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 271713 2014-09-17 17:43:32Z 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 
1041  /*
1042  * Make sure that our caller's earlier update to tdq_load is
1043  * globally visible before we read tdq_cpu_idle. Idle thread
1044  * accesses both of them without locks, and the order is important.
1045  */
1046  mb();
1047 
1048  if (TD_IS_IDLETHREAD(ctd)) {
1049  /*
1050  * If the MD code has an idle wakeup routine try that before
1051  * falling back to IPI.
1052  */
1053  if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu))
1054  return;
1055  }
1056  tdq->tdq_ipipending = 1;
1057  ipi_cpu(cpu, IPI_PREEMPT);
1058 }
1059 
1060 /*
1061  * Steals load from a timeshare queue. Honors the rotating queue head
1062  * index.
1063  */
1064 static struct thread *
1065 runq_steal_from(struct runq *rq, int cpu, u_char start)
1066 {
1067  struct rqbits *rqb;
1068  struct rqhead *rqh;
1069  struct thread *td, *first;
1070  int bit;
1071  int i;
1072 
1073  rqb = &rq->rq_status;
1074  bit = start & (RQB_BPW -1);
1075  first = NULL;
1076 again:
1077  for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) {
1078  if (rqb->rqb_bits[i] == 0)
1079  continue;
1080  if (bit == 0)
1081  bit = RQB_FFS(rqb->rqb_bits[i]);
1082  for (; bit < RQB_BPW; bit++) {
1083  if ((rqb->rqb_bits[i] & (1ul << bit)) == 0)
1084  continue;
1085  rqh = &rq->rq_queues[bit + (i << RQB_L2BPW)];
1086  TAILQ_FOREACH(td, rqh, td_runq) {
1087  if (first && THREAD_CAN_MIGRATE(td) &&
1088  THREAD_CAN_SCHED(td, cpu))
1089  return (td);
1090  first = td;
1091  }
1092  }
1093  }
1094  if (start != 0) {
1095  start = 0;
1096  goto again;
1097  }
1098 
1099  if (first && THREAD_CAN_MIGRATE(first) &&
1100  THREAD_CAN_SCHED(first, cpu))
1101  return (first);
1102  return (NULL);
1103 }
1104 
1105 /*
1106  * Steals load from a standard linear queue.
1107  */
1108 static struct thread *
1109 runq_steal(struct runq *rq, int cpu)
1110 {
1111  struct rqhead *rqh;
1112  struct rqbits *rqb;
1113  struct thread *td;
1114  int word;
1115  int bit;
1116 
1117  rqb = &rq->rq_status;
1118  for (word = 0; word < RQB_LEN; word++) {
1119  if (rqb->rqb_bits[word] == 0)
1120  continue;
1121  for (bit = 0; bit < RQB_BPW; bit++) {
1122  if ((rqb->rqb_bits[word] & (1ul << bit)) == 0)
1123  continue;
1124  rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)];
1125  TAILQ_FOREACH(td, rqh, td_runq)
1126  if (THREAD_CAN_MIGRATE(td) &&
1127  THREAD_CAN_SCHED(td, cpu))
1128  return (td);
1129  }
1130  }
1131  return (NULL);
1132 }
1133 
1134 /*
1135  * Attempt to steal a thread in priority order from a thread queue.
1136  */
1137 static struct thread *
1138 tdq_steal(struct tdq *tdq, int cpu)
1139 {
1140  struct thread *td;
1141 
1142  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
1143  if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL)
1144  return (td);
1145  if ((td = runq_steal_from(&tdq->tdq_timeshare,
1146  cpu, tdq->tdq_ridx)) != NULL)
1147  return (td);
1148  return (runq_steal(&tdq->tdq_idle, cpu));
1149 }
1150 
1151 /*
1152  * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the
1153  * current lock and returns with the assigned queue locked.
1154  */
1155 static inline struct tdq *
1156 sched_setcpu(struct thread *td, int cpu, int flags)
1157 {
1158 
1159  struct tdq *tdq;
1160 
1161  THREAD_LOCK_ASSERT(td, MA_OWNED);
1162  tdq = TDQ_CPU(cpu);
1163  td->td_sched->ts_cpu = cpu;
1164  /*
1165  * If the lock matches just return the queue.
1166  */
1167  if (td->td_lock == TDQ_LOCKPTR(tdq))
1168  return (tdq);
1169 #ifdef notyet
1170  /*
1171  * If the thread isn't running its lockptr is a
1172  * turnstile or a sleepqueue. We can just lock_set without
1173  * blocking.
1174  */
1175  if (TD_CAN_RUN(td)) {
1176  TDQ_LOCK(tdq);
1177  thread_lock_set(td, TDQ_LOCKPTR(tdq));
1178  return (tdq);
1179  }
1180 #endif
1181  /*
1182  * The hard case, migration, we need to block the thread first to
1183  * prevent order reversals with other cpus locks.
1184  */
1185  spinlock_enter();
1186  thread_lock_block(td);
1187  TDQ_LOCK(tdq);
1188  thread_lock_unblock(td, TDQ_LOCKPTR(tdq));
1189  spinlock_exit();
1190  return (tdq);
1191 }
1192 
1193 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding");
1194 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity");
1195 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity");
1196 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load");
1197 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu");
1198 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration");
1199 
1200 static int
1201 sched_pickcpu(struct thread *td, int flags)
1202 {
1203  struct cpu_group *cg, *ccg;
1204  struct td_sched *ts;
1205  struct tdq *tdq;
1206  cpuset_t mask;
1207  int cpu, pri, self;
1208 
1209  self = PCPU_GET(cpuid);
1210  ts = td->td_sched;
1211  if (smp_started == 0)
1212  return (self);
1213  /*
1214  * Don't migrate a running thread from sched_switch().
1215  */
1216  if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td))
1217  return (ts->ts_cpu);
1218  /*
1219  * Prefer to run interrupt threads on the processors that generate
1220  * the interrupt.
1221  */
1222  pri = td->td_priority;
1223  if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) &&
1224  curthread->td_intr_nesting_level && ts->ts_cpu != self) {
1225  SCHED_STAT_INC(pickcpu_intrbind);
1226  ts->ts_cpu = self;
1227  if (TDQ_CPU(self)->tdq_lowpri > pri) {
1228  SCHED_STAT_INC(pickcpu_affinity);
1229  return (ts->ts_cpu);
1230  }
1231  }
1232  /*
1233  * If the thread can run on the last cpu and the affinity has not
1234  * expired or it is idle run it there.
1235  */
1236  tdq = TDQ_CPU(ts->ts_cpu);
1237  cg = tdq->tdq_cg;
1238  if (THREAD_CAN_SCHED(td, ts->ts_cpu) &&
1239  tdq->tdq_lowpri >= PRI_MIN_IDLE &&
1240  SCHED_AFFINITY(ts, CG_SHARE_L2)) {
1241  if (cg->cg_flags & CG_FLAG_THREAD) {
1242  CPUSET_FOREACH(cpu, cg->cg_mask) {
1243  if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE)
1244  break;
1245  }
1246  } else
1247  cpu = INT_MAX;
1248  if (cpu > mp_maxid) {
1249  SCHED_STAT_INC(pickcpu_idle_affinity);
1250  return (ts->ts_cpu);
1251  }
1252  }
1253  /*
1254  * Search for the last level cache CPU group in the tree.
1255  * Skip caches with expired affinity time and SMT groups.
1256  * Affinity to higher level caches will be handled less aggressively.
