allowed and get data. */
709  if (tdq->tdq_lowpri > lgroup.cs_pri &&
710  tdq->tdq_load <= lgroup.cs_limit &&
711  CPU_ISSET(cpu, &lgroup.cs_mask)) {
712  lgroup.cs_cpu = cpu;
713  lgroup.cs_load = load - rnd;
714  }
715  }
716  if (match & CPU_SEARCH_HIGHEST)
717  if (tdq->tdq_load >= hgroup.cs_limit &&
718  tdq->tdq_transferable &&
719  CPU_ISSET(cpu, &hgroup.cs_mask)) {
720  hgroup.cs_cpu = cpu;
721  hgroup.cs_load = load - rnd;
722  }
723  }
724  total += load;
725 
726  /* We have info about child item. Compare it. */
727  if (match & CPU_SEARCH_LOWEST) {
728  if (lgroup.cs_cpu >= 0 &&
729  (load < lload ||
730  (load == lload && lgroup.cs_load < low->cs_load))) {
731  lload = load;
732  low->cs_cpu = lgroup.cs_cpu;
733  low->cs_load = lgroup.cs_load;
734  }
735  }
736  if (match & CPU_SEARCH_HIGHEST)
737  if (hgroup.cs_cpu >= 0 &&
738  (load > hload ||
739  (load == hload && hgroup.cs_load > high->cs_load))) {
740  hload = load;
741  high->cs_cpu = hgroup.cs_cpu;
742  high->cs_load = hgroup.cs_load;
743  }
744  if (child) {
745  i--;
746  if (i == 0 && CPU_EMPTY(&cpumask))
747  break;
748  }
749 #ifndef HAVE_INLINE_FFSL
750  else
751  cpu--;
752 #endif
753  }
754  return (total);
755 }
756 
757 /*
758  * cpu_search instantiations must pass constants to maintain the inline
759  * optimization.
760  */
761 int
762 cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low)
763 {
764  return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST);
765 }
766 
767 int
768 cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high)
769 {
770  return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST);
771 }
772 
773 int
774 cpu_search_both(const struct cpu_group *cg, struct cpu_search *low,
775  struct cpu_search *high)
776 {
777  return cpu_search(cg, low, high, CPU_SEARCH_BOTH);
778 }
779 
780 /*
781  * Find the cpu with the least load via the least loaded path that has a
782  * lowpri greater than pri pri. A pri of -1 indicates any priority is
783  * acceptable.
784  */
785 static inline int
786 sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload,
787  int prefer)
788 {
789  struct cpu_search low;
790 
791  low.cs_cpu = -1;
792  low.cs_prefer = prefer;
793  low.cs_mask = mask;
794  low.cs_pri = pri;
795  low.cs_limit = maxload;
796  cpu_search_lowest(cg, &low);
797  return low.cs_cpu;
798 }
799 
800 /*
801  * Find the cpu with the highest load via the highest loaded path.
802  */
803 static inline int
804 sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload)
805 {
806  struct cpu_search high;
807 
808  high.cs_cpu = -1;
809  high.cs_mask = mask;
810  high.cs_limit = minload;
811  cpu_search_highest(cg, &high);
812  return high.cs_cpu;
813 }
814 
815 static void
816 sched_balance_group(struct cpu_group *cg)
817 {
818  cpuset_t hmask, lmask;
819  int high, low, anylow;
820 
821  CPU_FILL(&hmask);
822  for (;;) {
823  high = sched_highest(cg, hmask, 1);
824  /* Stop if there is no more CPU with transferrable threads. */
825  if (high == -1)
826  break;
827  CPU_CLR(high, &hmask);
828  CPU_COPY(&hmask, &lmask);
829  /* Stop if there is no more CPU left for low. */
830  if (CPU_EMPTY(&lmask))
831  break;
832  anylow = 1;
833 nextlow:
834  low = sched_lowest(cg, lmask, -1,
835  TDQ_CPU(high)->tdq_load - 1, high);
836  /* Stop if we looked well and found no less loaded CPU. */
837  if (anylow && low == -1)
838  break;
839  /* Go to next high if we found no less loaded CPU. */
840  if (low == -1)
841  continue;
842  /* Transfer thread from high to low. */
843  if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) {
844  /* CPU that got thread can no longer be a donor. */
845  CPU_CLR(low, &hmask);
846  } else {
847  /*
848  * If failed, then there is no threads on high
849  * that can run on this low. Drop low from low
850  * mask and look for different one.
851  */
852  CPU_CLR(low, &lmask);
853  anylow = 0;
854  goto nextlow;
855  }
856  }
857 }
858 
859 static void
860 sched_balance(void)
861 {
862  struct tdq *tdq;
863 
864  /*
865  * Select a random time between .5 * balance_interval and
866  * 1.5 * balance_interval.
867  */
868  balance_ticks = max(balance_interval / 2, 1);
869  balance_ticks += random() % balance_interval;
870  if (smp_started == 0 || rebalance == 0)
871  return;
872  tdq = TDQ_SELF();
873  TDQ_UNLOCK(tdq);
874  sched_balance_group(cpu_top);
875  TDQ_LOCK(tdq);
876 }
877 
878 /*
879  * Lock two thread queues using their address to maintain lock order.
880  */
881 static void
882 tdq_lock_pair(struct tdq *one, struct tdq *two)
883 {
884  if (one < two) {
885  TDQ_LOCK(one);
886  TDQ_LOCK_FLAGS(two, MTX_DUPOK);
887  } else {
888  TDQ_LOCK(two);
889  TDQ_LOCK_FLAGS(one, MTX_DUPOK);
890  }
891 }
892 
893 /*
894  * Unlock two thread queues. Order is not important here.
895  */
896 static void
897 tdq_unlock_pair(struct tdq *one, struct tdq *two)
898 {
899  TDQ_UNLOCK(one);
900  TDQ_UNLOCK(two);
901 }
902 
903 /*
904  * Transfer load between two imbalanced thread queues.
905  */
906 static int
907 sched_balance_pair(struct tdq *high, struct tdq *low)
908 {
909  int moved;
910  int cpu;
911 
912  tdq_lock_pair(high, low);
913  moved = 0;
914  /*
915  * Determine what the imbalance is and then adjust that to how many
916  * threads we actually have to give up (transferable).
917  */
918  if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load &&
919  (moved = tdq_move(high, low)) > 0) {
920  /*
921  * In case the target isn't the current cpu IPI it to force a
922  * reschedule with the new workload.
923  */
924  cpu = TDQ_ID(low);
925  if (cpu != PCPU_GET(cpuid))
926  ipi_cpu(cpu, IPI_PREEMPT);
927  }
928  tdq_unlock_pair(high, low);
929  return (moved);
930 }
931 
932 /*
933  * Move a thread from one thread queue to another.
934  */
935 static int
936 tdq_move(struct tdq *from, struct tdq *to)
937 {
938  struct td_sched *ts;
939  struct thread *td;
940  struct tdq *tdq;
941  int cpu;
942 
943  TDQ_LOCK_ASSERT(from, MA_OWNED);
944  TDQ_LOCK_ASSERT(to, MA_OWNED);
945 
946  tdq = from;
947  cpu = TDQ_ID(to);
948  td = tdq_steal(tdq, cpu);
949  if (td == NULL)
950  return (0);
951  ts = td->td_sched;
952  /*
953  * Although the run queue is locked the thread may be blocked. Lock
954  * it to clear this and acquire the run-queue lock.
955  */
956  thread_lock(td);
957  /* Drop recursive lock on from acquired via thread_lock(). */
958  TDQ_UNLOCK(from);
959  sched_rem(td);
960  ts->ts_cpu = cpu;
961  td->td_lock = TDQ_LOCKPTR(to);
962  tdq_add(to, td, SRQ_YIELDING);
963  return (1);
964 }
965 
966 /*
967  * This tdq has idled. Try to steal a thread from another cpu and switch
968  * to it.
969  */
970 static int
971 tdq_idled(struct tdq *tdq)
972 {
973  struct cpu_group *cg;
974  struct tdq *steal;
975  cpuset_t mask;
976  int thresh;
977  int cpu;
978 
979  if (smp_started == 0 || steal_idle == 0)
980  return (1);
981  CPU_FILL(&mask);
982  CPU_CLR(PCPU_GET(cpuid), &mask);
983  /* We don't want to be preempted while we're iterating. */
984  spinlock_enter();
985  for (cg = tdq->tdq_cg; cg != NULL; ) {
986  if ((cg->cg_flags & CG_FLAG_THREAD) == 0)
987  thresh = steal_thresh;
988  else
989  thresh = 1;
990  cpu = sched_highest(cg, mask, thresh);
991  if (cpu == -1) {
992  cg = cg->cg_parent;
993  continue;
994  }
995  steal = TDQ_CPU(cpu);
996  CPU_CLR(cpu, &mask);
997  tdq_lock_pair(tdq, steal);
998  if (steal->tdq_load < thresh || steal->tdq_transferable == 0) {
999  tdq_unlock_pair(tdq, steal);
1000  continue;
1001  }
1002  /*
1003  * If a thread was added while interrupts were disabled don't
1004  * steal one here. If we fail to acquire one due to affinity
1005  * restrictions loop again with this cpu removed from the
1006  * set.
