FreeBSD/Linux Kernel Cross Reference
sys/kern/sched_4bsd.c
1 /*-
2 * Copyright (c) 1982, 1986, 1990, 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 * (c) UNIX System Laboratories, Inc.
5 * All or some portions of this file are derived from material licensed
6 * to the University of California by American Telephone and Telegraph
7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8 * the permission of UNIX System Laboratories, Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 4. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD: releng/11.0/sys/kern/sched_4bsd.c 303884 2016-08-09 18:56:29Z jhb $");
37
38 #include "opt_hwpmc_hooks.h"
39 #include "opt_sched.h"
40
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/cpuset.h>
44 #include <sys/kernel.h>
45 #include <sys/ktr.h>
46 #include <sys/lock.h>
47 #include <sys/kthread.h>
48 #include <sys/mutex.h>
49 #include <sys/proc.h>
50 #include <sys/resourcevar.h>
51 #include <sys/sched.h>
52 #include <sys/sdt.h>
53 #include <sys/smp.h>
54 #include <sys/sysctl.h>
55 #include <sys/sx.h>
56 #include <sys/turnstile.h>
57 #include <sys/umtx.h>
58 #include <machine/pcb.h>
59 #include <machine/smp.h>
60
61 #ifdef HWPMC_HOOKS
62 #include <sys/pmckern.h>
63 #endif
64
65 #ifdef KDTRACE_HOOKS
66 #include <sys/dtrace_bsd.h>
67 int dtrace_vtime_active;
68 dtrace_vtime_switch_func_t dtrace_vtime_switch_func;
69 #endif
70
71 /*
72 * INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in
73 * the range 100-256 Hz (approximately).
74 */
75 #define ESTCPULIM(e) \
76 min((e), INVERSE_ESTCPU_WEIGHT * (NICE_WEIGHT * (PRIO_MAX - PRIO_MIN) - \
77 RQ_PPQ) + INVERSE_ESTCPU_WEIGHT - 1)
78 #ifdef SMP
79 #define INVERSE_ESTCPU_WEIGHT (8 * smp_cpus)
80 #else
81 #define INVERSE_ESTCPU_WEIGHT 8 /* 1 / (priorities per estcpu level). */
82 #endif
83 #define NICE_WEIGHT 1 /* Priorities per nice level. */
84
85 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX)))
86
87 /*
88 * The schedulable entity that runs a context.
89 * This is an extension to the thread structure and is tailored to
90 * the requirements of this scheduler.
91 * All fields are protected by the scheduler lock.
92 */
93 struct td_sched {
94 fixpt_t ts_pctcpu; /* %cpu during p_swtime. */
95 u_int ts_estcpu; /* Estimated cpu utilization. */
96 int ts_cpticks; /* Ticks of cpu time. */
97 int ts_slptime; /* Seconds !RUNNING. */
98 int ts_slice; /* Remaining part of time slice. */
99 int ts_flags;
100 struct runq *ts_runq; /* runq the thread is currently on */
101 #ifdef KTR
102 char ts_name[TS_NAME_LEN];
103 #endif
104 };
105
106 /* flags kept in td_flags */
107 #define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */
108 #define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */
109 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */
110
111 /* flags kept in ts_flags */
112 #define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */
113
114 #define SKE_RUNQ_PCPU(ts) \
115 ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq)
116
117 #define THREAD_CAN_SCHED(td, cpu) \
118 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask)
119
120 _Static_assert(sizeof(struct thread) + sizeof(struct td_sched) <=
121 sizeof(struct thread0_storage),
122 "increase struct thread0_storage.t0st_sched size");
123
124 static struct mtx sched_lock;
125
126 static int realstathz = 127; /* stathz is sometimes 0 and run off of hz. */
127 static int sched_tdcnt; /* Total runnable threads in the system. */
128 static int sched_slice = 12; /* Thread run time before rescheduling. */
129
130 static void setup_runqs(void);
131 static void schedcpu(void);
132 static void schedcpu_thread(void);
133 static void sched_priority(struct thread *td, u_char prio);
134 static void sched_setup(void *dummy);
135 static void maybe_resched(struct thread *td);
136 static void updatepri(struct thread *td);
137 static void resetpriority(struct thread *td);
138 static void resetpriority_thread(struct thread *td);
139 #ifdef SMP
140 static int sched_pickcpu(struct thread *td);
141 static int forward_wakeup(int cpunum);
142 static void kick_other_cpu(int pri, int cpuid);
143 #endif
144
145 static struct kproc_desc sched_kp = {
146 "schedcpu",
147 schedcpu_thread,
148 NULL
149 };
150 SYSINIT(schedcpu, SI_SUB_LAST, SI_ORDER_FIRST, kproc_start,
151 &sched_kp);
152 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL);
153
154 static void sched_initticks(void *dummy);
155 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks,
156 NULL);
157
158 /*
159 * Global run queue.
160 */
161 static struct runq runq;
162
163 #ifdef SMP
164 /*
165 * Per-CPU run queues
166 */
167 static struct runq runq_pcpu[MAXCPU];
168 long runq_length[MAXCPU];
169
170 static cpuset_t idle_cpus_mask;
171 #endif
172
173 struct pcpuidlestat {
174 u_int idlecalls;
175 u_int oldidlecalls;
176 };
177 static DPCPU_DEFINE(struct pcpuidlestat, idlestat);
178
179 static void
180 setup_runqs(void)
181 {
182 #ifdef SMP
183 int i;
184
185 for (i = 0; i < MAXCPU; ++i)
186 runq_init(&runq_pcpu[i]);
187 #endif
188
189 runq_init(&runq);
190 }
191
192 static int
193 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
194 {
195 int error, new_val, period;
196
197 period = 1000000 / realstathz;
198 new_val = period * sched_slice;
199 error = sysctl_handle_int(oidp, &new_val, 0, req);
200 if (error != 0 || req->newptr == NULL)
201 return (error);
202 if (new_val <= 0)
203 return (EINVAL);
204 sched_slice = imax(1, (new_val + period / 2) / period);
205 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
206 realstathz);
207 return (0);
208 }
209
210 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler");
211
212 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0,
213 "Scheduler name");
214 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW,
215 NULL, 0, sysctl_kern_quantum, "I",
216 "Quantum for timeshare threads in microseconds");
217 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
218 "Quantum for timeshare threads in stathz ticks");
219 #ifdef SMP
220 /* Enable forwarding of wakeups to all other cpus */
221 static SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL,
222 "Kernel SMP");
223
224 static int runq_fuzz = 1;
225 SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, "");
226
227 static int forward_wakeup_enabled = 1;
228 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW,
229 &forward_wakeup_enabled, 0,
230 "Forwarding of wakeup to idle CPUs");
231
232 static int forward_wakeups_requested = 0;
233 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD,
234 &forward_wakeups_requested, 0,
235 "Requests for Forwarding of wakeup to idle CPUs");
236
237 static int forward_wakeups_delivered = 0;
238 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD,
239 &forward_wakeups_delivered, 0,
240 "Completed Forwarding of wakeup to idle CPUs");
241
242 static int forward_wakeup_use_mask = 1;
243 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW,
244 &forward_wakeup_use_mask, 0,
245 "Use the mask of idle cpus");
246
247 static int forward_wakeup_use_loop = 0;
248 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW,
249 &forward_wakeup_use_loop, 0,
250 "Use a loop to find idle cpus");
251
252 #endif
253 #if 0
254 static int sched_followon = 0;
255 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW,
256 &sched_followon, 0,
257 "allow threads to share a quantum");
258 #endif
259
260 SDT_PROVIDER_DEFINE(sched);
261
262 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *",
263 "struct proc *", "uint8_t");
264 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *",
265 "struct proc *", "void *");
266 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *",
267 "struct proc *", "void *", "int");
268 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *",
269 "struct proc *", "uint8_t", "struct thread *");
270 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int");
271 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *",
272 "struct proc *");
273 SDT_PROBE_DEFINE(sched, , , on__cpu);
274 SDT_PROBE_DEFINE(sched, , , remain__cpu);
275 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *",
276 "struct proc *");
277
278 static __inline void
279 sched_load_add(void)
280 {
281
282 sched_tdcnt++;
283 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt);
284 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt);
285 }
286
287 static __inline void
288 sched_load_rem(void)
289 {
290
291 sched_tdcnt--;
292 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt);
293 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt);
294 }
295 /*
296 * Arrange to reschedule if necessary, taking the priorities and
297 * schedulers into account.