1257  */
1258  for (ccg = NULL; cg != NULL; cg = cg->cg_parent) {
1259  if (cg->cg_flags & CG_FLAG_THREAD)
1260  continue;
1261  if (!SCHED_AFFINITY(ts, cg->cg_level))
1262  continue;
1263  ccg = cg;
1264  }
1265  if (ccg != NULL)
1266  cg = ccg;
1267  cpu = -1;
1268  /* Search the group for the less loaded idle CPU we can run now. */
1269  mask = td->td_cpuset->cs_mask;
1270  if (cg != NULL && cg != cpu_top &&
1271  CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0)
1272  cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE),
1273  INT_MAX, ts->ts_cpu);
1274  /* Search globally for the less loaded CPU we can run now. */
1275  if (cpu == -1)
1276  cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu);
1277  /* Search globally for the less loaded CPU. */
1278  if (cpu == -1)
1279  cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu);
1280  KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu."));
1281  /*
1282  * Compare the lowest loaded cpu to current cpu.
1283  */
1284  if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri &&
1285  TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE &&
1286  TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) {
1287  SCHED_STAT_INC(pickcpu_local);
1288  cpu = self;
1289  } else
1290  SCHED_STAT_INC(pickcpu_lowest);
1291  if (cpu != ts->ts_cpu)
1292  SCHED_STAT_INC(pickcpu_migration);
1293  return (cpu);
1294 }
1295 #endif
1296 
1297 /*
1298  * Pick the highest priority task we have and return it.
1299  */
1300 static struct thread *
1301 tdq_choose(struct tdq *tdq)
1302 {
1303  struct thread *td;
1304 
1305  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
1306  td = runq_choose(&tdq->tdq_realtime);
1307  if (td != NULL)
1308  return (td);
1309  td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx);
1310  if (td != NULL) {
1311  KASSERT(td->td_priority >= PRI_MIN_BATCH,
1312  ("tdq_choose: Invalid priority on timeshare queue %d",
1313  td->td_priority));
1314  return (td);
1315  }
1316  td = runq_choose(&tdq->tdq_idle);
1317  if (td != NULL) {
1318  KASSERT(td->td_priority >= PRI_MIN_IDLE,
1319  ("tdq_choose: Invalid priority on idle queue %d",
1320  td->td_priority));
1321  return (td);
1322  }
1323 
1324  return (NULL);
1325 }
1326 
1327 /*
1328  * Initialize a thread queue.
1329  */
1330 static void
1331 tdq_setup(struct tdq *tdq)
1332 {
1333 
1334  if (bootverbose)
1335  printf("ULE: setup cpu %d\n", TDQ_ID(tdq));
1336  runq_init(&tdq->tdq_realtime);
1337  runq_init(&tdq->tdq_timeshare);
1338  runq_init(&tdq->tdq_idle);
1339  snprintf(tdq->tdq_name, sizeof(tdq->tdq_name),
1340  "sched lock %d", (int)TDQ_ID(tdq));
1341  mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock",
1342  MTX_SPIN | MTX_RECURSE);
1343 #ifdef KTR
1344  snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname),
1345  "CPU %d load", (int)TDQ_ID(tdq));
1346 #endif
1347 }
1348 
1349 #ifdef SMP
1350 static void
1351 sched_setup_smp(void)
1352 {
1353  struct tdq *tdq;
1354  int i;
1355 
1356  cpu_top = smp_topo();
1357  CPU_FOREACH(i) {
1358  tdq = TDQ_CPU(i);
1359  tdq_setup(tdq);
1360  tdq->tdq_cg = smp_topo_find(cpu_top, i);
1361  if (tdq->tdq_cg == NULL)
1362  panic("Can't find cpu group for %d\n", i);
1363  }
1364  balance_tdq = TDQ_SELF();
1365  sched_balance();
1366 }
1367 #endif
1368 
1369 /*
1370  * Setup the thread queues and initialize the topology based on MD
1371  * information.
1372  */
1373 static void
1375 {
1376  struct tdq *tdq;
1377 
1378  tdq = TDQ_SELF();
1379 #ifdef SMP
1380  sched_setup_smp();
1381 #else
1382  tdq_setup(tdq);
1383 #endif
1384 
1385  /* Add thread0's load since it's running. */
1386  TDQ_LOCK(tdq);
1387  thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF());
1388  tdq_load_add(tdq, &thread0);
1389  tdq->tdq_lowpri = thread0.td_priority;
1390  TDQ_UNLOCK(tdq);
1391 }
1392 
1393 /*
1394  * This routine determines time constants after stathz and hz are setup.
1395  */
1396 /* ARGSUSED */
1397 static void
1399 {
1400  int incr;
1401 
1402  realstathz = stathz ? stathz : hz;
1405  hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
1406  realstathz);
1407 
1408  /*
1409  * tickincr is shifted out by 10 to avoid rounding errors due to
1410  * hz not being evenly divisible by stathz on all platforms.
1411  */
1412  incr = (hz << SCHED_TICK_SHIFT) / realstathz;
1413  /*
1414  * This does not work for values of stathz that are more than
1415  * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen.
1416  */
1417  if (incr == 0)
1418  incr = 1;
1419  tickincr = incr;
1420 #ifdef SMP
1421  /*
1422  * Set the default balance interval now that we know
1423  * what realstathz is.
1424  */
1425  balance_interval = realstathz;
1426  affinity = SCHED_AFFINITY_DEFAULT;
1427 #endif
1428  if (sched_idlespinthresh < 0)
1429  sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz;
1430 }
1431 
1432 
1433 /*
1434  * This is the core of the interactivity algorithm. Determines a score based
1435  * on past behavior. It is the ratio of sleep time to run time scaled to
1436  * a [0, 100] integer. This is the voluntary sleep time of a process, which
1437  * differs from the cpu usage because it does not account for time spent
1438  * waiting on a run-queue. Would be prettier if we had floating point.
1439  */
1440 static int
1441 sched_interact_score(struct thread *td)
1442 {
1443  struct td_sched *ts;
1444  int div;
1445 
1446  ts = td->td_sched;
1447  /*
1448  * The score is only needed if this is likely to be an interactive
1449  * task. Don't go through the expense of computing it if there's
1450  * no chance.
1451  */
1453  ts->ts_runtime >= ts->ts_slptime)
1454  return (SCHED_INTERACT_HALF);
1455 
1456  if (ts->ts_runtime > ts->ts_slptime) {
1457  div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF);
1458  return (SCHED_INTERACT_HALF +
1459  (SCHED_INTERACT_HALF - (ts->ts_slptime / div)));
1460  }
1461  if (ts->ts_slptime > ts->ts_runtime) {
1462  div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF);
1463  return (ts->ts_runtime / div);
1464  }
1465  /* runtime == slptime */
1466  if (ts->ts_runtime)
1467  return (SCHED_INTERACT_HALF);
1468 
1469  /*
1470  * This can happen if slptime and runtime are 0.
1471  */
1472  return (0);
1473 
1474 }
1475 
1476 /*
1477  * Scale the scheduling priority according to the "interactivity" of this
1478  * process.
1479  */
1480 static void
1481 sched_priority(struct thread *td)
1482 {
1483  int score;
1484  int pri;
1485 
1486  if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE)
1487  return;
1488  /*
1489  * If the score is interactive we place the thread in the realtime
1490  * queue with a priority that is less than kernel and interrupt
1491  * priorities. These threads are not subject to nice restrictions.
1492  *
1493  * Scores greater than this are placed on the normal timeshare queue
1494  * where the priority is partially decided by the most recent cpu
1495  * utilization and the rest is decided by nice value.
1496  *
1497  * The nice value of the process has a linear effect on the calculated
1498  * score. Negative nice values make it easier for a thread to be
1499  * considered interactive.