1007  */
1008  if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) {
1009  tdq_unlock_pair(tdq, steal);
1010  continue;
1011  }
1012  spinlock_exit();
1013  TDQ_UNLOCK(steal);
1014  mi_switch(SW_VOL | SWT_IDLE, NULL);
1015  thread_unlock(curthread);
1016 
1017  return (0);
1018  }
1019  spinlock_exit();
1020  return (1);
1021 }
1022 
1023 /*
1024  * Notify a remote cpu of new work. Sends an IPI if criteria are met.
1025  */
1026 static void
1027 tdq_notify(struct tdq *tdq, struct thread *td)
1028 {
1029  struct thread *ctd;
1030  int pri;
1031  int cpu;
1032 
1033  if (tdq->tdq_ipipending)
1034  return;
1035  cpu = td->td_sched->ts_cpu;
1036  pri = td->td_priority;
1037  ctd = pcpu_find(cpu)->pc_curthread;
1038  if (!sched_shouldpreempt(pri, ctd->td_priority, 1))
1039  return;
1040  if (TD_IS_IDLETHREAD(ctd)) {
1041  /*
1042  * If the MD code has an idle wakeup routine try that before
1043  * falling back to IPI.
1044  */
1045  if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu))
1046  return;
1047  }
1048  tdq->tdq_ipipending = 1;
1049  ipi_cpu(cpu, IPI_PREEMPT);
1050 }
1051 
1052 /*
1053  * Steals load from a timeshare queue. Honors the rotating queue head
1054  * index.
1055  */
1056 static struct thread *
1057 runq_steal_from(struct runq *rq, int cpu, u_char start)
1058 {
1059  struct rqbits *rqb;
1060  struct rqhead *rqh;
1061  struct thread *td, *first;
1062  int bit;
1063  int i;
1064 
1065  rqb = &rq->rq_status;
1066  bit = start & (RQB_BPW -1);
1067  first = NULL;
1068 again:
1069  for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) {
1070  if (rqb->rqb_bits[i] == 0)
1071  continue;
1072  if (bit == 0)
1073  bit = RQB_FFS(rqb->rqb_bits[i]);
1074  for (; bit < RQB_BPW; bit++) {
1075  if ((rqb->rqb_bits[i] & (1ul << bit)) == 0)
1076  continue;
1077  rqh = &rq->rq_queues[bit + (i << RQB_L2BPW)];
1078  TAILQ_FOREACH(td, rqh, td_runq) {
1079  if (first && THREAD_CAN_MIGRATE(td) &&
1080  THREAD_CAN_SCHED(td, cpu))
1081  return (td);
1082  first = td;
1083  }
1084  }
1085  }
1086  if (start != 0) {
1087  start = 0;
1088  goto again;
1089  }
1090 
1091  if (first && THREAD_CAN_MIGRATE(first) &&
1092  THREAD_CAN_SCHED(first, cpu))
1093  return (first);
1094  return (NULL);
1095 }
1096 
1097 /*
1098  * Steals load from a standard linear queue.
1099  */
1100 static struct thread *
1101 runq_steal(struct runq *rq, int cpu)
1102 {
1103  struct rqhead *rqh;
1104  struct rqbits *rqb;
1105  struct thread *td;
1106  int word;
1107  int bit;
1108 
1109  rqb = &rq->rq_status;
1110  for (word = 0; word < RQB_LEN; word++) {
1111  if (rqb->rqb_bits[word] == 0)
1112  continue;
1113  for (bit = 0; bit < RQB_BPW; bit++) {
1114  if ((rqb->rqb_bits[word] & (1ul << bit)) == 0)
1115  continue;
1116  rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)];
1117  TAILQ_FOREACH(td, rqh, td_runq)
1118  if (THREAD_CAN_MIGRATE(td) &&
1119  THREAD_CAN_SCHED(td, cpu))
1120  return (td);
1121  }
1122  }
1123  return (NULL);
1124 }
1125 
1126 /*
1127  * Attempt to steal a thread in priority order from a thread queue.
1128  */
1129 static struct thread *
1130 tdq_steal(struct tdq *tdq, int cpu)
1131 {
1132  struct thread *td;
1133 
1134  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
1135  if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL)
1136  return (td);
1137  if ((td = runq_steal_from(&tdq->tdq_timeshare,
1138  cpu, tdq->tdq_ridx)) != NULL)
1139  return (td);
1140  return (runq_steal(&tdq->tdq_idle, cpu));
1141 }
1142 
1143 /*
1144  * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the
1145  * current lock and returns with the assigned queue locked.
1146  */
1147 static inline struct tdq *
1148 sched_setcpu(struct thread *td, int cpu, int flags)
1149 {
1150 
1151  struct tdq *tdq;
1152 
1153  THREAD_LOCK_ASSERT(td, MA_OWNED);
1154  tdq = TDQ_CPU(cpu);
1155  td->td_sched->ts_cpu = cpu;
1156  /*
1157  * If the lock matches just return the queue.
1158  */
1159  if (td->td_lock == TDQ_LOCKPTR(tdq))
1160  return (tdq);
1161 #ifdef notyet
1162  /*
1163  * If the thread isn't running its lockptr is a
1164  * turnstile or a sleepqueue. We can just lock_set without
1165  * blocking.
1166  */
1167  if (TD_CAN_RUN(td)) {
1168  TDQ_LOCK(tdq);
1169  thread_lock_set(td, TDQ_LOCKPTR(tdq));
1170  return (tdq);
1171  }
1172 #endif
1173  /*
1174  * The hard case, migration, we need to block the thread first to
1175  * prevent order reversals with other cpus locks.
1176  */
1177  spinlock_enter();
1178  thread_lock_block(td);
1179  TDQ_LOCK(tdq);
1180  thread_lock_unblock(td, TDQ_LOCKPTR(tdq));
1181  spinlock_exit();
1182  return (tdq);
1183 }
1184 
1185 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding");
1186 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity");
1187 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity");
1188 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load");
1189 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu");
1190 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration");
1191 
1192 static int
1193 sched_pickcpu(struct thread *td, int flags)
1194 {
1195  struct cpu_group *cg, *ccg;
1196  struct td_sched *ts;
1197  struct tdq *tdq;
1198  cpuset_t mask;
1199  int cpu, pri, self;
1200 
1201  self = PCPU_GET(cpuid);
1202  ts = td->td_sched;
1203  if (smp_started == 0)
1204  return (self);
1205  /*
1206  * Don't migrate a running thread from sched_switch().
1207  */
1208  if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td))
1209  return (ts->ts_cpu);
1210  /*
1211  * Prefer to run interrupt threads on the processors that generate
1212  * the interrupt.
1213  */
1214  pri = td->td_priority;
1215  if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) &&
1216  curthread->td_intr_nesting_level && ts->ts_cpu != self) {
1217  SCHED_STAT_INC(pickcpu_intrbind);
1218  ts->ts_cpu = self;
1219  if (TDQ_CPU(self)->tdq_lowpri > pri) {
1220  SCHED_STAT_INC(pickcpu_affinity);
1221  return (ts->ts_cpu);
1222  }
1223  }
1224  /*
1225  * If the thread can run on the last cpu and the affinity has not
1226  * expired or it is idle run it there.
1227  */
1228  tdq = TDQ_CPU(ts->ts_cpu);
1229  cg = tdq->tdq_cg;
1230  if (THREAD_CAN_SCHED(td, ts->ts_cpu) &&
1231  tdq->tdq_lowpri >= PRI_MIN_IDLE &&
1232  SCHED_AFFINITY(ts, CG_SHARE_L2)) {
1233  if (cg->cg_flags & CG_FLAG_THREAD) {
1234  CPUSET_FOREACH(cpu, cg->cg_mask) {
1235  if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE)
1236  break;
1237  }
1238  } else
1239  cpu = INT_MAX;
1240  if (cpu > mp_maxid) {
1241  SCHED_STAT_INC(pickcpu_idle_affinity);
1242  return (ts->ts_cpu);
1243  }
1244  }
1245  /*
1246  * Search for the last level cache CPU group in the tree.
1247  * Skip caches with expired affinity time and SMT groups.
1248  * Affinity to higher level caches will be handled less aggressively.