298 */
299 static void
300 maybe_resched(struct thread *td)
301 {
302
303 THREAD_LOCK_ASSERT(td, MA_OWNED);
304 if (td->td_priority < curthread->td_priority)
305 curthread->td_flags |= TDF_NEEDRESCHED;
306 }
307
308 /*
309 * This function is called when a thread is about to be put on run queue
310 * because it has been made runnable or its priority has been adjusted. It
311 * determines if the new thread should be immediately preempted to. If so,
312 * it switches to it and eventually returns true. If not, it returns false
313 * so that the caller may place the thread on an appropriate run queue.
314 */
315 int
316 maybe_preempt(struct thread *td)
317 {
318 #ifdef PREEMPTION
319 struct thread *ctd;
320 int cpri, pri;
321
322 /*
323 * The new thread should not preempt the current thread if any of the
324 * following conditions are true:
325 *
326 * - The kernel is in the throes of crashing (panicstr).
327 * - The current thread has a higher (numerically lower) or
328 * equivalent priority. Note that this prevents curthread from
329 * trying to preempt to itself.
330 * - It is too early in the boot for context switches (cold is set).
331 * - The current thread has an inhibitor set or is in the process of
332 * exiting. In this case, the current thread is about to switch
333 * out anyways, so there's no point in preempting. If we did,
334 * the current thread would not be properly resumed as well, so
335 * just avoid that whole landmine.
336 * - If the new thread's priority is not a realtime priority and
337 * the current thread's priority is not an idle priority and
338 * FULL_PREEMPTION is disabled.
339 *
340 * If all of these conditions are false, but the current thread is in
341 * a nested critical section, then we have to defer the preemption
342 * until we exit the critical section. Otherwise, switch immediately
343 * to the new thread.
344 */
345 ctd = curthread;
346 THREAD_LOCK_ASSERT(td, MA_OWNED);
347 KASSERT((td->td_inhibitors == 0),
348 ("maybe_preempt: trying to run inhibited thread"));
349 pri = td->td_priority;
350 cpri = ctd->td_priority;
351 if (panicstr != NULL || pri >= cpri || cold /* || dumping */ ||
352 TD_IS_INHIBITED(ctd))
353 return (0);
354 #ifndef FULL_PREEMPTION
355 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE)
356 return (0);
357 #endif
358
359 if (ctd->td_critnest > 1) {
360 CTR1(KTR_PROC, "maybe_preempt: in critical section %d",
361 ctd->td_critnest);
362 ctd->td_owepreempt = 1;
363 return (0);
364 }
365 /*
366 * Thread is runnable but not yet put on system run queue.
367 */
368 MPASS(ctd->td_lock == td->td_lock);
369 MPASS(TD_ON_RUNQ(td));
370 TD_SET_RUNNING(td);
371 CTR3(KTR_PROC, "preempting to thread %p (pid %d, %s)\n", td,
372 td->td_proc->p_pid, td->td_name);
373 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, td);
374 /*
375 * td's lock pointer may have changed. We have to return with it
376 * locked.
377 */
378 spinlock_enter();
379 thread_unlock(ctd);
380 thread_lock(td);
381 spinlock_exit();
382 return (1);
383 #else
384 return (0);
385 #endif
386 }
387
388 /*
389 * Constants for digital decay and forget:
390 * 90% of (ts_estcpu) usage in 5 * loadav time
391 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive)
392 * Note that, as ps(1) mentions, this can let percentages
393 * total over 100% (I've seen 137.9% for 3 processes).
394 *
395 * Note that schedclock() updates ts_estcpu and p_cpticks asynchronously.
396 *
397 * We wish to decay away 90% of ts_estcpu in (5 * loadavg) seconds.
398 * That is, the system wants to compute a value of decay such
399 * that the following for loop:
400 * for (i = 0; i < (5 * loadavg); i++)
401 * ts_estcpu *= decay;
402 * will compute
403 * ts_estcpu *= 0.1;
404 * for all values of loadavg:
405 *
406 * Mathematically this loop can be expressed by saying:
407 * decay ** (5 * loadavg) ~= .1
408 *
409 * The system computes decay as:
410 * decay = (2 * loadavg) / (2 * loadavg + 1)
411 *
412 * We wish to prove that the system's computation of decay
413 * will always fulfill the equation:
414 * decay ** (5 * loadavg) ~= .1
415 *
416 * If we compute b as:
417 * b = 2 * loadavg
418 * then
419 * decay = b / (b + 1)
420 *
421 * We now need to prove two things:
422 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1)
423 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg)
424 *
425 * Facts:
426 * For x close to zero, exp(x) =~ 1 + x, since
427 * exp(x) = 0! + x**1/1! + x**2/2! + ... .
428 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b.
429 * For x close to zero, ln(1+x) =~ x, since
430 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1
431 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1).
432 * ln(.1) =~ -2.30
433 *
434 * Proof of (1):
435 * Solve (factor)**(power) =~ .1 given power (5*loadav):
436 * solving for factor,
437 * ln(factor) =~ (-2.30/5*loadav), or
438 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) =
439 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED
440 *
441 * Proof of (2):
442 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)):
443 * solving for power,
444 * power*ln(b/(b+1)) =~ -2.30, or
445 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED
446 *
447 * Actual power values for the implemented algorithm are as follows:
448 * loadav: 1 2 3 4
449 * power: 5.68 10.32 14.94 19.55
450 */
451
452 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */
453 #define loadfactor(loadav) (2 * (loadav))
454 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE))
455
456 /* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */
457 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
458 SYSCTL_UINT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");
459
460 /*
461 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the
462 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below
463 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT).
464 *
465 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used:
466 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits).