1500  */
1501  score = imax(0, sched_interact_score(td) + td->td_proc->p_nice);
1502  if (score < sched_interact) {
1503  pri = PRI_MIN_INTERACT;
1504  pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) /
1505  sched_interact) * score;
1506  KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT,
1507  ("sched_priority: invalid interactive priority %d score %d",
1508  pri, score));
1509  } else {
1510  pri = SCHED_PRI_MIN;
1511  if (td->td_sched->ts_ticks)
1512  pri += min(SCHED_PRI_TICKS(td->td_sched),
1513  SCHED_PRI_RANGE - 1);
1514  pri += SCHED_PRI_NICE(td->td_proc->p_nice);
1515  KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH,
1516  ("sched_priority: invalid priority %d: nice %d, "
1517  "ticks %d ftick %d ltick %d tick pri %d",
1518  pri, td->td_proc->p_nice, td->td_sched->ts_ticks,
1519  td->td_sched->ts_ftick, td->td_sched->ts_ltick,
1520  SCHED_PRI_TICKS(td->td_sched)));
1521  }
1522  sched_user_prio(td, pri);
1523 
1524  return;
1525 }
1526 
1527 /*
1528  * This routine enforces a maximum limit on the amount of scheduling history
1529  * kept. It is called after either the slptime or runtime is adjusted. This
1530  * function is ugly due to integer math.
1531  */
1532 static void
1533 sched_interact_update(struct thread *td)
1534 {
1535  struct td_sched *ts;
1536  u_int sum;
1537 
1538  ts = td->td_sched;
1539  sum = ts->ts_runtime + ts->ts_slptime;
1540  if (sum < SCHED_SLP_RUN_MAX)
1541  return;
1542  /*
1543  * This only happens from two places:
1544  * 1) We have added an unusual amount of run time from fork_exit.
1545  * 2) We have added an unusual amount of sleep time from sched_sleep().
1546  */
1547  if (sum > SCHED_SLP_RUN_MAX * 2) {
1548  if (ts->ts_runtime > ts->ts_slptime) {
1550  ts->ts_slptime = 1;
1551  } else {
1553  ts->ts_runtime = 1;
1554  }
1555  return;
1556  }
1557  /*
1558  * If we have exceeded by more than 1/5th then the algorithm below
1559  * will not bring us back into range. Dividing by two here forces
1560  * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX]
1561  */
1562  if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) {
1563  ts->ts_runtime /= 2;
1564  ts->ts_slptime /= 2;
1565  return;
1566  }
1567  ts->ts_runtime = (ts->ts_runtime / 5) * 4;
1568  ts->ts_slptime = (ts->ts_slptime / 5) * 4;
1569 }
1570 
1571 /*
1572  * Scale back the interactivity history when a child thread is created. The
1573  * history is inherited from the parent but the thread may behave totally
1574  * differently. For example, a shell spawning a compiler process. We want
1575  * to learn that the compiler is behaving badly very quickly.
1576  */
1577 static void
1578 sched_interact_fork(struct thread *td)
1579 {
1580  int ratio;
1581  int sum;
1582 
1583  sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime;
1584  if (sum > SCHED_SLP_RUN_FORK) {
1585  ratio = sum / SCHED_SLP_RUN_FORK;
1586  td->td_sched->ts_runtime /= ratio;
1587  td->td_sched->ts_slptime /= ratio;
1588  }
1589 }
1590 
1591 /*
1592  * Called from proc0_init() to setup the scheduler fields.
1593  */
1594 void
1596 {
1597 
1598  /*
1599  * Set up the scheduler specific parts of proc0.
1600  */
1601  proc0.p_sched = NULL; /* XXX */
1602  thread0.td_sched = &td_sched0;
1605  td_sched0.ts_slice = 0;
1606 }
1607 
1608 /*
1609  * This is only somewhat accurate since given many processes of the same
1610  * priority they will switch when their slices run out, which will be
1611  * at most sched_slice stathz ticks.
1612  */
1613 int
1615 {
1616 
1617  /* Convert sched_slice from stathz to hz. */
1618  return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz));
1619 }
1620 
1621 /*
1622  * Update the percent cpu tracking information when it is requested or
1623  * the total history exceeds the maximum. We keep a sliding history of
1624  * tick counts that slowly decays. This is less precise than the 4BSD
1625  * mechanism since it happens with less regular and frequent events.
1626  */
1627 static void
1628 sched_pctcpu_update(struct td_sched *ts, int run)
1629 {
1630  int t = ticks;
1631 
1632  if (t - ts->ts_ltick >= SCHED_TICK_TARG) {
1633  ts->ts_ticks = 0;
1634  ts->ts_ftick = t - SCHED_TICK_TARG;
1635  } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) {
1636  ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) *
1637  (ts->ts_ltick - (t - SCHED_TICK_TARG));
1638  ts->ts_ftick = t - SCHED_TICK_TARG;
1639  }
1640  if (run)
1641  ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT;
1642  ts->ts_ltick = t;
1643 }
1644 
1645 /*
1646  * Adjust the priority of a thread. Move it to the appropriate run-queue
1647  * if necessary. This is the back-end for several priority related
1648  * functions.
1649  */
1650 static void
1651 sched_thread_priority(struct thread *td, u_char prio)
1652 {
1653  struct td_sched *ts;
1654  struct tdq *tdq;
1655  int oldpri;
1656 
1657  KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio",
1658  "prio:%d", td->td_priority, "new prio:%d", prio,
1659  KTR_ATTR_LINKED, sched_tdname(curthread));
1660  SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio);
1661  if (td != curthread && prio < td->td_priority) {
1662  KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread),
1663  "lend prio", "prio:%d", td->td_priority, "new prio:%d",
1664  prio, KTR_ATTR_LINKED, sched_tdname(td));
1665  SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio,
1666  curthread);
1667  }
1668  ts = td->td_sched;
1669  THREAD_LOCK_ASSERT(td, MA_OWNED);
1670  if (td->td_priority == prio)
1671  return;
1672  /*
1673  * If the priority has been elevated due to priority
1674  * propagation, we may have to move ourselves to a new
1675  * queue. This could be optimized to not re-add in some
1676  * cases.
1677  */
1678  if (TD_ON_RUNQ(td) && prio < td->td_priority) {
1679  sched_rem(td);
1680  td->td_priority = prio;
1681  sched_add(td, SRQ_BORROWING);
1682  return;
1683  }
1684  /*
1685  * If the thread is currently running we may have to adjust the lowpri
1686  * information so other cpus are aware of our current priority.
1687  */
1688  if (TD_IS_RUNNING(td)) {
1689  tdq = TDQ_CPU(ts->ts_cpu);
1690  oldpri = td->td_priority;
1691  td->td_priority = prio;
1692  if (prio < tdq->tdq_lowpri)
1693  tdq->tdq_lowpri = prio;
1694  else if (tdq->tdq_lowpri == oldpri)
1695  tdq_setlowpri(tdq, td);
1696  return;
1697  }
1698  td->td_priority = prio;
1699 }
1700 
1701 /*
1702  * Update a thread's priority when it is lent another thread's
1703  * priority.
1704  */
1705 void
1706 sched_lend_prio(struct thread *td, u_char prio)
1707 {
1708 
1709  td->td_flags |= TDF_BORROWING;
1710  sched_thread_priority(td, prio);
1711 }
1712 
1713 /*
1714  * Restore a thread's priority when priority propagation is
1715  * over. The prio argument is the minimum priority the thread
1716  * needs to have to satisfy other possible priority lending
1717  * requests. If the thread's regular priority is less
1718  * important than prio, the thread will keep a priority boost
1719  * of prio.