1249  */
1250  for (ccg = NULL; cg != NULL; cg = cg->cg_parent) {
1251  if (cg->cg_flags & CG_FLAG_THREAD)
1252  continue;
1253  if (!SCHED_AFFINITY(ts, cg->cg_level))
1254  continue;
1255  ccg = cg;
1256  }
1257  if (ccg != NULL)
1258  cg = ccg;
1259  cpu = -1;
1260  /* Search the group for the less loaded idle CPU we can run now. */
1261  mask = td->td_cpuset->cs_mask;
1262  if (cg != NULL && cg != cpu_top &&
1263  CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0)
1264  cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE),
1265  INT_MAX, ts->ts_cpu);
1266  /* Search globally for the less loaded CPU we can run now. */
1267  if (cpu == -1)
1268  cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu);
1269  /* Search globally for the less loaded CPU. */
1270  if (cpu == -1)
1271  cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu);
1272  KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu."));
1273  /*
1274  * Compare the lowest loaded cpu to current cpu.
1275  */
1276  if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri &&
1277  TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE &&
1278  TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) {
1279  SCHED_STAT_INC(pickcpu_local);
1280  cpu = self;
1281  } else
1282  SCHED_STAT_INC(pickcpu_lowest);
1283  if (cpu != ts->ts_cpu)
1284  SCHED_STAT_INC(pickcpu_migration);
1285  return (cpu);
1286 }
1287 #endif
1288 
1289 /*
1290  * Pick the highest priority task we have and return it.
1291  */
1292 static struct thread *
1293 tdq_choose(struct tdq *tdq)
1294 {
1295  struct thread *td;
1296 
1297  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
1298  td = runq_choose(&tdq->tdq_realtime);
1299  if (td != NULL)
1300  return (td);
1301  td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx);
1302  if (td != NULL) {
1303  KASSERT(td->td_priority >= PRI_MIN_BATCH,
1304  ("tdq_choose: Invalid priority on timeshare queue %d",
1305  td->td_priority));
1306  return (td);
1307  }
1308  td = runq_choose(&tdq->tdq_idle);
1309  if (td != NULL) {
1310  KASSERT(td->td_priority >= PRI_MIN_IDLE,
1311  ("tdq_choose: Invalid priority on idle queue %d",
1312  td->td_priority));
1313  return (td);
1314  }
1315 
1316  return (NULL);
1317 }
1318 
1319 /*
1320  * Initialize a thread queue.
1321  */
1322 static void
1323 tdq_setup(struct tdq *tdq)
1324 {
1325 
1326  if (bootverbose)
1327  printf("ULE: setup cpu %d\n", TDQ_ID(tdq));
1328  runq_init(&tdq->tdq_realtime);
1329  runq_init(&tdq->tdq_timeshare);
1330  runq_init(&tdq->tdq_idle);
1331  snprintf(tdq->tdq_name, sizeof(tdq->tdq_name),
1332  "sched lock %d", (int)TDQ_ID(tdq));
1333  mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock",
1334  MTX_SPIN | MTX_RECURSE);
1335 #ifdef KTR
1336  snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname),
1337  "CPU %d load", (int)TDQ_ID(tdq));
1338 #endif
1339 }
1340 
1341 #ifdef SMP
1342 static void
1343 sched_setup_smp(void)
1344 {
1345  struct tdq *tdq;
1346  int i;
1347 
1348  cpu_top = smp_topo();
1349  CPU_FOREACH(i) {
1350  tdq = TDQ_CPU(i);
1351  tdq_setup(tdq);
1352  tdq->tdq_cg = smp_topo_find(cpu_top, i);
1353  if (tdq->tdq_cg == NULL)
1354  panic("Can't find cpu group for %d\n", i);
1355  }
1356  balance_tdq = TDQ_SELF();
1357  sched_balance();
1358 }
1359 #endif
1360 
1361 /*
1362  * Setup the thread queues and initialize the topology based on MD
1363  * information.
1364  */
1365 static void
1367 {
1368  struct tdq *tdq;
1369 
1370  tdq = TDQ_SELF();
1371 #ifdef SMP
1372  sched_setup_smp();
1373 #else
1374  tdq_setup(tdq);
1375 #endif
1376 
1377  /* Add thread0's load since it's running. */
1378  TDQ_LOCK(tdq);
1379  thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF());
1380  tdq_load_add(tdq, &thread0);
1381  tdq->tdq_lowpri = thread0.td_priority;
1382  TDQ_UNLOCK(tdq);
1383 }
1384 
1385 /*
1386  * This routine determines time constants after stathz and hz are setup.
1387  */
1388 /* ARGSUSED */
1389 static void
1391 {
1392  int incr;
1393 
1394  realstathz = stathz ? stathz : hz;
1397  hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
1398  realstathz);
1399 
1400  /*
1401  * tickincr is shifted out by 10 to avoid rounding errors due to
1402  * hz not being evenly divisible by stathz on all platforms.
1403  */
1404  incr = (hz << SCHED_TICK_SHIFT) / realstathz;
1405  /*
1406  * This does not work for values of stathz that are more than
1407  * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen.
1408  */
1409  if (incr == 0)
1410  incr = 1;
1411  tickincr = incr;
1412 #ifdef SMP
1413  /*
1414  * Set the default balance interval now that we know
1415  * what realstathz is.
1416  */
1417  balance_interval = realstathz;
1418  affinity = SCHED_AFFINITY_DEFAULT;
1419 #endif
1420  if (sched_idlespinthresh < 0)
1421  sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz;
1422 }
1423 
1424 
1425 /*
1426  * This is the core of the interactivity algorithm. Determines a score based
1427  * on past behavior. It is the ratio of sleep time to run time scaled to
1428  * a [0, 100] integer. This is the voluntary sleep time of a process, which
1429  * differs from the cpu usage because it does not account for time spent
1430  * waiting on a run-queue. Would be prettier if we had floating point.
1431  */
1432 static int
1433 sched_interact_score(struct thread *td)
1434 {
1435  struct td_sched *ts;
1436  int div;
1437 
1438  ts = td->td_sched;
1439  /*
1440  * The score is only needed if this is likely to be an interactive
1441  * task. Don't go through the expense of computing it if there's
1442  * no chance.
1443  */
1445  ts->ts_runtime >= ts->ts_slptime)
1446  return (SCHED_INTERACT_HALF);
1447 
1448  if (ts->ts_runtime > ts->ts_slptime) {
1449  div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF);
1450  return (SCHED_INTERACT_HALF +
1451  (SCHED_INTERACT_HALF - (ts->ts_slptime / div)));
1452  }
1453  if (ts->ts_slptime > ts->ts_runtime) {
1454  div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF);
1455  return (ts->ts_runtime / div);
1456  }
1457  /* runtime == slptime */
1458  if (ts->ts_runtime)
1459  return (SCHED_INTERACT_HALF);
1460 
1461  /*
1462  * This can happen if slptime and runtime are 0.
1463  */
1464  return (0);
1465 
1466 }
1467 
1468 /*
1469  * Scale the scheduling priority according to the "interactivity" of this
1470  * process.
1471  */
1472 static void
1473 sched_priority(struct thread *td)
1474 {
1475  int score;
1476  int pri;
1477 
1478  if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE)
1479  return;
1480  /*
1481  * If the score is interactive we place the thread in the realtime
1482  * queue with a priority that is less than kernel and interrupt
1483  * priorities. These threads are not subject to nice restrictions.
1484  *
1485  * Scores greater than this are placed on the normal timeshare queue
1486  * where the priority is partially decided by the most recent cpu
1487  * utilization and the rest is decided by nice value.
1488  *
1489  * The nice value of the process has a linear effect on the calculated
1490  * score. Negative nice values make it easier for a thread to be
1491  * considered interactive.
1492  */
1493  score = imax(0, sched_interact_score(td) + td->td_proc->p_nice);
1494  if (score < sched_interact) {
1495  pri = PRI_MIN_INTERACT;
1496  pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) /
1497  sched_interact) * score;
1498  KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT,
1499  ("sched_priority: invalid interactive priority %d score %d",
1500  pri, score));
1501  } else {
1502  pri = SCHED_PRI_MIN;
1503  if (td->td_sched->ts_ticks)
1504  pri += min(SCHED_PRI_TICKS(td->td_sched),
1505  SCHED_PRI_RANGE - 1);
1506  pri += SCHED_PRI_NICE(td->td_proc->p_nice);
1507  KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH,
1508  ("sched_priority: invalid priority %d: nice %d, "
1509  "ticks %d ftick %d ltick %d tick pri %d",
1510  pri, td->td_proc->p_nice, td->td_sched->ts_ticks,
1511  td->td_sched->ts_ftick, td->td_sched->ts_ltick,
1512  SCHED_PRI_TICKS(td->td_sched)));
1513  }
1514  sched_user_prio(td, pri);
1515 
1516  return;
1517 }
1518 
1519 /*
1520  * This routine enforces a maximum limit on the amount of scheduling history
1521  * kept. It is called after either the slptime or runtime is adjusted. This
1522  * function is ugly due to integer math.