467 *
468 * If you don't want to bother with the faster/more-accurate formula, you
469 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate
470 * (more general) method of calculating the %age of CPU used by a process.
471 */
472 #define CCPU_SHIFT 11
473
474 /*
475 * Recompute process priorities, every hz ticks.
476 * MP-safe, called without the Giant mutex.
477 */
478 /* ARGSUSED */
479 static void
480 schedcpu(void)
481 {
482 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
483 struct thread *td;
484 struct proc *p;
485 struct td_sched *ts;
486 int awake;
487
488 sx_slock(&allproc_lock);
489 FOREACH_PROC_IN_SYSTEM(p) {
490 PROC_LOCK(p);
491 if (p->p_state == PRS_NEW) {
492 PROC_UNLOCK(p);
493 continue;
494 }
495 FOREACH_THREAD_IN_PROC(p, td) {
496 awake = 0;
497 ts = td_get_sched(td);
498 thread_lock(td);
499 /*
500 * Increment sleep time (if sleeping). We
501 * ignore overflow, as above.
502 */
503 /*
504 * The td_sched slptimes are not touched in wakeup
505 * because the thread may not HAVE everything in
506 * memory? XXX I think this is out of date.
507 */
508 if (TD_ON_RUNQ(td)) {
509 awake = 1;
510 td->td_flags &= ~TDF_DIDRUN;
511 } else if (TD_IS_RUNNING(td)) {
512 awake = 1;
513 /* Do not clear TDF_DIDRUN */
514 } else if (td->td_flags & TDF_DIDRUN) {
515 awake = 1;
516 td->td_flags &= ~TDF_DIDRUN;
517 }
518
519 /*
520 * ts_pctcpu is only for ps and ttyinfo().
521 */
522 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT;
523 /*
524 * If the td_sched has been idle the entire second,
525 * stop recalculating its priority until
526 * it wakes up.
527 */
528 if (ts->ts_cpticks != 0) {
529 #if (FSHIFT >= CCPU_SHIFT)
530 ts->ts_pctcpu += (realstathz == 100)
531 ? ((fixpt_t) ts->ts_cpticks) <<
532 (FSHIFT - CCPU_SHIFT) :
533 100 * (((fixpt_t) ts->ts_cpticks)
534 << (FSHIFT - CCPU_SHIFT)) / realstathz;
535 #else
536 ts->ts_pctcpu += ((FSCALE - ccpu) *
537 (ts->ts_cpticks *
538 FSCALE / realstathz)) >> FSHIFT;
539 #endif
540 ts->ts_cpticks = 0;
541 }
542 /*
543 * If there are ANY running threads in this process,
544 * then don't count it as sleeping.
545 * XXX: this is broken.
546 */
547 if (awake) {
548 if (ts->ts_slptime > 1) {
549 /*
550 * In an ideal world, this should not
551 * happen, because whoever woke us
552 * up from the long sleep should have
553 * unwound the slptime and reset our
554 * priority before we run at the stale
555 * priority. Should KASSERT at some
556 * point when all the cases are fixed.
557 */
558 updatepri(td);
559 }
560 ts->ts_slptime = 0;
561 } else
562 ts->ts_slptime++;
563 if (ts->ts_slptime > 1) {
564 thread_unlock(td);
565 continue;
566 }
567 ts->ts_estcpu = decay_cpu(loadfac, ts->ts_estcpu);
568 resetpriority(td);
569 resetpriority_thread(td);
570 thread_unlock(td);
571 }
572 PROC_UNLOCK(p);
573 }
574 sx_sunlock(&allproc_lock);
575 }
576
577 /*
578 * Main loop for a kthread that executes schedcpu once a second.
579 */
580 static void
581 schedcpu_thread(void)
582 {
583
584 for (;;) {
585 schedcpu();
586 pause("-", hz);
587 }
588 }
589
590 /*
591 * Recalculate the priority of a process after it has slept for a while.
592 * For all load averages >= 1 and max ts_estcpu of 255, sleeping for at
593 * least six times the loadfactor will decay ts_estcpu to zero.
594 */
595 static void
596 updatepri(struct thread *td)
597 {
598 struct td_sched *ts;
599 fixpt_t loadfac;
600 unsigned int newcpu;
601
602 ts = td_get_sched(td);
603 loadfac = loadfactor(averunnable.ldavg[0]);
604 if (ts->ts_slptime > 5 * loadfac)
605 ts->ts_estcpu = 0;
606 else {
607 newcpu = ts->ts_estcpu;
608 ts->ts_slptime--; /* was incremented in schedcpu() */
609 while (newcpu && --ts->ts_slptime)
610 newcpu = decay_cpu(loadfac, newcpu);
611 ts->ts_estcpu = newcpu;
612 }
613 }
614
615 /*
616 * Compute the priority of a process when running in user mode.
617 * Arrange to reschedule if the resulting priority is better
618 * than that of the current process.
619 */
620 static void
621 resetpriority(struct thread *td)
622 {
623 u_int newpriority;
624
625 if (td->td_pri_class != PRI_TIMESHARE)
626 return;
627 newpriority = PUSER +
628 td_get_sched(td)->ts_estcpu / INVERSE_ESTCPU_WEIGHT +
629 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN);
630 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE),
631 PRI_MAX_TIMESHARE);
632 sched_user_prio(td, newpriority);
633 }
634
635 /*
636 * Update the thread's priority when the associated process's user
637 * priority changes.
638 */
639 static void
640 resetpriority_thread(struct thread *td)
641 {
642
643 /* Only change threads with a time sharing user priority. */
644 if (td->td_priority < PRI_MIN_TIMESHARE ||
645 td->td_priority > PRI_MAX_TIMESHARE)
646 return;
647
648 /* XXX the whole needresched thing is broken, but not silly. */
649 maybe_resched(td);
650
651 sched_prio(td, td->td_user_pri);
652 }
653
654 /* ARGSUSED */
655 static void
656 sched_setup(void *dummy)
657 {
658
659 setup_runqs();
660
661 /* Account for thread0. */
662 sched_load_add();
663 }
664
665 /*
666 * This routine determines time constants after stathz and hz are setup.
667 */
668 static void
669 sched_initticks(void *dummy)
670 {
671
672 realstathz = stathz ? stathz : hz;
673 sched_slice = realstathz / 10; /* ~100ms */
674 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
675 realstathz);
676 }
677
678 /* External interfaces start here */
679
680 /*
681 * Very early in the boot some setup of scheduler-specific
682 * parts of proc0 and of some scheduler resources needs to be done.
683 * Called from:
684 * proc0_init()
685 */
686 void
687 schedinit(void)
688 {
689
690 /*
691 * Set up the scheduler specific parts of thread0.