1720  */
1721 void
1722 sched_unlend_prio(struct thread *td, u_char prio)
1723 {
1724  u_char base_pri;
1725 
1726  if (td->td_base_pri >= PRI_MIN_TIMESHARE &&
1727  td->td_base_pri <= PRI_MAX_TIMESHARE)
1728  base_pri = td->td_user_pri;
1729  else
1730  base_pri = td->td_base_pri;
1731  if (prio >= base_pri) {
1732  td->td_flags &= ~TDF_BORROWING;
1733  sched_thread_priority(td, base_pri);
1734  } else
1735  sched_lend_prio(td, prio);
1736 }
1737 
1738 /*
1739  * Standard entry for setting the priority to an absolute value.
1740  */
1741 void
1742 sched_prio(struct thread *td, u_char prio)
1743 {
1744  u_char oldprio;
1745 
1746  /* First, update the base priority. */
1747  td->td_base_pri = prio;
1748 
1749  /*
1750  * If the thread is borrowing another thread's priority, don't
1751  * ever lower the priority.
1752  */
1753  if (td->td_flags & TDF_BORROWING && td->td_priority < prio)
1754  return;
1755 
1756  /* Change the real priority. */
1757  oldprio = td->td_priority;
1758  sched_thread_priority(td, prio);
1759 
1760  /*
1761  * If the thread is on a turnstile, then let the turnstile update
1762  * its state.
1763  */
1764  if (TD_ON_LOCK(td) && oldprio != prio)
1765  turnstile_adjust(td, oldprio);
1766 }
1767 
1768 /*
1769  * Set the base user priority, does not effect current running priority.
1770  */
1771 void
1772 sched_user_prio(struct thread *td, u_char prio)
1773 {
1774 
1775  td->td_base_user_pri = prio;
1776  if (td->td_lend_user_pri <= prio)
1777  return;
1778  td->td_user_pri = prio;
1779 }
1780 
1781 void
1782 sched_lend_user_prio(struct thread *td, u_char prio)
1783 {
1784 
1785  THREAD_LOCK_ASSERT(td, MA_OWNED);
1786  td->td_lend_user_pri = prio;
1787  td->td_user_pri = min(prio, td->td_base_user_pri);
1788  if (td->td_priority > td->td_user_pri)
1789  sched_prio(td, td->td_user_pri);
1790  else if (td->td_priority != td->td_user_pri)
1791  td->td_flags |= TDF_NEEDRESCHED;
1792 }
1793 
1794 /*
1795  * Handle migration from sched_switch(). This happens only for
1796  * cpu binding.
1797  */
1798 static struct mtx *
1799 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags)
1800 {
1801  struct tdq *tdn;
1802 
1803  tdn = TDQ_CPU(td->td_sched->ts_cpu);
1804 #ifdef SMP
1805  tdq_load_rem(tdq, td);
1806  /*
1807  * Do the lock dance required to avoid LOR. We grab an extra
1808  * spinlock nesting to prevent preemption while we're
1809  * not holding either run-queue lock.
1810  */
1811  spinlock_enter();
1812  thread_lock_block(td); /* This releases the lock on tdq. */
1813 
1814  /*
1815  * Acquire both run-queue locks before placing the thread on the new
1816  * run-queue to avoid deadlocks created by placing a thread with a
1817  * blocked lock on the run-queue of a remote processor. The deadlock
1818  * occurs when a third processor attempts to lock the two queues in
1819  * question while the target processor is spinning with its own
1820  * run-queue lock held while waiting for the blocked lock to clear.
1821  */
1822  tdq_lock_pair(tdn, tdq);
1823  tdq_add(tdn, td, flags);
1824  tdq_notify(tdn, td);
1825  TDQ_UNLOCK(tdn);
1826  spinlock_exit();
1827 #endif
1828  return (TDQ_LOCKPTR(tdn));
1829 }
1830 
1831 /*
1832  * Variadic version of thread_lock_unblock() that does not assume td_lock
1833  * is blocked.
1834  */
1835 static inline void
1836 thread_unblock_switch(struct thread *td, struct mtx *mtx)
1837 {
1838  atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock,
1839  (uintptr_t)mtx);
1840 }
1841 
1842 /*
1843  * Switch threads. This function has to handle threads coming in while
1844  * blocked for some reason, running, or idle. It also must deal with
1845  * migrating a thread from one queue to another as running threads may
1846  * be assigned elsewhere via binding.
1847  */
1848 void
1849 sched_switch(struct thread *td, struct thread *newtd, int flags)
1850 {
1851  struct tdq *tdq;
1852  struct td_sched *ts;
1853  struct mtx *mtx;
1854  int srqflag;
1855  int cpuid, preempted;
1856 
1857  THREAD_LOCK_ASSERT(td, MA_OWNED);
1858  KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument"));
1859 
1860  cpuid = PCPU_GET(cpuid);
1861  tdq = TDQ_CPU(cpuid);
1862  ts = td->td_sched;
1863  mtx = td->td_lock;
1864  sched_pctcpu_update(ts, 1);
1865  ts->ts_rltick = ticks;
1866  td->td_lastcpu = td->td_oncpu;
1867  td->td_oncpu = NOCPU;
1868  preempted = !((td->td_flags & TDF_SLICEEND) ||
1869  (flags & SWT_RELINQUISH));
1870  td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND);
1871  td->td_owepreempt = 0;
1872  if (!TD_IS_IDLETHREAD(td))
1873  tdq->tdq_switchcnt++;
1874  /*
1875  * The lock pointer in an idle thread should never change. Reset it
1876  * to CAN_RUN as well.
1877  */
1878  if (TD_IS_IDLETHREAD(td)) {
1879  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1880  TD_SET_CAN_RUN(td);
1881  } else if (TD_IS_RUNNING(td)) {
1882  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1883  srqflag = preempted ?
1884  SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
1885  SRQ_OURSELF|SRQ_YIELDING;
1886 #ifdef SMP
1887  if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu))
1888  ts->ts_cpu = sched_pickcpu(td, 0);
1889 #endif
1890  if (ts->ts_cpu == cpuid)
1891  tdq_runq_add(tdq, td, srqflag);
1892  else {
1893  KASSERT(THREAD_CAN_MIGRATE(td) ||
1894  (ts->ts_flags & TSF_BOUND) != 0,
1895  ("Thread %p shouldn't migrate", td));
1896  mtx = sched_switch_migrate(tdq, td, srqflag);
1897  }
1898  } else {
1899  /* This thread must be going to sleep. */
1900  TDQ_LOCK(tdq);
1901  mtx = thread_lock_block(td);
1902  tdq_load_rem(tdq, td);
1903  }
1904  /*
1905  * We enter here with the thread blocked and assigned to the
1906  * appropriate cpu run-queue or sleep-queue and with the current
1907  * thread-queue locked.
1908  */
1909  TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED);
1910  newtd = choosethread();
1911  /*
1912  * Call the MD code to switch contexts if necessary.
1913  */
1914  if (td != newtd) {
1915 #ifdef HWPMC_HOOKS
1916  if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1917  PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
1918 #endif
1919  SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc);
1920  lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object);
1921  TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd;
1922  sched_pctcpu_update(newtd->td_sched, 0);
1923 
1924 #ifdef KDTRACE_HOOKS
1925  /*
1926  * If DTrace has set the active vtime enum to anything
1927  * other than INACTIVE (0), then it should have set the
1928  * function to call.
1929  */
1930  if (dtrace_vtime_active)
1931  (*dtrace_vtime_switch_func)(newtd);
1932 #endif
1933 
1934  cpu_switch(td, newtd, mtx);
1935  /*
1936  * We may return from cpu_switch on a different cpu. However,
1937  * we always return with td_lock pointing to the current cpu's
1938  * run queue lock.