1523  */
1524 static void
1525 sched_interact_update(struct thread *td)
1526 {
1527  struct td_sched *ts;
1528  u_int sum;
1529 
1530  ts = td->td_sched;
1531  sum = ts->ts_runtime + ts->ts_slptime;
1532  if (sum < SCHED_SLP_RUN_MAX)
1533  return;
1534  /*
1535  * This only happens from two places:
1536  * 1) We have added an unusual amount of run time from fork_exit.
1537  * 2) We have added an unusual amount of sleep time from sched_sleep().
1538  */
1539  if (sum > SCHED_SLP_RUN_MAX * 2) {
1540  if (ts->ts_runtime > ts->ts_slptime) {
1542  ts->ts_slptime = 1;
1543  } else {
1545  ts->ts_runtime = 1;
1546  }
1547  return;
1548  }
1549  /*
1550  * If we have exceeded by more than 1/5th then the algorithm below
1551  * will not bring us back into range. Dividing by two here forces
1552  * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX]
1553  */
1554  if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) {
1555  ts->ts_runtime /= 2;
1556  ts->ts_slptime /= 2;
1557  return;
1558  }
1559  ts->ts_runtime = (ts->ts_runtime / 5) * 4;
1560  ts->ts_slptime = (ts->ts_slptime / 5) * 4;
1561 }
1562 
1563 /*
1564  * Scale back the interactivity history when a child thread is created. The
1565  * history is inherited from the parent but the thread may behave totally
1566  * differently. For example, a shell spawning a compiler process. We want
1567  * to learn that the compiler is behaving badly very quickly.
1568  */
1569 static void
1570 sched_interact_fork(struct thread *td)
1571 {
1572  int ratio;
1573  int sum;
1574 
1575  sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime;
1576  if (sum > SCHED_SLP_RUN_FORK) {
1577  ratio = sum / SCHED_SLP_RUN_FORK;
1578  td->td_sched->ts_runtime /= ratio;
1579  td->td_sched->ts_slptime /= ratio;
1580  }
1581 }
1582 
1583 /*
1584  * Called from proc0_init() to setup the scheduler fields.
1585  */
1586 void
1588 {
1589 
1590  /*
1591  * Set up the scheduler specific parts of proc0.
1592  */
1593  proc0.p_sched = NULL; /* XXX */
1594  thread0.td_sched = &td_sched0;
1597  td_sched0.ts_slice = 0;
1598 }
1599 
1600 /*
1601  * This is only somewhat accurate since given many processes of the same
1602  * priority they will switch when their slices run out, which will be
1603  * at most sched_slice stathz ticks.
1604  */
1605 int
1607 {
1608 
1609  /* Convert sched_slice from stathz to hz. */
1610  return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz));
1611 }
1612 
1613 /*
1614  * Update the percent cpu tracking information when it is requested or
1615  * the total history exceeds the maximum. We keep a sliding history of
1616  * tick counts that slowly decays. This is less precise than the 4BSD
1617  * mechanism since it happens with less regular and frequent events.
1618  */
1619 static void
1620 sched_pctcpu_update(struct td_sched *ts, int run)
1621 {
1622  int t = ticks;
1623 
1624  if (t - ts->ts_ltick >= SCHED_TICK_TARG) {
1625  ts->ts_ticks = 0;
1626  ts->ts_ftick = t - SCHED_TICK_TARG;
1627  } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) {
1628  ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) *
1629  (ts->ts_ltick - (t - SCHED_TICK_TARG));
1630  ts->ts_ftick = t - SCHED_TICK_TARG;
1631  }
1632  if (run)
1633  ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT;
1634  ts->ts_ltick = t;
1635 }
1636 
1637 /*
1638  * Adjust the priority of a thread. Move it to the appropriate run-queue
1639  * if necessary. This is the back-end for several priority related
1640  * functions.
1641  */
1642 static void
1643 sched_thread_priority(struct thread *td, u_char prio)
1644 {
1645  struct td_sched *ts;
1646  struct tdq *tdq;
1647  int oldpri;
1648 
1649  KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio",
1650  "prio:%d", td->td_priority, "new prio:%d", prio,
1651  KTR_ATTR_LINKED, sched_tdname(curthread));
1652  SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio);
1653  if (td != curthread && prio < td->td_priority) {
1654  KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread),
1655  "lend prio", "prio:%d", td->td_priority, "new prio:%d",
1656  prio, KTR_ATTR_LINKED, sched_tdname(td));
1657  SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio,
1658  curthread);
1659  }
1660  ts = td->td_sched;
1661  THREAD_LOCK_ASSERT(td, MA_OWNED);
1662  if (td->td_priority == prio)
1663  return;
1664  /*
1665  * If the priority has been elevated due to priority
1666  * propagation, we may have to move ourselves to a new
1667  * queue. This could be optimized to not re-add in some
1668  * cases.
1669  */
1670  if (TD_ON_RUNQ(td) && prio < td->td_priority) {
1671  sched_rem(td);
1672  td->td_priority = prio;
1673  sched_add(td, SRQ_BORROWING);
1674  return;
1675  }
1676  /*
1677  * If the thread is currently running we may have to adjust the lowpri
1678  * information so other cpus are aware of our current priority.
1679  */
1680  if (TD_IS_RUNNING(td)) {
1681  tdq = TDQ_CPU(ts->ts_cpu);
1682  oldpri = td->td_priority;
1683  td->td_priority = prio;
1684  if (prio < tdq->tdq_lowpri)
1685  tdq->tdq_lowpri = prio;
1686  else if (tdq->tdq_lowpri == oldpri)
1687  tdq_setlowpri(tdq, td);
1688  return;
1689  }
1690  td->td_priority = prio;
1691 }
1692 
1693 /*
1694  * Update a thread's priority when it is lent another thread's
1695  * priority.
1696  */
1697 void
1698 sched_lend_prio(struct thread *td, u_char prio)
1699 {
1700 
1701  td->td_flags |= TDF_BORROWING;
1702  sched_thread_priority(td, prio);
1703 }
1704 
1705 /*
1706  * Restore a thread's priority when priority propagation is
1707  * over. The prio argument is the minimum priority the thread
1708  * needs to have to satisfy other possible priority lending
1709  * requests. If the thread's regular priority is less
1710  * important than prio, the thread will keep a priority boost
1711  * of prio.
1712  */
1713 void
1714 sched_unlend_prio(struct thread *td, u_char prio)
1715 {
1716  u_char base_pri;
1717 
1718  if (td->td_base_pri >= PRI_MIN_TIMESHARE &&
1719  td->td_base_pri <= PRI_MAX_TIMESHARE)
1720  base_pri = td->td_user_pri;
1721  else
1722  base_pri = td->td_base_pri;
1723  if (prio >= base_pri) {
1724  td->td_flags &= ~TDF_BORROWING;
1725  sched_thread_priority(td, base_pri);
1726  } else
1727  sched_lend_prio(td, prio);
1728 }
1729 
1730 /*
1731  * Standard entry for setting the priority to an absolute value.
1732  */
1733 void
1734 sched_prio(struct thread *td, u_char prio)
1735 {
1736  u_char oldprio;
1737 
1738  /* First, update the base priority. */
1739  td->td_base_pri = prio;
1740 
1741  /*
1742  * If the thread is borrowing another thread's priority, don't
1743  * ever lower the priority.
1744  */
1745  if (td->td_flags & TDF_BORROWING && td->td_priority < prio)
1746  return;
1747 
1748  /* Change the real priority. */
1749  oldprio = td->td_priority;
1750  sched_thread_priority(td, prio);
1751 
1752  /*
1753  * If the thread is on a turnstile, then let the turnstile update
1754  * its state.
1755  */
1756  if (TD_ON_LOCK(td) && oldprio != prio)
1757  turnstile_adjust(td, oldprio);
1758 }
1759 
1760 /*
1761  * Set the base user priority, does not effect current running priority.
1762  */
1763 void
1764 sched_user_prio(struct thread *td, u_char prio)
1765 {
1766 
1767  td->td_base_user_pri = prio;
1768  if (td->td_lend_user_pri <= prio)
1769  return;
1770  td->td_user_pri = prio;
1771 }
1772 
1773 void
1774 sched_lend_user_prio(struct thread *td, u_char prio)
1775 {
1776 
1777  THREAD_LOCK_ASSERT(td, MA_OWNED);
1778  td->td_lend_user_pri = prio;
1779  td->td_user_pri = min(prio, td->td_base_user_pri);
1780  if (td->td_priority > td->td_user_pri)
1781  sched_prio(td, td->td_user_pri);
1782  else if (td->td_priority != td->td_user_pri)
1783  td->td_flags |= TDF_NEEDRESCHED;
1784 }
1785 
1786 /*
1787  * Handle migration from sched_switch(). This happens only for
1788  * cpu binding.