692 */
693 thread0.td_lock = &sched_lock;
694 td_get_sched(&thread0)->ts_slice = sched_slice;
695 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE);
696 }
697
698 int
699 sched_runnable(void)
700 {
701 #ifdef SMP
702 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]);
703 #else
704 return runq_check(&runq);
705 #endif
706 }
707
708 int
709 sched_rr_interval(void)
710 {
711
712 /* Convert sched_slice from stathz to hz. */
713 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz));
714 }
715
716 /*
717 * We adjust the priority of the current process. The priority of a
718 * process gets worse as it accumulates CPU time. The cpu usage
719 * estimator (ts_estcpu) is increased here. resetpriority() will
720 * compute a different priority each time ts_estcpu increases by
721 * INVERSE_ESTCPU_WEIGHT (until PRI_MAX_TIMESHARE is reached). The
722 * cpu usage estimator ramps up quite quickly when the process is
723 * running (linearly), and decays away exponentially, at a rate which
724 * is proportionally slower when the system is busy. The basic
725 * principle is that the system will 90% forget that the process used
726 * a lot of CPU time in 5 * loadav seconds. This causes the system to
727 * favor processes which haven't run much recently, and to round-robin
728 * among other processes.
729 */
730 void
731 sched_clock(struct thread *td)
732 {
733 struct pcpuidlestat *stat;
734 struct td_sched *ts;
735
736 THREAD_LOCK_ASSERT(td, MA_OWNED);
737 ts = td_get_sched(td);
738
739 ts->ts_cpticks++;
740 ts->ts_estcpu = ESTCPULIM(ts->ts_estcpu + 1);
741 if ((ts->ts_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) {
742 resetpriority(td);
743 resetpriority_thread(td);
744 }
745
746 /*
747 * Force a context switch if the current thread has used up a full
748 * time slice (default is 100ms).
749 */
750 if (!TD_IS_IDLETHREAD(td) && --ts->ts_slice <= 0) {
751 ts->ts_slice = sched_slice;
752 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND;
753 }
754
755 stat = DPCPU_PTR(idlestat);
756 stat->oldidlecalls = stat->idlecalls;
757 stat->idlecalls = 0;
758 }
759
760 /*
761 * Charge child's scheduling CPU usage to parent.
762 */
763 void
764 sched_exit(struct proc *p, struct thread *td)
765 {
766
767 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit",
768 "prio:%d", td->td_priority);
769
770 PROC_LOCK_ASSERT(p, MA_OWNED);
771 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td);
772 }
773
774 void
775 sched_exit_thread(struct thread *td, struct thread *child)
776 {
777
778 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit",
779 "prio:%d", child->td_priority);
780 thread_lock(td);
781 td_get_sched(td)->ts_estcpu = ESTCPULIM(td_get_sched(td)->ts_estcpu +
782 td_get_sched(child)->ts_estcpu);
783 thread_unlock(td);
784 thread_lock(child);
785 if ((child->td_flags & TDF_NOLOAD) == 0)
786 sched_load_rem();
787 thread_unlock(child);
788 }
789
790 void
791 sched_fork(struct thread *td, struct thread *childtd)
792 {
793 sched_fork_thread(td, childtd);
794 }
795
796 void
797 sched_fork_thread(struct thread *td, struct thread *childtd)
798 {
799 struct td_sched *ts, *tsc;
800
801 childtd->td_oncpu = NOCPU;
802 childtd->td_lastcpu = NOCPU;
803 childtd->td_lock = &sched_lock;
804 childtd->td_cpuset = cpuset_ref(td->td_cpuset);
805 childtd->td_priority = childtd->td_base_pri;
806 ts = td_get_sched(childtd);
807 bzero(ts, sizeof(*ts));
808 tsc = td_get_sched(td);
809 ts->ts_estcpu = tsc->ts_estcpu;
810 ts->ts_flags |= (tsc->ts_flags & TSF_AFFINITY);
811 ts->ts_slice = 1;
812 }
813
814 void
815 sched_nice(struct proc *p, int nice)
816 {
817 struct thread *td;
818
819 PROC_LOCK_ASSERT(p, MA_OWNED);
820 p->p_nice = nice;
821 FOREACH_THREAD_IN_PROC(p, td) {
822 thread_lock(td);
823 resetpriority(td);
824 resetpriority_thread(td);
825 thread_unlock(td);
826 }
827 }
828
829 void
830 sched_class(struct thread *td, int class)
831 {
832 THREAD_LOCK_ASSERT(td, MA_OWNED);
833 td->td_pri_class = class;
834 }
835
836 /*
837 * Adjust the priority of a thread.
838 */
839 static void
840 sched_priority(struct thread *td, u_char prio)
841 {
842
843
844 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change",
845 "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED,
846 sched_tdname(curthread));
847 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio);
848 if (td != curthread && prio > td->td_priority) {
849 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread),
850 "lend prio", "prio:%d", td->td_priority, "new prio:%d",
851 prio, KTR_ATTR_LINKED, sched_tdname(td));
852 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio,
853 curthread);
854 }
855 THREAD_LOCK_ASSERT(td, MA_OWNED);
856 if (td->td_priority == prio)
857 return;
858 td->td_priority = prio;
859 if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) {
860 sched_rem(td);
861 sched_add(td, SRQ_BORING);
862 }
863 }
864
865 /*
866 * Update a thread's priority when it is lent another thread's
867 * priority.
868 */
869 void
870 sched_lend_prio(struct thread *td, u_char prio)
871 {
872
873 td->td_flags |= TDF_BORROWING;
874 sched_priority(td, prio);
875 }
876
877 /*
878 * Restore a thread's priority when priority propagation is
879 * over. The prio argument is the minimum priority the thread
880 * needs to have to satisfy other possible priority lending
881 * requests. If the thread's regulary priority is less
882 * important than prio the thread will keep a priority boost
883 * of prio.
884 */
885 void
886 sched_unlend_prio(struct thread *td, u_char prio)
887 {
888 u_char base_pri;
889
890 if (td->td_base_pri >= PRI_MIN_TIMESHARE &&
891 td->td_base_pri <= PRI_MAX_TIMESHARE)
892 base_pri = td->td_user_pri;
893 else
894 base_pri = td->td_base_pri;
895 if (prio >= base_pri) {
896 td->td_flags &= ~TDF_BORROWING;
897 sched_prio(td, base_pri);
898 } else
899 sched_lend_prio(td, prio);
900 }
901
902 void
903 sched_prio(struct thread *td, u_char prio)
904 {
905 u_char oldprio;
906
907 /* First, update the base priority. */
908 td->td_base_pri = prio;
909
910 /*
911 * If the thread is borrowing another thread's priority, don't ever
912 * lower the priority.
913 */
914 if (td->td_flags & TDF_BORROWING && td->td_priority < prio)
915 return;
916
917 /* Change the real priority. */
918 oldprio = td->td_priority;
919 sched_priority(td, prio);
920
921 /*
922 * If the thread is on a turnstile, then let the turnstile update
923 * its state.