1939  */
1940  cpuid = PCPU_GET(cpuid);
1941  tdq = TDQ_CPU(cpuid);
1942  lock_profile_obtain_lock_success(
1943  &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__);
1944 
1945  SDT_PROBE0(sched, , , on__cpu);
1946 #ifdef HWPMC_HOOKS
1947  if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1948  PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
1949 #endif
1950  } else {
1951  thread_unblock_switch(td, mtx);
1952  SDT_PROBE0(sched, , , remain__cpu);
1953  }
1954  /*
1955  * Assert that all went well and return.
1956  */
1957  TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED);
1958  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1959  td->td_oncpu = cpuid;
1960 }
1961 
1962 /*
1963  * Adjust thread priorities as a result of a nice request.
1964  */
1965 void
1966 sched_nice(struct proc *p, int nice)
1967 {
1968  struct thread *td;
1969 
1970  PROC_LOCK_ASSERT(p, MA_OWNED);
1971 
1972  p->p_nice = nice;
1973  FOREACH_THREAD_IN_PROC(p, td) {
1974  thread_lock(td);
1975  sched_priority(td);
1976  sched_prio(td, td->td_base_user_pri);
1977  thread_unlock(td);
1978  }
1979 }
1980 
1981 /*
1982  * Record the sleep time for the interactivity scorer.
1983  */
1984 void
1985 sched_sleep(struct thread *td, int prio)
1986 {
1987 
1988  THREAD_LOCK_ASSERT(td, MA_OWNED);
1989 
1990  td->td_slptick = ticks;
1991  if (TD_IS_SUSPENDED(td) || prio >= PSOCK)
1992  td->td_flags |= TDF_CANSWAP;
1993  if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE)
1994  return;
1995  if (static_boost == 1 && prio)
1996  sched_prio(td, prio);
1997  else if (static_boost && td->td_priority > static_boost)
1998  sched_prio(td, static_boost);
1999 }
2000 
2001 /*
2002  * Schedule a thread to resume execution and record how long it voluntarily
2003  * slept. We also update the pctcpu, interactivity, and priority.
2004  */
2005 void
2006 sched_wakeup(struct thread *td)
2007 {
2008  struct td_sched *ts;
2009  int slptick;
2010 
2011  THREAD_LOCK_ASSERT(td, MA_OWNED);
2012  ts = td->td_sched;
2013  td->td_flags &= ~TDF_CANSWAP;
2014  /*
2015  * If we slept for more than a tick update our interactivity and
2016  * priority.
2017  */
2018  slptick = td->td_slptick;
2019  td->td_slptick = 0;
2020  if (slptick && slptick != ticks) {
2021  ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT;
2023  sched_pctcpu_update(ts, 0);
2024  }
2025  /*
2026  * Reset the slice value since we slept and advanced the round-robin.
2027  */
2028  ts->ts_slice = 0;
2029  sched_add(td, SRQ_BORING);
2030 }
2031 
2032 /*
2033  * Penalize the parent for creating a new child and initialize the child's
2034  * priority.
2035  */
2036 void
2037 sched_fork(struct thread *td, struct thread *child)
2038 {
2039  THREAD_LOCK_ASSERT(td, MA_OWNED);
2040  sched_pctcpu_update(td->td_sched, 1);
2041  sched_fork_thread(td, child);
2042  /*
2043  * Penalize the parent and child for forking.
2044  */
2045  sched_interact_fork(child);
2046  sched_priority(child);
2047  td->td_sched->ts_runtime += tickincr;
2049  sched_priority(td);
2050 }
2051 
2052 /*
2053  * Fork a new thread, may be within the same process.
2054  */
2055 void
2056 sched_fork_thread(struct thread *td, struct thread *child)
2057 {
2058  struct td_sched *ts;
2059  struct td_sched *ts2;
2060  struct tdq *tdq;
2061 
2062  tdq = TDQ_SELF();
2063  THREAD_LOCK_ASSERT(td, MA_OWNED);
2064  /*
2065  * Initialize child.
2066  */
2067  ts = td->td_sched;
2068  ts2 = child->td_sched;
2069  child->td_lock = TDQ_LOCKPTR(tdq);
2070  child->td_cpuset = cpuset_ref(td->td_cpuset);
2071  ts2->ts_cpu = ts->ts_cpu;
2072  ts2->ts_flags = 0;
2073  /*
2074  * Grab our parents cpu estimation information.
2075  */
2076  ts2->ts_ticks = ts->ts_ticks;
2077  ts2->ts_ltick = ts->ts_ltick;
2078  ts2->ts_ftick = ts->ts_ftick;
2079  /*
2080  * Do not inherit any borrowed priority from the parent.
2081  */
2082  child->td_priority = child->td_base_pri;
2083  /*
2084  * And update interactivity score.
2085  */
2086  ts2->ts_slptime = ts->ts_slptime;
2087  ts2->ts_runtime = ts->ts_runtime;
2088  /* Attempt to quickly learn interactivity. */
2089  ts2->ts_slice = tdq_slice(tdq) - sched_slice_min;
2090 #ifdef KTR
2091  bzero(ts2->ts_name, sizeof(ts2->ts_name));
2092 #endif
2093 }
2094 
2095 /*
2096  * Adjust the priority class of a thread.
2097  */
2098 void
2099 sched_class(struct thread *td, int class)
2100 {
2101 
2102  THREAD_LOCK_ASSERT(td, MA_OWNED);
2103  if (td->td_pri_class == class)
2104  return;
2105  td->td_pri_class = class;
2106 }
2107 
2108 /*
2109  * Return some of the child's priority and interactivity to the parent.
2110  */
2111 void
2112 sched_exit(struct proc *p, struct thread *child)
2113 {
2114  struct thread *td;
2115 
2116  KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit",
2117  "prio:%d", child->td_priority);
2118  PROC_LOCK_ASSERT(p, MA_OWNED);
2119  td = FIRST_THREAD_IN_PROC(p);
2120  sched_exit_thread(td, child);
2121 }
2122 
2123 /*
2124  * Penalize another thread for the time spent on this one. This helps to
2125  * worsen the priority and interactivity of processes which schedule batch
2126  * jobs such as make. This has little effect on the make process itself but
2127  * causes new processes spawned by it to receive worse scores immediately.
2128  */
2129 void
2130 sched_exit_thread(struct thread *td, struct thread *child)
2131 {
2132 
2133  KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit",
2134  "prio:%d", child->td_priority);
2135  /*
2136  * Give the child's runtime to the parent without returning the
2137  * sleep time as a penalty to the parent. This causes shells that
2138  * launch expensive things to mark their children as expensive.
2139  */
2140  thread_lock(td);
2141  td->td_sched->ts_runtime += child->td_sched->ts_runtime;
2143  sched_priority(td);
2144  thread_unlock(td);
2145 }
2146 
2147 void
2148 sched_preempt(struct thread *td)
2149 {
2150  struct tdq *tdq;
2151 
2152  SDT_PROBE2(sched, , , surrender, td, td->td_proc);
2153 
2154  thread_lock(td);
2155  tdq = TDQ_SELF();
2156  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2157  tdq->tdq_ipipending = 0;
2158  if (td->td_priority > tdq->tdq_lowpri) {
2159  int flags;
2160 
2161  flags = SW_INVOL | SW_PREEMPT;
2162  if (td->td_critnest > 1)
2163  td->td_owepreempt = 1;
2164  else if (TD_IS_IDLETHREAD(td))
2165  mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL);
2166  else
2167  mi_switch(flags | SWT_REMOTEPREEMPT, NULL);
2168  }
2169  thread_unlock(td);
2170 }
2171 
2172 /*
2173  * Fix priorities on return to user-space. Priorities may be elevated due
2174  * to static priorities in msleep() or similar.