1789  */
1790 static struct mtx *
1791 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags)
1792 {
1793  struct tdq *tdn;
1794 
1795  tdn = TDQ_CPU(td->td_sched->ts_cpu);
1796 #ifdef SMP
1797  tdq_load_rem(tdq, td);
1798  /*
1799  * Do the lock dance required to avoid LOR. We grab an extra
1800  * spinlock nesting to prevent preemption while we're
1801  * not holding either run-queue lock.
1802  */
1803  spinlock_enter();
1804  thread_lock_block(td); /* This releases the lock on tdq. */
1805 
1806  /*
1807  * Acquire both run-queue locks before placing the thread on the new
1808  * run-queue to avoid deadlocks created by placing a thread with a
1809  * blocked lock on the run-queue of a remote processor. The deadlock
1810  * occurs when a third processor attempts to lock the two queues in
1811  * question while the target processor is spinning with its own
1812  * run-queue lock held while waiting for the blocked lock to clear.
1813  */
1814  tdq_lock_pair(tdn, tdq);
1815  tdq_add(tdn, td, flags);
1816  tdq_notify(tdn, td);
1817  TDQ_UNLOCK(tdn);
1818  spinlock_exit();
1819 #endif
1820  return (TDQ_LOCKPTR(tdn));
1821 }
1822 
1823 /*
1824  * Variadic version of thread_lock_unblock() that does not assume td_lock
1825  * is blocked.
1826  */
1827 static inline void
1828 thread_unblock_switch(struct thread *td, struct mtx *mtx)
1829 {
1830  atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock,
1831  (uintptr_t)mtx);
1832 }
1833 
1834 /*
1835  * Switch threads. This function has to handle threads coming in while
1836  * blocked for some reason, running, or idle. It also must deal with
1837  * migrating a thread from one queue to another as running threads may
1838  * be assigned elsewhere via binding.
1839  */
1840 void
1841 sched_switch(struct thread *td, struct thread *newtd, int flags)
1842 {
1843  struct tdq *tdq;
1844  struct td_sched *ts;
1845  struct mtx *mtx;
1846  int srqflag;
1847  int cpuid, preempted;
1848 
1849  THREAD_LOCK_ASSERT(td, MA_OWNED);
1850  KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument"));
1851 
1852  cpuid = PCPU_GET(cpuid);
1853  tdq = TDQ_CPU(cpuid);
1854  ts = td->td_sched;
1855  mtx = td->td_lock;
1856  sched_pctcpu_update(ts, 1);
1857  ts->ts_rltick = ticks;
1858  td->td_lastcpu = td->td_oncpu;
1859  td->td_oncpu = NOCPU;
1860  preempted = !((td->td_flags & TDF_SLICEEND) ||
1861  (flags & SWT_RELINQUISH));
1862  td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND);
1863  td->td_owepreempt = 0;
1864  if (!TD_IS_IDLETHREAD(td))
1865  tdq->tdq_switchcnt++;
1866  /*
1867  * The lock pointer in an idle thread should never change. Reset it
1868  * to CAN_RUN as well.
1869  */
1870  if (TD_IS_IDLETHREAD(td)) {
1871  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1872  TD_SET_CAN_RUN(td);
1873  } else if (TD_IS_RUNNING(td)) {
1874  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1875  srqflag = preempted ?
1876  SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
1877  SRQ_OURSELF|SRQ_YIELDING;
1878 #ifdef SMP
1879  if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu))
1880  ts->ts_cpu = sched_pickcpu(td, 0);
1881 #endif
1882  if (ts->ts_cpu == cpuid)
1883  tdq_runq_add(tdq, td, srqflag);
1884  else {
1885  KASSERT(THREAD_CAN_MIGRATE(td) ||
1886  (ts->ts_flags & TSF_BOUND) != 0,
1887  ("Thread %p shouldn't migrate", td));
1888  mtx = sched_switch_migrate(tdq, td, srqflag);
1889  }
1890  } else {
1891  /* This thread must be going to sleep. */
1892  TDQ_LOCK(tdq);
1893  mtx = thread_lock_block(td);
1894  tdq_load_rem(tdq, td);
1895  }
1896  /*
1897  * We enter here with the thread blocked and assigned to the
1898  * appropriate cpu run-queue or sleep-queue and with the current
1899  * thread-queue locked.
1900  */
1901  TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED);
1902  newtd = choosethread();
1903  /*
1904  * Call the MD code to switch contexts if necessary.
1905  */
1906  if (td != newtd) {
1907 #ifdef HWPMC_HOOKS
1908  if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1909  PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
1910 #endif
1911  SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc);
1912  lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object);
1913  TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd;
1914  sched_pctcpu_update(newtd->td_sched, 0);
1915 
1916 #ifdef KDTRACE_HOOKS
1917  /*
1918  * If DTrace has set the active vtime enum to anything
1919  * other than INACTIVE (0), then it should have set the
1920  * function to call.
1921  */
1922  if (dtrace_vtime_active)
1923  (*dtrace_vtime_switch_func)(newtd);
1924 #endif
1925 
1926  cpu_switch(td, newtd, mtx);
1927  /*
1928  * We may return from cpu_switch on a different cpu. However,
1929  * we always return with td_lock pointing to the current cpu's
1930  * run queue lock.
1931  */
1932  cpuid = PCPU_GET(cpuid);
1933  tdq = TDQ_CPU(cpuid);
1934  lock_profile_obtain_lock_success(
1935  &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__);
1936 
1937  SDT_PROBE0(sched, , , on__cpu);
1938 #ifdef HWPMC_HOOKS
1939  if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1940  PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
1941 #endif
1942  } else {
1943  thread_unblock_switch(td, mtx);
1944  SDT_PROBE0(sched, , , remain__cpu);
1945  }
1946  /*
1947  * Assert that all went well and return.
1948  */
1949  TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED);
1950  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1951  td->td_oncpu = cpuid;
1952 }
1953 
1954 /*
1955  * Adjust thread priorities as a result of a nice request.
1956  */
1957 void
1958 sched_nice(struct proc *p, int nice)
1959 {
1960  struct thread *td;
1961 
1962  PROC_LOCK_ASSERT(p, MA_OWNED);
1963 
1964  p->p_nice = nice;
1965  FOREACH_THREAD_IN_PROC(p, td) {
1966  thread_lock(td);
1967  sched_priority(td);
1968  sched_prio(td, td->td_base_user_pri);
1969  thread_unlock(td);
1970  }
1971 }
1972 
1973 /*
1974  * Record the sleep time for the interactivity scorer.
1975  */
1976 void
1977 sched_sleep(struct thread *td, int prio)
1978 {
1979 
1980  THREAD_LOCK_ASSERT(td, MA_OWNED);
1981 
1982  td->td_slptick = ticks;
1983  if (TD_IS_SUSPENDED(td) || prio >= PSOCK)
1984  td->td_flags |= TDF_CANSWAP;
1985  if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE)
1986  return;
1987  if (static_boost == 1 && prio)
1988  sched_prio(td, prio);
1989  else if (static_boost && td->td_priority > static_boost)
1990  sched_prio(td, static_boost);
1991 }
1992 
1993 /*
1994  * Schedule a thread to resume execution and record how long it voluntarily
1995  * slept. We also update the pctcpu, interactivity, and priority.
1996  */
1997 void
1998 sched_wakeup(struct thread *td)
1999 {
2000  struct td_sched *ts;
2001  int slptick;
2002 
2003  THREAD_LOCK_ASSERT(td, MA_OWNED);
2004  ts = td->td_sched;
2005  td->td_flags &= ~TDF_CANSWAP;
2006  /*
2007  * If we slept for more than a tick update our interactivity and
2008  * priority.
2009  */
2010  slptick = td->td_slptick;
2011  td->td_slptick = 0;
2012  if (slptick && slptick != ticks) {
2013  ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT;
2015  sched_pctcpu_update(ts, 0);
2016  }
2017  /*
2018  * Reset the slice value since we slept and advanced the round-robin.
2019  */
2020  ts->ts_slice = 0;
2021  sched_add(td, SRQ_BORING);
2022 }
2023 
2024 /*
2025  * Penalize the parent for creating a new child and initialize the child's
2026  * priority.
2027  */
2028 void
2029 sched_fork(struct thread *td, struct thread *child)
2030 {
2031  THREAD_LOCK_ASSERT(td, MA_OWNED);
2032  sched_pctcpu_update(td->td_sched, 1);
2033  sched_fork_thread(td, child);
2034  /*
2035  * Penalize the parent and child for forking.
2036  */
2037  sched_interact_fork(child);
2038  sched_priority(child);
2039  td->td_sched->ts_runtime += tickincr;
2041  sched_priority(td);
2042 }
2043 
2044 /*
2045  * Fork a new thread, may be within the same process.