924 */
925 if (TD_ON_LOCK(td) && oldprio != prio)
926 turnstile_adjust(td, oldprio);
927 }
928
929 void
930 sched_user_prio(struct thread *td, u_char prio)
931 {
932
933 THREAD_LOCK_ASSERT(td, MA_OWNED);
934 td->td_base_user_pri = prio;
935 if (td->td_lend_user_pri <= prio)
936 return;
937 td->td_user_pri = prio;
938 }
939
940 void
941 sched_lend_user_prio(struct thread *td, u_char prio)
942 {
943
944 THREAD_LOCK_ASSERT(td, MA_OWNED);
945 td->td_lend_user_pri = prio;
946 td->td_user_pri = min(prio, td->td_base_user_pri);
947 if (td->td_priority > td->td_user_pri)
948 sched_prio(td, td->td_user_pri);
949 else if (td->td_priority != td->td_user_pri)
950 td->td_flags |= TDF_NEEDRESCHED;
951 }
952
953 void
954 sched_sleep(struct thread *td, int pri)
955 {
956
957 THREAD_LOCK_ASSERT(td, MA_OWNED);
958 td->td_slptick = ticks;
959 td_get_sched(td)->ts_slptime = 0;
960 if (pri != 0 && PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
961 sched_prio(td, pri);
962 if (TD_IS_SUSPENDED(td) || pri >= PSOCK)
963 td->td_flags |= TDF_CANSWAP;
964 }
965
966 void
967 sched_switch(struct thread *td, struct thread *newtd, int flags)
968 {
969 struct mtx *tmtx;
970 struct td_sched *ts;
971 struct proc *p;
972 int preempted;
973
974 tmtx = NULL;
975 ts = td_get_sched(td);
976 p = td->td_proc;
977
978 THREAD_LOCK_ASSERT(td, MA_OWNED);
979
980 /*
981 * Switch to the sched lock to fix things up and pick
982 * a new thread.
983 * Block the td_lock in order to avoid breaking the critical path.
984 */
985 if (td->td_lock != &sched_lock) {
986 mtx_lock_spin(&sched_lock);
987 tmtx = thread_lock_block(td);
988 }
989
990 if ((td->td_flags & TDF_NOLOAD) == 0)
991 sched_load_rem();
992
993 td->td_lastcpu = td->td_oncpu;
994 preempted = !((td->td_flags & TDF_SLICEEND) ||
995 (flags & SWT_RELINQUISH));
996 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND);
997 td->td_owepreempt = 0;
998 td->td_oncpu = NOCPU;
999
1000 /*
1001 * At the last moment, if this thread is still marked RUNNING,
1002 * then put it back on the run queue as it has not been suspended
1003 * or stopped or any thing else similar. We never put the idle
1004 * threads on the run queue, however.
1005 */
1006 if (td->td_flags & TDF_IDLETD) {
1007 TD_SET_CAN_RUN(td);
1008 #ifdef SMP
1009 CPU_CLR(PCPU_GET(cpuid), &idle_cpus_mask);
1010 #endif
1011 } else {
1012 if (TD_IS_RUNNING(td)) {
1013 /* Put us back on the run queue. */
1014 sched_add(td, preempted ?
1015 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
1016 SRQ_OURSELF|SRQ_YIELDING);
1017 }
1018 }
1019 if (newtd) {
1020 /*
1021 * The thread we are about to run needs to be counted
1022 * as if it had been added to the run queue and selected.
1023 * It came from:
1024 * * A preemption
1025 * * An upcall
1026 * * A followon
1027 */
1028 KASSERT((newtd->td_inhibitors == 0),
1029 ("trying to run inhibited thread"));
1030 newtd->td_flags |= TDF_DIDRUN;
1031 TD_SET_RUNNING(newtd);
1032 if ((newtd->td_flags & TDF_NOLOAD) == 0)
1033 sched_load_add();
1034 } else {
1035 newtd = choosethread();
1036 MPASS(newtd->td_lock == &sched_lock);
1037 }
1038
1039 if (td != newtd) {
1040 #ifdef HWPMC_HOOKS
1041 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1042 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
1043 #endif
1044
1045 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc);
1046
1047 /* I feel sleepy */
1048 lock_profile_release_lock(&sched_lock.lock_object);
1049 #ifdef KDTRACE_HOOKS
1050 /*
1051 * If DTrace has set the active vtime enum to anything
1052 * other than INACTIVE (0), then it should have set the
1053 * function to call.
1054 */
1055 if (dtrace_vtime_active)
1056 (*dtrace_vtime_switch_func)(newtd);
1057 #endif
1058
1059 cpu_switch(td, newtd, tmtx != NULL ? tmtx : td->td_lock);
1060 lock_profile_obtain_lock_success(&sched_lock.lock_object,
1061 0, 0, __FILE__, __LINE__);
1062 /*
1063 * Where am I? What year is it?
1064 * We are in the same thread that went to sleep above,
1065 * but any amount of time may have passed. All our context
1066 * will still be available as will local variables.
1067 * PCPU values however may have changed as we may have
1068 * changed CPU so don't trust cached values of them.
1069 * New threads will go to fork_exit() instead of here
1070 * so if you change things here you may need to change
1071 * things there too.
1072 *
1073 * If the thread above was exiting it will never wake
1074 * up again here, so either it has saved everything it
1075 * needed to, or the thread_wait() or wait() will
1076 * need to reap it.
1077 */
1078
1079 SDT_PROBE0(sched, , , on__cpu);
1080 #ifdef HWPMC_HOOKS
1081 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1082 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
1083 #endif
1084 } else
1085 SDT_PROBE0(sched, , , remain__cpu);
1086
1087 #ifdef SMP
1088 if (td->td_flags & TDF_IDLETD)
1089 CPU_SET(PCPU_GET(cpuid), &idle_cpus_mask);
1090 #endif
1091 sched_lock.mtx_lock = (uintptr_t)td;
1092 td->td_oncpu = PCPU_GET(cpuid);
1093 MPASS(td->td_lock == &sched_lock);
1094 }
1095
1096 void
1097 sched_wakeup(struct thread *td)
1098 {
1099 struct td_sched *ts;
1100
1101 THREAD_LOCK_ASSERT(td, MA_OWNED);
1102 ts = td_get_sched(td);
1103 td->td_flags &= ~TDF_CANSWAP;
1104 if (ts->ts_slptime > 1) {
1105 updatepri(td);
1106 resetpriority(td);
1107 }
1108 td->td_slptick = 0;
1109 ts->ts_slptime = 0;
1110 ts->ts_slice = sched_slice;
1111 sched_add(td, SRQ_BORING);
1112 }
1113
1114 #ifdef SMP
1115 static int
1116 forward_wakeup(int cpunum)
1117 {
1118 struct pcpu *pc;
1119 cpuset_t dontuse, map, map2;
1120 u_int id, me;
1121 int iscpuset;
1122
1123 mtx_assert(&sched_lock, MA_OWNED);
1124
1125 CTR0(KTR_RUNQ, "forward_wakeup()");
1126
1127 if ((!forward_wakeup_enabled) ||
1128 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0))
1129 return (0);
1130 if (!smp_started || cold || panicstr)
1131 return (0);
1132
1133 forward_wakeups_requested++;
1134
1135 /*
1136 * Check the idle mask we received against what we calculated
1137 * before in the old version.