2175  */
2176 void
2177 sched_userret(struct thread *td)
2178 {
2179  /*
2180  * XXX we cheat slightly on the locking here to avoid locking in
2181  * the usual case. Setting td_priority here is essentially an
2182  * incomplete workaround for not setting it properly elsewhere.
2183  * Now that some interrupt handlers are threads, not setting it
2184  * properly elsewhere can clobber it in the window between setting
2185  * it here and returning to user mode, so don't waste time setting
2186  * it perfectly here.
2187  */
2188  KASSERT((td->td_flags & TDF_BORROWING) == 0,
2189  ("thread with borrowed priority returning to userland"));
2190  if (td->td_priority != td->td_user_pri) {
2191  thread_lock(td);
2192  td->td_priority = td->td_user_pri;
2193  td->td_base_pri = td->td_user_pri;
2194  tdq_setlowpri(TDQ_SELF(), td);
2195  thread_unlock(td);
2196  }
2197 }
2198 
2199 /*
2200  * Handle a stathz tick. This is really only relevant for timeshare
2201  * threads.
2202  */
2203 void
2204 sched_clock(struct thread *td)
2205 {
2206  struct tdq *tdq;
2207  struct td_sched *ts;
2208 
2209  THREAD_LOCK_ASSERT(td, MA_OWNED);
2210  tdq = TDQ_SELF();
2211 #ifdef SMP
2212  /*
2213  * We run the long term load balancer infrequently on the first cpu.
2214  */
2215  if (balance_tdq == tdq) {
2216  if (balance_ticks && --balance_ticks == 0)
2217  sched_balance();
2218  }
2219 #endif
2220  /*
2221  * Save the old switch count so we have a record of the last ticks
2222  * activity. Initialize the new switch count based on our load.
2223  * If there is some activity seed it to reflect that.
2224  */
2225  tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt;
2226  tdq->tdq_switchcnt = tdq->tdq_load;
2227  /*
2228  * Advance the insert index once for each tick to ensure that all
2229  * threads get a chance to run.
2230  */
2231  if (tdq->tdq_idx == tdq->tdq_ridx) {
2232  tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS;
2233  if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx]))
2234  tdq->tdq_ridx = tdq->tdq_idx;
2235  }
2236  ts = td->td_sched;
2237  sched_pctcpu_update(ts, 1);
2238  if (td->td_pri_class & PRI_FIFO_BIT)
2239  return;
2240  if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) {
2241  /*
2242  * We used a tick; charge it to the thread so
2243  * that we can compute our interactivity.
2244  */
2245  td->td_sched->ts_runtime += tickincr;
2247  sched_priority(td);
2248  }
2249 
2250  /*
2251  * Force a context switch if the current thread has used up a full
2252  * time slice (default is 100ms).
2253  */
2254  if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) {
2255  ts->ts_slice = 0;
2256  td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND;
2257  }
2258 }
2259 
2260 /*
2261  * Called once per hz tick.
2262  */
2263 void
2264 sched_tick(int cnt)
2265 {
2266 
2267 }
2268 
2269 /*
2270  * Return whether the current CPU has runnable tasks. Used for in-kernel
2271  * cooperative idle threads.
2272  */
2273 int
2275 {
2276  struct tdq *tdq;
2277  int load;
2278 
2279  load = 1;
2280 
2281  tdq = TDQ_SELF();
2282  if ((curthread->td_flags & TDF_IDLETD) != 0) {
2283  if (tdq->tdq_load > 0)
2284  goto out;
2285  } else
2286  if (tdq->tdq_load - 1 > 0)
2287  goto out;
2288  load = 0;
2289 out:
2290  return (load);
2291 }
2292 
2293 /*
2294  * Choose the highest priority thread to run. The thread is removed from
2295  * the run-queue while running however the load remains. For SMP we set
2296  * the tdq in the global idle bitmask if it idles here.
2297  */
2298 struct thread *
2300 {
2301  struct thread *td;
2302  struct tdq *tdq;
2303 
2304  tdq = TDQ_SELF();
2305  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2306  td = tdq_choose(tdq);
2307  if (td) {
2308  tdq_runq_rem(tdq, td);
2309  tdq->tdq_lowpri = td->td_priority;
2310  return (td);
2311  }
2312  tdq->tdq_lowpri = PRI_MAX_IDLE;
2313  return (PCPU_GET(idlethread));
2314 }
2315 
2316 /*
2317  * Set owepreempt if necessary. Preemption never happens directly in ULE,
2318  * we always request it once we exit a critical section.
2319  */
2320 static inline void
2321 sched_setpreempt(struct thread *td)
2322 {
2323  struct thread *ctd;
2324  int cpri;
2325  int pri;
2326 
2327  THREAD_LOCK_ASSERT(curthread, MA_OWNED);
2328 
2329  ctd = curthread;
2330  pri = td->td_priority;
2331  cpri = ctd->td_priority;
2332  if (pri < cpri)
2333  ctd->td_flags |= TDF_NEEDRESCHED;
2334  if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd))
2335  return;
2336  if (!sched_shouldpreempt(pri, cpri, 0))
2337  return;
2338  ctd->td_owepreempt = 1;
2339 }
2340 
2341 /*
2342  * Add a thread to a thread queue. Select the appropriate runq and add the
2343  * thread to it. This is the internal function called when the tdq is
2344  * predetermined.
2345  */
2346 void
2347 tdq_add(struct tdq *tdq, struct thread *td, int flags)
2348 {
2349 
2350  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2351  KASSERT((td->td_inhibitors == 0),
2352  ("sched_add: trying to run inhibited thread"));
2353  KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
2354  ("sched_add: bad thread state"));
2355  KASSERT(td->td_flags & TDF_INMEM,
2356  ("sched_add: thread swapped out"));
2357 
2358  if (td->td_priority < tdq->tdq_lowpri)
2359  tdq->tdq_lowpri = td->td_priority;
2360  tdq_runq_add(tdq, td, flags);
2361  tdq_load_add(tdq, td);
2362 }
2363 
2364 /*
2365  * Select the target thread queue and add a thread to it. Request
2366  * preemption or IPI a remote processor if required.
2367  */
2368 void
2369 sched_add(struct thread *td, int flags)
2370 {
2371  struct tdq *tdq;
2372 #ifdef SMP
2373  int cpu;
2374 #endif
2375 
2376  KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
2377  "prio:%d", td->td_priority, KTR_ATTR_LINKED,
2378  sched_tdname(curthread));
2379  KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
2380  KTR_ATTR_LINKED, sched_tdname(td));
2381  SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL,
2382  flags & SRQ_PREEMPTED);
2383  THREAD_LOCK_ASSERT(td, MA_OWNED);
2384  /*
2385  * Recalculate the priority before we select the target cpu or
2386  * run-queue.
2387  */
2388  if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
2389  sched_priority(td);
2390 #ifdef SMP
2391  /*
2392  * Pick the destination cpu and if it isn't ours transfer to the
2393  * target cpu.
2394  */
2395  cpu = sched_pickcpu(td, flags);
2396  tdq = sched_setcpu(td, cpu, flags);
2397  tdq_add(tdq, td, flags);
2398  if (cpu != PCPU_GET(cpuid)) {
2399  tdq_notify(tdq, td);
2400  return;
2401  }
2402 #else
2403  tdq = TDQ_SELF();
2404  TDQ_LOCK(tdq);
2405  /*
2406  * Now that the thread is moving to the run-queue, set the lock
2407  * to the scheduler's lock.