2046  */
2047 void
2048 sched_fork_thread(struct thread *td, struct thread *child)
2049 {
2050  struct td_sched *ts;
2051  struct td_sched *ts2;
2052  struct tdq *tdq;
2053 
2054  tdq = TDQ_SELF();
2055  THREAD_LOCK_ASSERT(td, MA_OWNED);
2056  /*
2057  * Initialize child.
2058  */
2059  ts = td->td_sched;
2060  ts2 = child->td_sched;
2061  child->td_lock = TDQ_LOCKPTR(tdq);
2062  child->td_cpuset = cpuset_ref(td->td_cpuset);
2063  ts2->ts_cpu = ts->ts_cpu;
2064  ts2->ts_flags = 0;
2065  /*
2066  * Grab our parents cpu estimation information.
2067  */
2068  ts2->ts_ticks = ts->ts_ticks;
2069  ts2->ts_ltick = ts->ts_ltick;
2070  ts2->ts_ftick = ts->ts_ftick;
2071  /*
2072  * Do not inherit any borrowed priority from the parent.
2073  */
2074  child->td_priority = child->td_base_pri;
2075  /*
2076  * And update interactivity score.
2077  */
2078  ts2->ts_slptime = ts->ts_slptime;
2079  ts2->ts_runtime = ts->ts_runtime;
2080  /* Attempt to quickly learn interactivity. */
2081  ts2->ts_slice = tdq_slice(tdq) - sched_slice_min;
2082 #ifdef KTR
2083  bzero(ts2->ts_name, sizeof(ts2->ts_name));
2084 #endif
2085 }
2086 
2087 /*
2088  * Adjust the priority class of a thread.
2089  */
2090 void
2091 sched_class(struct thread *td, int class)
2092 {
2093 
2094  THREAD_LOCK_ASSERT(td, MA_OWNED);
2095  if (td->td_pri_class == class)
2096  return;
2097  td->td_pri_class = class;
2098 }
2099 
2100 /*
2101  * Return some of the child's priority and interactivity to the parent.
2102  */
2103 void
2104 sched_exit(struct proc *p, struct thread *child)
2105 {
2106  struct thread *td;
2107 
2108  KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit",
2109  "prio:%d", child->td_priority);
2110  PROC_LOCK_ASSERT(p, MA_OWNED);
2111  td = FIRST_THREAD_IN_PROC(p);
2112  sched_exit_thread(td, child);
2113 }
2114 
2115 /*
2116  * Penalize another thread for the time spent on this one. This helps to
2117  * worsen the priority and interactivity of processes which schedule batch
2118  * jobs such as make. This has little effect on the make process itself but
2119  * causes new processes spawned by it to receive worse scores immediately.
2120  */
2121 void
2122 sched_exit_thread(struct thread *td, struct thread *child)
2123 {
2124 
2125  KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit",
2126  "prio:%d", child->td_priority);
2127  /*
2128  * Give the child's runtime to the parent without returning the
2129  * sleep time as a penalty to the parent. This causes shells that
2130  * launch expensive things to mark their children as expensive.
2131  */
2132  thread_lock(td);
2133  td->td_sched->ts_runtime += child->td_sched->ts_runtime;
2135  sched_priority(td);
2136  thread_unlock(td);
2137 }
2138 
2139 void
2140 sched_preempt(struct thread *td)
2141 {
2142  struct tdq *tdq;
2143 
2144  SDT_PROBE2(sched, , , surrender, td, td->td_proc);
2145 
2146  thread_lock(td);
2147  tdq = TDQ_SELF();
2148  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2149  tdq->tdq_ipipending = 0;
2150  if (td->td_priority > tdq->tdq_lowpri) {
2151  int flags;
2152 
2153  flags = SW_INVOL | SW_PREEMPT;
2154  if (td->td_critnest > 1)
2155  td->td_owepreempt = 1;
2156  else if (TD_IS_IDLETHREAD(td))
2157  mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL);
2158  else
2159  mi_switch(flags | SWT_REMOTEPREEMPT, NULL);
2160  }
2161  thread_unlock(td);
2162 }
2163 
2164 /*
2165  * Fix priorities on return to user-space. Priorities may be elevated due
2166  * to static priorities in msleep() or similar.
2167  */
2168 void
2169 sched_userret(struct thread *td)
2170 {
2171  /*
2172  * XXX we cheat slightly on the locking here to avoid locking in
2173  * the usual case. Setting td_priority here is essentially an
2174  * incomplete workaround for not setting it properly elsewhere.
2175  * Now that some interrupt handlers are threads, not setting it
2176  * properly elsewhere can clobber it in the window between setting
2177  * it here and returning to user mode, so don't waste time setting
2178  * it perfectly here.
2179  */
2180  KASSERT((td->td_flags & TDF_BORROWING) == 0,
2181  ("thread with borrowed priority returning to userland"));
2182  if (td->td_priority != td->td_user_pri) {
2183  thread_lock(td);
2184  td->td_priority = td->td_user_pri;
2185  td->td_base_pri = td->td_user_pri;
2186  tdq_setlowpri(TDQ_SELF(), td);
2187  thread_unlock(td);
2188  }
2189 }
2190 
2191 /*
2192  * Handle a stathz tick. This is really only relevant for timeshare
2193  * threads.
2194  */
2195 void
2196 sched_clock(struct thread *td)
2197 {
2198  struct tdq *tdq;
2199  struct td_sched *ts;
2200 
2201  THREAD_LOCK_ASSERT(td, MA_OWNED);
2202  tdq = TDQ_SELF();
2203 #ifdef SMP
2204  /*
2205  * We run the long term load balancer infrequently on the first cpu.
2206  */
2207  if (balance_tdq == tdq) {
2208  if (balance_ticks && --balance_ticks == 0)
2209  sched_balance();
2210  }
2211 #endif
2212  /*
2213  * Save the old switch count so we have a record of the last ticks
2214  * activity. Initialize the new switch count based on our load.
2215  * If there is some activity seed it to reflect that.
2216  */
2217  tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt;
2218  tdq->tdq_switchcnt = tdq->tdq_load;
2219  /*
2220  * Advance the insert index once for each tick to ensure that all
2221  * threads get a chance to run.
2222  */
2223  if (tdq->tdq_idx == tdq->tdq_ridx) {
2224  tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS;
2225  if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx]))
2226  tdq->tdq_ridx = tdq->tdq_idx;
2227  }
2228  ts = td->td_sched;
2229  sched_pctcpu_update(ts, 1);
2230  if (td->td_pri_class & PRI_FIFO_BIT)
2231  return;
2232  if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) {
2233  /*
2234  * We used a tick; charge it to the thread so
2235  * that we can compute our interactivity.
2236  */
2237  td->td_sched->ts_runtime += tickincr;
2239  sched_priority(td);
2240  }
2241 
2242  /*
2243  * Force a context switch if the current thread has used up a full
2244  * time slice (default is 100ms).
2245  */
2246  if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) {
2247  ts->ts_slice = 0;
2248  td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND;
2249  }
2250 }
2251 
2252 /*
2253  * Called once per hz tick.
2254  */
2255 void
2256 sched_tick(int cnt)
2257 {
2258 
2259 }
2260 
2261 /*
2262  * Return whether the current CPU has runnable tasks. Used for in-kernel
2263  * cooperative idle threads.
2264  */
2265 int
2267 {
2268  struct tdq *tdq;
2269  int load;
2270 
2271  load = 1;
2272 
2273  tdq = TDQ_SELF();
2274  if ((curthread->td_flags & TDF_IDLETD) != 0) {
2275  if (tdq->tdq_load > 0)
2276  goto out;
2277  } else
2278  if (tdq->tdq_load - 1 > 0)
2279  goto out;
2280  load = 0;
2281 out:
2282  return (load);
2283 }
2284 
2285 /*
2286  * Choose the highest priority thread to run. The thread is removed from
2287  * the run-queue while running however the load remains. For SMP we set
2288  * the tdq in the global idle bitmask if it idles here.
2289  */
2290 struct thread *
2292 {
2293  struct thread *td;
2294  struct tdq *tdq;
2295 
2296  tdq = TDQ_SELF();
2297  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2298  td = tdq_choose(tdq);
2299  if (td) {
2300  tdq_runq_rem(tdq, td);
2301  tdq->tdq_lowpri = td->td_priority;
2302  return (td);
2303  }
2304  tdq->tdq_lowpri = PRI_MAX_IDLE;
2305  return (PCPU_GET(idlethread));
2306 }
2307 
2308 /*
2309  * Set owepreempt if necessary. Preemption never happens directly in ULE,
2310  * we always request it once we exit a critical section.