1138 */
1139 me = PCPU_GET(cpuid);
1140
1141 /* Don't bother if we should be doing it ourself. */
1142 if (CPU_ISSET(me, &idle_cpus_mask) &&
1143 (cpunum == NOCPU || me == cpunum))
1144 return (0);
1145
1146 CPU_SETOF(me, &dontuse);
1147 CPU_OR(&dontuse, &stopped_cpus);
1148 CPU_OR(&dontuse, &hlt_cpus_mask);
1149 CPU_ZERO(&map2);
1150 if (forward_wakeup_use_loop) {
1151 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
1152 id = pc->pc_cpuid;
1153 if (!CPU_ISSET(id, &dontuse) &&
1154 pc->pc_curthread == pc->pc_idlethread) {
1155 CPU_SET(id, &map2);
1156 }
1157 }
1158 }
1159
1160 if (forward_wakeup_use_mask) {
1161 map = idle_cpus_mask;
1162 CPU_NAND(&map, &dontuse);
1163
1164 /* If they are both on, compare and use loop if different. */
1165 if (forward_wakeup_use_loop) {
1166 if (CPU_CMP(&map, &map2)) {
1167 printf("map != map2, loop method preferred\n");
1168 map = map2;
1169 }
1170 }
1171 } else {
1172 map = map2;
1173 }
1174
1175 /* If we only allow a specific CPU, then mask off all the others. */
1176 if (cpunum != NOCPU) {
1177 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum."));
1178 iscpuset = CPU_ISSET(cpunum, &map);
1179 if (iscpuset == 0)
1180 CPU_ZERO(&map);
1181 else
1182 CPU_SETOF(cpunum, &map);
1183 }
1184 if (!CPU_EMPTY(&map)) {
1185 forward_wakeups_delivered++;
1186 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
1187 id = pc->pc_cpuid;
1188 if (!CPU_ISSET(id, &map))
1189 continue;
1190 if (cpu_idle_wakeup(pc->pc_cpuid))
1191 CPU_CLR(id, &map);
1192 }
1193 if (!CPU_EMPTY(&map))
1194 ipi_selected(map, IPI_AST);
1195 return (1);
1196 }
1197 if (cpunum == NOCPU)
1198 printf("forward_wakeup: Idle processor not found\n");
1199 return (0);
1200 }
1201
1202 static void
1203 kick_other_cpu(int pri, int cpuid)
1204 {
1205 struct pcpu *pcpu;
1206 int cpri;
1207
1208 pcpu = pcpu_find(cpuid);
1209 if (CPU_ISSET(cpuid, &idle_cpus_mask)) {
1210 forward_wakeups_delivered++;
1211 if (!cpu_idle_wakeup(cpuid))
1212 ipi_cpu(cpuid, IPI_AST);
1213 return;
1214 }
1215
1216 cpri = pcpu->pc_curthread->td_priority;
1217 if (pri >= cpri)
1218 return;
1219
1220 #if defined(IPI_PREEMPTION) && defined(PREEMPTION)
1221 #if !defined(FULL_PREEMPTION)
1222 if (pri <= PRI_MAX_ITHD)
1223 #endif /* ! FULL_PREEMPTION */
1224 {
1225 ipi_cpu(cpuid, IPI_PREEMPT);
1226 return;
1227 }
1228 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */
1229
1230 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED;
1231 ipi_cpu(cpuid, IPI_AST);
1232 return;
1233 }
1234 #endif /* SMP */
1235
1236 #ifdef SMP
1237 static int
1238 sched_pickcpu(struct thread *td)
1239 {
1240 int best, cpu;
1241
1242 mtx_assert(&sched_lock, MA_OWNED);
1243
1244 if (td->td_lastcpu != NOCPU && THREAD_CAN_SCHED(td, td->td_lastcpu))
1245 best = td->td_lastcpu;
1246 else
1247 best = NOCPU;
1248 CPU_FOREACH(cpu) {
1249 if (!THREAD_CAN_SCHED(td, cpu))
1250 continue;
1251
1252 if (best == NOCPU)
1253 best = cpu;
1254 else if (runq_length[cpu] < runq_length[best])
1255 best = cpu;
1256 }
1257 KASSERT(best != NOCPU, ("no valid CPUs"));
1258
1259 return (best);
1260 }
1261 #endif
1262
1263 void
1264 sched_add(struct thread *td, int flags)
1265 #ifdef SMP
1266 {
1267 cpuset_t tidlemsk;
1268 struct td_sched *ts;
1269 u_int cpu, cpuid;
1270 int forwarded = 0;
1271 int single_cpu = 0;
1272
1273 ts = td_get_sched(td);
1274 THREAD_LOCK_ASSERT(td, MA_OWNED);
1275 KASSERT((td->td_inhibitors == 0),
1276 ("sched_add: trying to run inhibited thread"));
1277 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
1278 ("sched_add: bad thread state"));
1279 KASSERT(td->td_flags & TDF_INMEM,
1280 ("sched_add: thread swapped out"));
1281
1282 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
1283 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
1284 sched_tdname(curthread));
1285 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
1286 KTR_ATTR_LINKED, sched_tdname(td));
1287 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL,
1288 flags & SRQ_PREEMPTED);
1289
1290
1291 /*
1292 * Now that the thread is moving to the run-queue, set the lock
1293 * to the scheduler's lock.
1294 */
1295 if (td->td_lock != &sched_lock) {
1296 mtx_lock_spin(&sched_lock);
1297 thread_lock_set(td, &sched_lock);
1298 }
1299 TD_SET_RUNQ(td);
1300
1301 /*
1302 * If SMP is started and the thread is pinned or otherwise limited to
1303 * a specific set of CPUs, queue the thread to a per-CPU run queue.
1304 * Otherwise, queue the thread to the global run queue.
1305 *
1306 * If SMP has not yet been started we must use the global run queue
1307 * as per-CPU state may not be initialized yet and we may crash if we
1308 * try to access the per-CPU run queues.