2408  */
2409  thread_lock_set(td, TDQ_LOCKPTR(tdq));
2410  tdq_add(tdq, td, flags);
2411 #endif
2412  if (!(flags & SRQ_YIELDING))
2413  sched_setpreempt(td);
2414 }
2415 
2416 /*
2417  * Remove a thread from a run-queue without running it. This is used
2418  * when we're stealing a thread from a remote queue. Otherwise all threads
2419  * exit by calling sched_exit_thread() and sched_throw() themselves.
2420  */
2421 void
2422 sched_rem(struct thread *td)
2423 {
2424  struct tdq *tdq;
2425 
2426  KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem",
2427  "prio:%d", td->td_priority);
2428  SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL);
2429  tdq = TDQ_CPU(td->td_sched->ts_cpu);
2430  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2431  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2432  KASSERT(TD_ON_RUNQ(td),
2433  ("sched_rem: thread not on run queue"));
2434  tdq_runq_rem(tdq, td);
2435  tdq_load_rem(tdq, td);
2436  TD_SET_CAN_RUN(td);
2437  if (td->td_priority == tdq->tdq_lowpri)
2438  tdq_setlowpri(tdq, NULL);
2439 }
2440 
2441 /*
2442  * Fetch cpu utilization information. Updates on demand.
2443  */
2444 fixpt_t
2445 sched_pctcpu(struct thread *td)
2446 {
2447  fixpt_t pctcpu;
2448  struct td_sched *ts;
2449 
2450  pctcpu = 0;
2451  ts = td->td_sched;
2452  if (ts == NULL)
2453  return (0);
2454 
2455  THREAD_LOCK_ASSERT(td, MA_OWNED);
2456  sched_pctcpu_update(ts, TD_IS_RUNNING(td));
2457  if (ts->ts_ticks) {
2458  int rtick;
2459 
2460  /* How many rtick per second ? */
2461  rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz);
2462  pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT;
2463  }
2464 
2465  return (pctcpu);
2466 }
2467 
2468 /*
2469  * Enforce affinity settings for a thread. Called after adjustments to
2470  * cpumask.
2471  */
2472 void
2473 sched_affinity(struct thread *td)
2474 {
2475 #ifdef SMP
2476  struct td_sched *ts;
2477 
2478  THREAD_LOCK_ASSERT(td, MA_OWNED);
2479  ts = td->td_sched;
2480  if (THREAD_CAN_SCHED(td, ts->ts_cpu))
2481  return;
2482  if (TD_ON_RUNQ(td)) {
2483  sched_rem(td);
2484  sched_add(td, SRQ_BORING);
2485  return;
2486  }
2487  if (!TD_IS_RUNNING(td))
2488  return;
2489  /*
2490  * Force a switch before returning to userspace. If the
2491  * target thread is not running locally send an ipi to force
2492  * the issue.
2493  */
2494  td->td_flags |= TDF_NEEDRESCHED;
2495  if (td != curthread)
2496  ipi_cpu(ts->ts_cpu, IPI_PREEMPT);
2497 #endif
2498 }
2499 
2500 /*
2501  * Bind a thread to a target cpu.
2502  */
2503 void
2504 sched_bind(struct thread *td, int cpu)
2505 {
2506  struct td_sched *ts;
2507 
2508  THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED);
2509  KASSERT(td == curthread, ("sched_bind: can only bind curthread"));
2510  ts = td->td_sched;
2511  if (ts->ts_flags & TSF_BOUND)
2512  sched_unbind(td);
2513  KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td));
2514  ts->ts_flags |= TSF_BOUND;
2515  sched_pin();
2516  if (PCPU_GET(cpuid) == cpu)
2517  return;
2518  ts->ts_cpu = cpu;
2519  /* When we return from mi_switch we'll be on the correct cpu. */
2520  mi_switch(SW_VOL, NULL);
2521 }
2522 
2523 /*
2524  * Release a bound thread.
2525  */
2526 void
2527 sched_unbind(struct thread *td)
2528 {
2529  struct td_sched *ts;
2530 
2531  THREAD_LOCK_ASSERT(td, MA_OWNED);
2532  KASSERT(td == curthread, ("sched_unbind: can only bind curthread"));
2533  ts = td->td_sched;
2534  if ((ts->ts_flags & TSF_BOUND) == 0)
2535  return;
2536  ts->ts_flags &= ~TSF_BOUND;
2537  sched_unpin();
2538 }
2539 
2540 int
2541 sched_is_bound(struct thread *td)
2542 {
2543  THREAD_LOCK_ASSERT(td, MA_OWNED);
2544  return (td->td_sched->ts_flags & TSF_BOUND);
2545 }
2546 
2547 /*
2548  * Basic yield call.
2549  */
2550 void
2551 sched_relinquish(struct thread *td)
2552 {
2553  thread_lock(td);
2554  mi_switch(SW_VOL | SWT_RELINQUISH, NULL);
2555  thread_unlock(td);
2556 }
2557 
2558 /*
2559  * Return the total system load.
2560  */
2561 int
2563 {
2564 #ifdef SMP
2565  int total;
2566  int i;
2567 
2568  total = 0;
2569  CPU_FOREACH(i)
2570  total += TDQ_CPU(i)->tdq_sysload;
2571  return (total);
2572 #else
2573  return (TDQ_SELF()->tdq_sysload);
2574 #endif
2575 }
2576 
2577 int
2579 {
2580  return (sizeof(struct proc));
2581 }
2582 
2583 int
2585 {
2586  return (sizeof(struct thread) + sizeof(struct td_sched));
2587 }
2588 
2589 #ifdef SMP
2590 #define TDQ_IDLESPIN(tdq) \
2591  ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0)
2592 #else
2593 #define TDQ_IDLESPIN(tdq) 1
2594 #endif
2595 
2596 /*
2597  * The actual idle process.
2598  */
2599 void
2601 {
2602  struct thread *td;
2603  struct tdq *tdq;
2604  int oldswitchcnt, switchcnt;
2605  int i;
2606 
2607  mtx_assert(&Giant, MA_NOTOWNED);
2608  td = curthread;
2609  tdq = TDQ_SELF();
2610  THREAD_NO_SLEEPING();
2611  oldswitchcnt = -1;
2612  for (;;) {
2613  if (tdq->tdq_load) {
2614  thread_lock(td);
2615  mi_switch(SW_VOL | SWT_IDLE, NULL);
2616  thread_unlock(td);
2617  }
2618  switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2619 #ifdef SMP
2620  if (switchcnt != oldswitchcnt) {
2621  oldswitchcnt = switchcnt;
2622  if (tdq_idled(tdq) == 0)
2623  continue;
2624  }
2625  switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2626 #else
2627  oldswitchcnt = switchcnt;
2628 #endif
2629  /*
2630  * If we're switching very frequently, spin while checking
2631  * for load rather than entering a low power state that
2632  * may require an IPI. However, don't do any busy
2633  * loops while on SMT machines as this simply steals
2634  * cycles from cores doing useful work.
2635  */
2636  if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) {
2637  for (i = 0; i < sched_idlespins; i++) {
2638  if (tdq->tdq_load)
2639  break;
2640  cpu_spinwait();
2641  }
2642  }
2643 
2644  /* If there was context switch during spin, restart it. */
2645  switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2646  if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt)
2647  continue;
2648 
2649  /* Run main MD idle handler. */
2650  tdq->tdq_cpu_idle = 1;
2651  /*
2652  * Make sure that tdq_cpu_idle update is globally visible
2653  * before cpu_idle() read tdq_load. The order is important
2654  * to avoid race with tdq_notify.