2311  */
2312 static inline void
2313 sched_setpreempt(struct thread *td)
2314 {
2315  struct thread *ctd;
2316  int cpri;
2317  int pri;
2318 
2319  THREAD_LOCK_ASSERT(curthread, MA_OWNED);
2320 
2321  ctd = curthread;
2322  pri = td->td_priority;
2323  cpri = ctd->td_priority;
2324  if (pri < cpri)
2325  ctd->td_flags |= TDF_NEEDRESCHED;
2326  if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd))
2327  return;
2328  if (!sched_shouldpreempt(pri, cpri, 0))
2329  return;
2330  ctd->td_owepreempt = 1;
2331 }
2332 
2333 /*
2334  * Add a thread to a thread queue. Select the appropriate runq and add the
2335  * thread to it. This is the internal function called when the tdq is
2336  * predetermined.
2337  */
2338 void
2339 tdq_add(struct tdq *tdq, struct thread *td, int flags)
2340 {
2341 
2342  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2343  KASSERT((td->td_inhibitors == 0),
2344  ("sched_add: trying to run inhibited thread"));
2345  KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
2346  ("sched_add: bad thread state"));
2347  KASSERT(td->td_flags & TDF_INMEM,
2348  ("sched_add: thread swapped out"));
2349 
2350  if (td->td_priority < tdq->tdq_lowpri)
2351  tdq->tdq_lowpri = td->td_priority;
2352  tdq_runq_add(tdq, td, flags);
2353  tdq_load_add(tdq, td);
2354 }
2355 
2356 /*
2357  * Select the target thread queue and add a thread to it. Request
2358  * preemption or IPI a remote processor if required.
2359  */
2360 void
2361 sched_add(struct thread *td, int flags)
2362 {
2363  struct tdq *tdq;
2364 #ifdef SMP
2365  int cpu;
2366 #endif
2367 
2368  KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
2369  "prio:%d", td->td_priority, KTR_ATTR_LINKED,
2370  sched_tdname(curthread));
2371  KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
2372  KTR_ATTR_LINKED, sched_tdname(td));
2373  SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL,
2374  flags & SRQ_PREEMPTED);
2375  THREAD_LOCK_ASSERT(td, MA_OWNED);
2376  /*
2377  * Recalculate the priority before we select the target cpu or
2378  * run-queue.
2379  */
2380  if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
2381  sched_priority(td);
2382 #ifdef SMP
2383  /*
2384  * Pick the destination cpu and if it isn't ours transfer to the
2385  * target cpu.
2386  */
2387  cpu = sched_pickcpu(td, flags);
2388  tdq = sched_setcpu(td, cpu, flags);
2389  tdq_add(tdq, td, flags);
2390  if (cpu != PCPU_GET(cpuid)) {
2391  tdq_notify(tdq, td);
2392  return;
2393  }
2394 #else
2395  tdq = TDQ_SELF();
2396  TDQ_LOCK(tdq);
2397  /*
2398  * Now that the thread is moving to the run-queue, set the lock
2399  * to the scheduler's lock.
2400  */
2401  thread_lock_set(td, TDQ_LOCKPTR(tdq));
2402  tdq_add(tdq, td, flags);
2403 #endif
2404  if (!(flags & SRQ_YIELDING))
2405  sched_setpreempt(td);
2406 }
2407 
2408 /*
2409  * Remove a thread from a run-queue without running it. This is used
2410  * when we're stealing a thread from a remote queue. Otherwise all threads
2411  * exit by calling sched_exit_thread() and sched_throw() themselves.
2412  */
2413 void
2414 sched_rem(struct thread *td)
2415 {
2416  struct tdq *tdq;
2417 
2418  KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem",
2419  "prio:%d", td->td_priority);
2420  SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL);
2421  tdq = TDQ_CPU(td->td_sched->ts_cpu);
2422  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2423  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2424  KASSERT(TD_ON_RUNQ(td),
2425  ("sched_rem: thread not on run queue"));
2426  tdq_runq_rem(tdq, td);
2427  tdq_load_rem(tdq, td);
2428  TD_SET_CAN_RUN(td);
2429  if (td->td_priority == tdq->tdq_lowpri)
2430  tdq_setlowpri(tdq, NULL);
2431 }
2432 
2433 /*
2434  * Fetch cpu utilization information. Updates on demand.
2435  */
2436 fixpt_t
2437 sched_pctcpu(struct thread *td)
2438 {
2439  fixpt_t pctcpu;
2440  struct td_sched *ts;
2441 
2442  pctcpu = 0;
2443  ts = td->td_sched;
2444  if (ts == NULL)
2445  return (0);
2446 
2447  THREAD_LOCK_ASSERT(td, MA_OWNED);
2448  sched_pctcpu_update(ts, TD_IS_RUNNING(td));
2449  if (ts->ts_ticks) {
2450  int rtick;
2451 
2452  /* How many rtick per second ? */
2453  rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz);
2454  pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT;
2455  }
2456 
2457  return (pctcpu);
2458 }
2459 
2460 /*
2461  * Enforce affinity settings for a thread. Called after adjustments to
2462  * cpumask.
2463  */
2464 void
2465 sched_affinity(struct thread *td)
2466 {
2467 #ifdef SMP
2468  struct td_sched *ts;
2469 
2470  THREAD_LOCK_ASSERT(td, MA_OWNED);
2471  ts = td->td_sched;
2472  if (THREAD_CAN_SCHED(td, ts->ts_cpu))
2473  return;
2474  if (TD_ON_RUNQ(td)) {
2475  sched_rem(td);
2476  sched_add(td, SRQ_BORING);
2477  return;
2478  }
2479  if (!TD_IS_RUNNING(td))
2480  return;
2481  /*
2482  * Force a switch before returning to userspace. If the
2483  * target thread is not running locally send an ipi to force
2484  * the issue.
2485  */
2486  td->td_flags |= TDF_NEEDRESCHED;
2487  if (td != curthread)
2488  ipi_cpu(ts->ts_cpu, IPI_PREEMPT);
2489 #endif
2490 }
2491 
2492 /*
2493  * Bind a thread to a target cpu.
2494  */
2495 void
2496 sched_bind(struct thread *td, int cpu)
2497 {
2498  struct td_sched *ts;
2499 
2500  THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED);
2501  KASSERT(td == curthread, ("sched_bind: can only bind curthread"));
2502  ts = td->td_sched;
2503  if (ts->ts_flags & TSF_BOUND)
2504  sched_unbind(td);
2505  KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td));
2506  ts->ts_flags |= TSF_BOUND;
2507  sched_pin();
2508  if (PCPU_GET(cpuid) == cpu)
2509  return;
2510  ts->ts_cpu = cpu;
2511  /* When we return from mi_switch we'll be on the correct cpu. */
2512  mi_switch(SW_VOL, NULL);
2513 }
2514 
2515 /*
2516  * Release a bound thread.
2517  */
2518 void
2519 sched_unbind(struct thread *td)
2520 {
2521  struct td_sched *ts;
2522 
2523  THREAD_LOCK_ASSERT(td, MA_OWNED);
2524  KASSERT(td == curthread, ("sched_unbind: can only bind curthread"));
2525  ts = td->td_sched;
2526  if ((ts->ts_flags & TSF_BOUND) == 0)
2527  return;
2528  ts->ts_flags &= ~TSF_BOUND;
2529  sched_unpin();
2530 }
2531 
2532 int
2533 sched_is_bound(struct thread *td)
2534 {
2535  THREAD_LOCK_ASSERT(td, MA_OWNED);
2536  return (td->td_sched->ts_flags & TSF_BOUND);
2537 }
2538 
2539 /*
2540  * Basic yield call.
2541  */
2542 void
2543 sched_relinquish(struct thread *td)
2544 {
2545  thread_lock(td);
2546  mi_switch(SW_VOL | SWT_RELINQUISH, NULL);
2547  thread_unlock(td);
2548 }
2549 
2550 /*
2551  * Return the total system load.
2552  */
2553 int
2555 {
2556 #ifdef SMP
2557  int total;
2558  int i;
2559 
2560  total = 0;
2561  CPU_FOREACH(i)
2562  total += TDQ_CPU(i)->tdq_sysload;
2563  return (total);
2564 #else
2565  return (TDQ_SELF()->tdq_sysload);
2566 #endif
2567 }
2568 
2569 int
2571 {
2572  return (sizeof(struct proc));
2573 }
2574 
2575 int
2577 {
2578  return (sizeof(struct thread) + sizeof(struct td_sched));
2579 }
2580 
2581 #ifdef SMP
2582 #define TDQ_IDLESPIN(tdq) \
2583  ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0)
2584 #else
2585 #define TDQ_IDLESPIN(tdq) 1
2586 #endif
2587 
2588 /*
2589  * The actual idle process.