1309 */
1310 if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND ||
1311 ts->ts_flags & TSF_AFFINITY)) {
1312 if (td->td_pinned != 0)
1313 cpu = td->td_lastcpu;
1314 else if (td->td_flags & TDF_BOUND) {
1315 /* Find CPU from bound runq. */
1316 KASSERT(SKE_RUNQ_PCPU(ts),
1317 ("sched_add: bound td_sched not on cpu runq"));
1318 cpu = ts->ts_runq - &runq_pcpu[0];
1319 } else
1320 /* Find a valid CPU for our cpuset */
1321 cpu = sched_pickcpu(td);
1322 ts->ts_runq = &runq_pcpu[cpu];
1323 single_cpu = 1;
1324 CTR3(KTR_RUNQ,
1325 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td,
1326 cpu);
1327 } else {
1328 CTR2(KTR_RUNQ,
1329 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts,
1330 td);
1331 cpu = NOCPU;
1332 ts->ts_runq = &runq;
1333 }
1334
1335 cpuid = PCPU_GET(cpuid);
1336 if (single_cpu && cpu != cpuid) {
1337 kick_other_cpu(td->td_priority, cpu);
1338 } else {
1339 if (!single_cpu) {
1340 tidlemsk = idle_cpus_mask;
1341 CPU_NAND(&tidlemsk, &hlt_cpus_mask);
1342 CPU_CLR(cpuid, &tidlemsk);
1343
1344 if (!CPU_ISSET(cpuid, &idle_cpus_mask) &&
1345 ((flags & SRQ_INTR) == 0) &&
1346 !CPU_EMPTY(&tidlemsk))
1347 forwarded = forward_wakeup(cpu);
1348 }
1349
1350 if (!forwarded) {
1351 if ((flags & SRQ_YIELDING) == 0 && maybe_preempt(td))
1352 return;
1353 else
1354 maybe_resched(td);
1355 }
1356 }
1357
1358 if ((td->td_flags & TDF_NOLOAD) == 0)
1359 sched_load_add();
1360 runq_add(ts->ts_runq, td, flags);
1361 if (cpu != NOCPU)
1362 runq_length[cpu]++;
1363 }
1364 #else /* SMP */
1365 {
1366 struct td_sched *ts;
1367
1368 ts = td_get_sched(td);
1369 THREAD_LOCK_ASSERT(td, MA_OWNED);
1370 KASSERT((td->td_inhibitors == 0),
1371 ("sched_add: trying to run inhibited thread"));
1372 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
1373 ("sched_add: bad thread state"));
1374 KASSERT(td->td_flags & TDF_INMEM,
1375 ("sched_add: thread swapped out"));
1376 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
1377 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
1378 sched_tdname(curthread));
1379 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
1380 KTR_ATTR_LINKED, sched_tdname(td));
1381 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL,
1382 flags & SRQ_PREEMPTED);
1383
1384 /*
1385 * Now that the thread is moving to the run-queue, set the lock
1386 * to the scheduler's lock.
1387 */
1388 if (td->td_lock != &sched_lock) {
1389 mtx_lock_spin(&sched_lock);
1390 thread_lock_set(td, &sched_lock);
1391 }
1392 TD_SET_RUNQ(td);
1393 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td);
1394 ts->ts_runq = &runq;
1395
1396 /*
1397 * If we are yielding (on the way out anyhow) or the thread
1398 * being saved is US, then don't try be smart about preemption
1399 * or kicking off another CPU as it won't help and may hinder.
1400 * In the YIEDLING case, we are about to run whoever is being
1401 * put in the queue anyhow, and in the OURSELF case, we are
1402 * putting ourself on the run queue which also only happens
1403 * when we are about to yield.
1404 */
1405 if ((flags & SRQ_YIELDING) == 0) {
1406 if (maybe_preempt(td))
1407 return;
1408 }
1409 if ((td->td_flags & TDF_NOLOAD) == 0)
1410 sched_load_add();
1411 runq_add(ts->ts_runq, td, flags);
1412 maybe_resched(td);
1413 }
1414 #endif /* SMP */
1415
1416 void
1417 sched_rem(struct thread *td)
1418 {
1419 struct td_sched *ts;
1420
1421 ts = td_get_sched(td);
1422 KASSERT(td->td_flags & TDF_INMEM,
1423 ("sched_rem: thread swapped out"));
1424 KASSERT(TD_ON_RUNQ(td),
1425 ("sched_rem: thread not on run queue"));
1426 mtx_assert(&sched_lock, MA_OWNED);
1427 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem",
1428 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
1429 sched_tdname(curthread));
1430 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL);
1431
1432 if ((td->td_flags & TDF_NOLOAD) == 0)
1433 sched_load_rem();
1434 #ifdef SMP
1435 if (ts->ts_runq != &runq)
1436 runq_length[ts->ts_runq - runq_pcpu]--;
1437 #endif
1438 runq_remove(ts->ts_runq, td);
1439 TD_SET_CAN_RUN(td);
1440 }
1441
1442 /*
1443 * Select threads to run. Note that running threads still consume a
1444 * slot.
1445 */
1446 struct thread *
1447 sched_choose(void)
1448 {
1449 struct thread *td;
1450 struct runq *rq;
1451
1452 mtx_assert(&sched_lock, MA_OWNED);
1453 #ifdef SMP
1454 struct thread *tdcpu;
1455
1456 rq = &runq;
1457 td = runq_choose_fuzz(&runq, runq_fuzz);
1458 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]);
1459
1460 if (td == NULL ||
1461 (tdcpu != NULL &&
1462 tdcpu->td_priority < td->td_priority)) {
1463 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu,
1464 PCPU_GET(cpuid));
1465 td = tdcpu;
1466 rq = &runq_pcpu[PCPU_GET(cpuid)];
1467 } else {
1468 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td);
1469 }
1470
1471 #else
1472 rq = &runq;
1473 td = runq_choose(&runq);
1474 #endif
1475
1476 if (td) {
1477 #ifdef SMP
1478 if (td == tdcpu)
1479 runq_length[PCPU_GET(cpuid)]--;
1480 #endif
1481 runq_remove(rq, td);
1482 td->td_flags |= TDF_DIDRUN;
1483
1484 KASSERT(td->td_flags & TDF_INMEM,
1485 ("sched_choose: thread swapped out"));
1486 return (td);
1487 }
1488 return (PCPU_GET(idlethread));
1489 }
1490
1491 void
1492 sched_preempt(struct thread *td)
1493 {
1494
1495 SDT_PROBE2(sched, , , surrender, td, td->td_proc);
1496 thread_lock(td);
1497 if (td->td_critnest > 1)
1498 td->td_owepreempt = 1;
1499 else
1500 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, NULL);
1501 thread_unlock(td);
1502 }
1503
1504 void
1505 sched_userret(struct thread *td)
1506 {
1507 /*
1508 * XXX we cheat slightly on the locking here to avoid locking in
1509 * the usual case. Setting td_priority here is essentially an
1510 * incomplete workaround for not setting it properly elsewhere.
1511 * Now that some interrupt handlers are threads, not setting it
1512 * properly elsewhere can clobber it in the window between setting
1513 * it here and returning to user mode, so don't waste time setting
1514 * it perfectly here.