2655  */
2656  mb();
2657  cpu_idle(switchcnt * 4 > sched_idlespinthresh);
2658  tdq->tdq_cpu_idle = 0;
2659 
2660  /*
2661  * Account thread-less hardware interrupts and
2662  * other wakeup reasons equal to context switches.
2663  */
2664  switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2665  if (switchcnt != oldswitchcnt)
2666  continue;
2667  tdq->tdq_switchcnt++;
2668  oldswitchcnt++;
2669  }
2670 }
2671 
2672 /*
2673  * A CPU is entering for the first time or a thread is exiting.
2674  */
2675 void
2676 sched_throw(struct thread *td)
2677 {
2678  struct thread *newtd;
2679  struct tdq *tdq;
2680 
2681  tdq = TDQ_SELF();
2682  if (td == NULL) {
2683  /* Correct spinlock nesting and acquire the correct lock. */
2684  TDQ_LOCK(tdq);
2685  spinlock_exit();
2686  PCPU_SET(switchtime, cpu_ticks());
2687  PCPU_SET(switchticks, ticks);
2688  } else {
2689  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2690  tdq_load_rem(tdq, td);
2691  lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object);
2692  }
2693  KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count"));
2694  newtd = choosethread();
2695  TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd;
2696  cpu_throw(td, newtd); /* doesn't return */
2697 }
2698 
2699 /*
2700  * This is called from fork_exit(). Just acquire the correct locks and
2701  * let fork do the rest of the work.
2702  */
2703 void
2704 sched_fork_exit(struct thread *td)
2705 {
2706  struct tdq *tdq;
2707  int cpuid;
2708 
2709  /*
2710  * Finish setting up thread glue so that it begins execution in a
2711  * non-nested critical section with the scheduler lock held.
2712  */
2713  cpuid = PCPU_GET(cpuid);
2714  tdq = TDQ_CPU(cpuid);
2715  if (TD_IS_IDLETHREAD(td))
2716  td->td_lock = TDQ_LOCKPTR(tdq);
2717  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2718  td->td_oncpu = cpuid;
2719  TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED);
2720  lock_profile_obtain_lock_success(
2721  &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__);
2722 }
2723 
2724 /*
2725  * Create on first use to catch odd startup conditons.
2726  */
2727 char *
2728 sched_tdname(struct thread *td)
2729 {
2730 #ifdef KTR
2731  struct td_sched *ts;
2732 
2733  ts = td->td_sched;
2734  if (ts->ts_name[0] == '\0')
2735  snprintf(ts->ts_name, sizeof(ts->ts_name),
2736  "%s tid %d", td->td_name, td->td_tid);
2737  return (ts->ts_name);
2738 #else
2739  return (td->td_name);
2740 #endif
2741 }
2742 
2743 #ifdef KTR
2744 void
2745 sched_clear_tdname(struct thread *td)
2746 {
2747  struct td_sched *ts;
2748 
2749  ts = td->td_sched;
2750  ts->ts_name[0] = '\0';
2751 }
2752 #endif
2753 
2754 #ifdef SMP
2755 
2756 /*
2757  * Build the CPU topology dump string. Is recursively called to collect
2758  * the topology tree.
2759  */
2760 static int
2761 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg,
2762  int indent)
2763 {
2764  char cpusetbuf[CPUSETBUFSIZ];
2765  int i, first;
2766 
2767  sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent,
2768  "", 1 + indent / 2, cg->cg_level);
2769  sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "",
2770  cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask));
2771  first = TRUE;
2772  for (i = 0; i < MAXCPU; i++) {
2773  if (CPU_ISSET(i, &cg->cg_mask)) {
2774  if (!first)
2775  sbuf_printf(sb, ", ");
2776  else
2777  first = FALSE;
2778  sbuf_printf(sb, "%d", i);
2779  }
2780  }
2781  sbuf_printf(sb, "</cpu>\n");
2782 
2783  if (cg->cg_flags != 0) {
2784  sbuf_printf(sb, "%*s <flags>", indent, "");
2785  if ((cg->cg_flags & CG_FLAG_HTT) != 0)
2786  sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>");
2787  if ((cg->cg_flags & CG_FLAG_THREAD) != 0)
2788  sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>");
2789  if ((cg->cg_flags & CG_FLAG_SMT) != 0)
2790  sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>");
2791  sbuf_printf(sb, "</flags>\n");
2792  }
2793 
2794  if (cg->cg_children > 0) {
2795  sbuf_printf(sb, "%*s <children>\n", indent, "");
2796  for (i = 0; i < cg->cg_children; i++)
2797  sysctl_kern_sched_topology_spec_internal(sb,
2798  &cg->cg_child[i], indent+2);
2799  sbuf_printf(sb, "%*s </children>\n", indent, "");
2800  }
2801  sbuf_printf(sb, "%*s</group>\n", indent, "");
2802  return (0);
2803 }
2804 
2805 /*
2806  * Sysctl handler for retrieving topology dump. It's a wrapper for
2807  * the recursive sysctl_kern_smp_topology_spec_internal().
2808  */
2809 static int
2810 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS)
2811 {
2812  struct sbuf *topo;
2813  int err;
2814 
2815  KASSERT(cpu_top != NULL, ("cpu_top isn't initialized"));
2816 
2817  topo = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND);
2818  if (topo == NULL)
2819  return (ENOMEM);
2820 
2821  sbuf_printf(topo, "<groups>\n");
2822  err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1);
2823  sbuf_printf(topo, "</groups>\n");
2824 
2825  if (err == 0) {
2826  sbuf_finish(topo);
2827  err = SYSCTL_OUT(req, sbuf_data(topo), sbuf_len(topo));
2828  }
2829  sbuf_delete(topo);
2830  return (err);
2831 }
2832 
2833 #endif
2834 
2835 static int
2836 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
2837 {
2838  int error, new_val, period;
2839 
2840  period = 1000000 / realstathz;
2841  new_val = period * sched_slice;
2842  error = sysctl_handle_int(oidp, &new_val, 0, req);
2843  if (error != 0 || req->newptr == NULL)
2844  return (error);
2845  if (new_val <= 0)
2846  return (EINVAL);
2847  sched_slice = imax(1, (new_val + period / 2) / period);
2848  sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR;
2849  hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
2850  realstathz);
2851  return (0);
2852 }
2853 
2854 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler");
2855 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0,
2856  "Scheduler name");
2857 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW,
2858  NULL, 0, sysctl_kern_quantum, "I",
2859  "Quantum for timeshare threads in microseconds");
2860 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
2861  "Quantum for timeshare threads in stathz ticks");
2862 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0,
2863  "Interactivity score threshold");
2864 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW,
2865  &preempt_thresh, 0,
2866  "Maximal (lowest) priority for preemption");
2867 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0,
2868  "Assign static kernel priorities to sleeping threads");
2869 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0,
2870  "Number of times idle thread will spin waiting for new work");
2871 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW,
2873  "Threshold before we will permit idle thread spinning");
2874 #ifdef SMP
2875 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0,
2876  "Number of hz ticks to keep thread affinity for");
2877 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0,
2878  "Enables the long-term load balancer");
2879 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW,
2880  &balance_interval, 0,
2881  "Average period in stathz ticks to run the long-term balancer");
2882 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0,
2883  "Attempts to steal work from other cores before idling");
2884 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0,
2885  "Minimum load on remote CPU before we'll steal");
2886 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING |
2887  CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A",
2888  "XML dump of detected CPU topology");
2889 #endif
2890 
2891 /* ps compat. All cpu percentages from ULE are weighted. */
2892 static int ccpu = 0;
2893 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");