2590  */
2591 void
2593 {
2594  struct thread *td;
2595  struct tdq *tdq;
2596  int oldswitchcnt, switchcnt;
2597  int i;
2598 
2599  mtx_assert(&Giant, MA_NOTOWNED);
2600  td = curthread;
2601  tdq = TDQ_SELF();
2602  THREAD_NO_SLEEPING();
2603  oldswitchcnt = -1;
2604  for (;;) {
2605  if (tdq->tdq_load) {
2606  thread_lock(td);
2607  mi_switch(SW_VOL | SWT_IDLE, NULL);
2608  thread_unlock(td);
2609  }
2610  switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2611 #ifdef SMP
2612  if (switchcnt != oldswitchcnt) {
2613  oldswitchcnt = switchcnt;
2614  if (tdq_idled(tdq) == 0)
2615  continue;
2616  }
2617  switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2618 #else
2619  oldswitchcnt = switchcnt;
2620 #endif
2621  /*
2622  * If we're switching very frequently, spin while checking
2623  * for load rather than entering a low power state that
2624  * may require an IPI. However, don't do any busy
2625  * loops while on SMT machines as this simply steals
2626  * cycles from cores doing useful work.
2627  */
2628  if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) {
2629  for (i = 0; i < sched_idlespins; i++) {
2630  if (tdq->tdq_load)
2631  break;
2632  cpu_spinwait();
2633  }
2634  }
2635 
2636  /* If there was context switch during spin, restart it. */
2637  switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2638  if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt)
2639  continue;
2640 
2641  /* Run main MD idle handler. */
2642  tdq->tdq_cpu_idle = 1;
2643  cpu_idle(switchcnt * 4 > sched_idlespinthresh);
2644  tdq->tdq_cpu_idle = 0;
2645 
2646  /*
2647  * Account thread-less hardware interrupts and
2648  * other wakeup reasons equal to context switches.
2649  */
2650  switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2651  if (switchcnt != oldswitchcnt)
2652  continue;
2653  tdq->tdq_switchcnt++;
2654  oldswitchcnt++;
2655  }
2656 }
2657 
2658 /*
2659  * A CPU is entering for the first time or a thread is exiting.
2660  */
2661 void
2662 sched_throw(struct thread *td)
2663 {
2664  struct thread *newtd;
2665  struct tdq *tdq;
2666 
2667  tdq = TDQ_SELF();
2668  if (td == NULL) {
2669  /* Correct spinlock nesting and acquire the correct lock. */
2670  TDQ_LOCK(tdq);
2671  spinlock_exit();
2672  PCPU_SET(switchtime, cpu_ticks());
2673  PCPU_SET(switchticks, ticks);
2674  } else {
2675  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2676  tdq_load_rem(tdq, td);
2677  lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object);
2678  }
2679  KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count"));
2680  newtd = choosethread();
2681  TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd;
2682  cpu_throw(td, newtd); /* doesn't return */
2683 }
2684 
2685 /*
2686  * This is called from fork_exit(). Just acquire the correct locks and
2687  * let fork do the rest of the work.
2688  */
2689 void
2690 sched_fork_exit(struct thread *td)
2691 {
2692  struct tdq *tdq;
2693  int cpuid;
2694 
2695  /*
2696  * Finish setting up thread glue so that it begins execution in a
2697  * non-nested critical section with the scheduler lock held.
2698  */
2699  cpuid = PCPU_GET(cpuid);
2700  tdq = TDQ_CPU(cpuid);
2701  if (TD_IS_IDLETHREAD(td))
2702  td->td_lock = TDQ_LOCKPTR(tdq);
2703  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2704  td->td_oncpu = cpuid;
2705  TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED);
2706  lock_profile_obtain_lock_success(
2707  &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__);
2708 }
2709 
2710 /*
2711  * Create on first use to catch odd startup conditons.
2712  */
2713 char *
2714 sched_tdname(struct thread *td)
2715 {
2716 #ifdef KTR
2717  struct td_sched *ts;
2718 
2719  ts = td->td_sched;
2720  if (ts->ts_name[0] == '\0')
2721  snprintf(ts->ts_name, sizeof(ts->ts_name),
2722  "%s tid %d", td->td_name, td->td_tid);
2723  return (ts->ts_name);
2724 #else
2725  return (td->td_name);
2726 #endif
2727 }
2728 
2729 #ifdef KTR
2730 void
2731 sched_clear_tdname(struct thread *td)
2732 {
2733  struct td_sched *ts;
2734 
2735  ts = td->td_sched;
2736  ts->ts_name[0] = '\0';
2737 }
2738 #endif
2739 
2740 #ifdef SMP
2741 
2742 /*
2743  * Build the CPU topology dump string. Is recursively called to collect
2744  * the topology tree.
2745  */
2746 static int
2747 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg,
2748  int indent)
2749 {
2750  char cpusetbuf[CPUSETBUFSIZ];
2751  int i, first;
2752 
2753  sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent,
2754  "", 1 + indent / 2, cg->cg_level);
2755  sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "",
2756  cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask));
2757  first = TRUE;
2758  for (i = 0; i < MAXCPU; i++) {
2759  if (CPU_ISSET(i, &cg->cg_mask)) {
2760  if (!first)
2761  sbuf_printf(sb, ", ");
2762  else
2763  first = FALSE;
2764  sbuf_printf(sb, "%d", i);
2765  }
2766  }
2767  sbuf_printf(sb, "</cpu>\n");
2768 
2769  if (cg->cg_flags != 0) {
2770  sbuf_printf(sb, "%*s <flags>", indent, "");
2771  if ((cg->cg_flags & CG_FLAG_HTT) != 0)
2772  sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>");
2773  if ((cg->cg_flags & CG_FLAG_THREAD) != 0)
2774  sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>");
2775  if ((cg->cg_flags & CG_FLAG_SMT) != 0)
2776  sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>");
2777  sbuf_printf(sb, "</flags>\n");
2778  }
2779 
2780  if (cg->cg_children > 0) {
2781  sbuf_printf(sb, "%*s <children>\n", indent, "");
2782  for (i = 0; i < cg->cg_children; i++)
2783  sysctl_kern_sched_topology_spec_internal(sb,
2784  &cg->cg_child[i], indent+2);
2785  sbuf_printf(sb, "%*s </children>\n", indent, "");
2786  }
2787  sbuf_printf(sb, "%*s</group>\n", indent, "");
2788  return (0);
2789 }
2790 
2791 /*
2792  * Sysctl handler for retrieving topology dump. It's a wrapper for
2793  * the recursive sysctl_kern_smp_topology_spec_internal().
2794  */
2795 static int
2796 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS)
2797 {
2798  struct sbuf *topo;
2799  int err;
2800 
2801  KASSERT(cpu_top != NULL, ("cpu_top isn't initialized"));
2802 
2803  topo = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND);
2804  if (topo == NULL)
2805  return (ENOMEM);
2806 
2807  sbuf_printf(topo, "<groups>\n");
2808  err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1);
2809  sbuf_printf(topo, "</groups>\n");
2810 
2811  if (err == 0) {
2812  sbuf_finish(topo);
2813  err = SYSCTL_OUT(req, sbuf_data(topo), sbuf_len(topo));
2814  }
2815  sbuf_delete(topo);
2816  return (err);
2817 }
2818 
2819 #endif
2820 
2821 static int
2822 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
2823 {
2824  int error, new_val, period;
2825 
2826  period = 1000000 / realstathz;
2827  new_val = period * sched_slice;
2828  error = sysctl_handle_int(oidp, &new_val, 0, req);
2829  if (error != 0 || req->newptr == NULL)
2830  return (error);
2831  if (new_val <= 0)
2832  return (EINVAL);
2833  sched_slice = imax(1, (new_val + period / 2) / period);
2834  sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR;
2835  hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
2836  realstathz);
2837  return (0);
2838 }
2839 
2840 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler");
2841 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0,
2842  "Scheduler name");
2843 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW,
2844  NULL, 0, sysctl_kern_quantum, "I",
2845  "Quantum for timeshare threads in microseconds");
2846 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
2847  "Quantum for timeshare threads in stathz ticks");
2848 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0,
2849  "Interactivity score threshold");
2850 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW,
2851  &preempt_thresh, 0,
2852  "Maximal (lowest) priority for preemption");
2853 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0,
2854  "Assign static kernel priorities to sleeping threads");
2855 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0,
2856  "Number of times idle thread will spin waiting for new work");
2857 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW,
2859  "Threshold before we will permit idle thread spinning");
2860 #ifdef SMP
2861 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0,
2862  "Number of hz ticks to keep thread affinity for");
2863 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0,
2864  "Enables the long-term load balancer");
2865 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW,
2866  &balance_interval, 0,
2867  "Average period in stathz ticks to run the long-term balancer");
2868 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0,
2869  "Attempts to steal work from other cores before idling");
2870 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0,
2871  "Minimum load on remote CPU before we'll steal");
2872 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING |
2873  CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A",
2874  "XML dump of detected CPU topology");
2875 #endif
2876 
2877 /* ps compat. All cpu percentages from ULE are weighted. */
2878 static int ccpu = 0;
2879 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");