1515 */
1516 KASSERT((td->td_flags & TDF_BORROWING) == 0,
1517 ("thread with borrowed priority returning to userland"));
1518 if (td->td_priority != td->td_user_pri) {
1519 thread_lock(td);
1520 td->td_priority = td->td_user_pri;
1521 td->td_base_pri = td->td_user_pri;
1522 thread_unlock(td);
1523 }
1524 }
1525
1526 void
1527 sched_bind(struct thread *td, int cpu)
1528 {
1529 struct td_sched *ts;
1530
1531 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED);
1532 KASSERT(td == curthread, ("sched_bind: can only bind curthread"));
1533
1534 ts = td_get_sched(td);
1535
1536 td->td_flags |= TDF_BOUND;
1537 #ifdef SMP
1538 ts->ts_runq = &runq_pcpu[cpu];
1539 if (PCPU_GET(cpuid) == cpu)
1540 return;
1541
1542 mi_switch(SW_VOL, NULL);
1543 #endif
1544 }
1545
1546 void
1547 sched_unbind(struct thread* td)
1548 {
1549 THREAD_LOCK_ASSERT(td, MA_OWNED);
1550 KASSERT(td == curthread, ("sched_unbind: can only bind curthread"));
1551 td->td_flags &= ~TDF_BOUND;
1552 }
1553
1554 int
1555 sched_is_bound(struct thread *td)
1556 {
1557 THREAD_LOCK_ASSERT(td, MA_OWNED);
1558 return (td->td_flags & TDF_BOUND);
1559 }
1560
1561 void
1562 sched_relinquish(struct thread *td)
1563 {
1564 thread_lock(td);
1565 mi_switch(SW_VOL | SWT_RELINQUISH, NULL);
1566 thread_unlock(td);
1567 }
1568
1569 int
1570 sched_load(void)
1571 {
1572 return (sched_tdcnt);
1573 }
1574
1575 int
1576 sched_sizeof_proc(void)
1577 {
1578 return (sizeof(struct proc));
1579 }
1580
1581 int
1582 sched_sizeof_thread(void)
1583 {
1584 return (sizeof(struct thread) + sizeof(struct td_sched));
1585 }
1586
1587 fixpt_t
1588 sched_pctcpu(struct thread *td)
1589 {
1590 struct td_sched *ts;
1591
1592 THREAD_LOCK_ASSERT(td, MA_OWNED);
1593 ts = td_get_sched(td);
1594 return (ts->ts_pctcpu);
1595 }
1596
1597 #ifdef RACCT
1598 /*
1599 * Calculates the contribution to the thread cpu usage for the latest
1600 * (unfinished) second.
1601 */
1602 fixpt_t
1603 sched_pctcpu_delta(struct thread *td)
1604 {
1605 struct td_sched *ts;
1606 fixpt_t delta;
1607 int realstathz;
1608
1609 THREAD_LOCK_ASSERT(td, MA_OWNED);
1610 ts = td_get_sched(td);
1611 delta = 0;
1612 realstathz = stathz ? stathz : hz;
1613 if (ts->ts_cpticks != 0) {
1614 #if (FSHIFT >= CCPU_SHIFT)
1615 delta = (realstathz == 100)
1616 ? ((fixpt_t) ts->ts_cpticks) <<
1617 (FSHIFT - CCPU_SHIFT) :
1618 100 * (((fixpt_t) ts->ts_cpticks)
1619 << (FSHIFT - CCPU_SHIFT)) / realstathz;
1620 #else
1621 delta = ((FSCALE - ccpu) *
1622 (ts->ts_cpticks *
1623 FSCALE / realstathz)) >> FSHIFT;
1624 #endif
1625 }
1626
1627 return (delta);
1628 }
1629 #endif
1630
1631 u_int
1632 sched_estcpu(struct thread *td)
1633 {
1634
1635 return (td_get_sched(td)->ts_estcpu);
1636 }
1637
1638 /*
1639 * The actual idle process.
1640 */
1641 void
1642 sched_idletd(void *dummy)
1643 {
1644 struct pcpuidlestat *stat;
1645
1646 THREAD_NO_SLEEPING();
1647 stat = DPCPU_PTR(idlestat);
1648 for (;;) {
1649 mtx_assert(&Giant, MA_NOTOWNED);
1650
1651 while (sched_runnable() == 0) {
1652 cpu_idle(stat->idlecalls + stat->oldidlecalls > 64);
1653 stat->idlecalls++;
1654 }
1655
1656 mtx_lock_spin(&sched_lock);
1657 mi_switch(SW_VOL | SWT_IDLE, NULL);
1658 mtx_unlock_spin(&sched_lock);
1659 }
1660 }
1661
1662 /*
1663 * A CPU is entering for the first time or a thread is exiting.
1664 */
1665 void
1666 sched_throw(struct thread *td)
1667 {
1668 /*
1669 * Correct spinlock nesting. The idle thread context that we are
1670 * borrowing was created so that it would start out with a single
1671 * spin lock (sched_lock) held in fork_trampoline(). Since we've
1672 * explicitly acquired locks in this function, the nesting count
1673 * is now 2 rather than 1. Since we are nested, calling
1674 * spinlock_exit() will simply adjust the counts without allowing
1675 * spin lock using code to interrupt us.
1676 */
1677 if (td == NULL) {
1678 mtx_lock_spin(&sched_lock);
1679 spinlock_exit();
1680 PCPU_SET(switchtime, cpu_ticks());
1681 PCPU_SET(switchticks, ticks);
1682 } else {
1683 lock_profile_release_lock(&sched_lock.lock_object);
1684 MPASS(td->td_lock == &sched_lock);
1685 td->td_lastcpu = td->td_oncpu;
1686 td->td_oncpu = NOCPU;
1687 }
1688 mtx_assert(&sched_lock, MA_OWNED);
1689 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count"));
1690 cpu_throw(td, choosethread()); /* doesn't return */
1691 }
1692
1693 void
1694 sched_fork_exit(struct thread *td)
1695 {
1696
1697 /*
1698 * Finish setting up thread glue so that it begins execution in a
1699 * non-nested critical section with sched_lock held but not recursed.
1700 */
1701 td->td_oncpu = PCPU_GET(cpuid);
1702 sched_lock.mtx_lock = (uintptr_t)td;
1703 lock_profile_obtain_lock_success(&sched_lock.lock_object,
1704 0, 0, __FILE__, __LINE__);
1705 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED);
1706 }
1707
1708 char *
1709 sched_tdname(struct thread *td)
1710 {
1711 #ifdef KTR
1712 struct td_sched *ts;
1713
1714 ts = td_get_sched(td);
1715 if (ts->ts_name[0] == '\0')
1716 snprintf(ts->ts_name, sizeof(ts->ts_name),
1717 "%s tid %d", td->td_name, td->td_tid);
1718 return (ts->ts_name);
1719 #else
1720 return (td->td_name);
1721 #endif
1722 }
1723
1724 #ifdef KTR
1725 void
1726 sched_clear_tdname(struct thread *td)
1727 {
1728 struct td_sched *ts;
1729
1730 ts = td_get_sched(td);
1731 ts->ts_name[0] = '\0';
1732 }
1733 #endif
1734
1735 void
1736 sched_affinity(struct thread *td)
1737 {
1738 #ifdef SMP
1739 struct td_sched *ts;
1740 int cpu;
1741
1742 THREAD_LOCK_ASSERT(td, MA_OWNED);
1743
1744 /*
1745 * Set the TSF_AFFINITY flag if there is at least one CPU this
1746 * thread can't run on.
1747 */
1748 ts = td_get_sched(td);
1749 ts->ts_flags &= ~TSF_AFFINITY;
1750 CPU_FOREACH(cpu) {
1751 if (!THREAD_CAN_SCHED(td, cpu)) {
1752 ts->ts_flags |= TSF_AFFINITY;
1753 break;
1754 }
1755 }
1756
1757 /*
1758 * If this thread can run on all CPUs, nothing else to do.
1759 */
1760 if (!(ts->ts_flags & TSF_AFFINITY))
1761 return;
1762
1763 /* Pinned threads and bound threads should be left alone. */
1764 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND)
1765 return;
1766
1767 switch (td->td_state) {
1768 case TDS_RUNQ:
1769 /*
1770 * If we are on a per-CPU runqueue that is in the set,
1771 * then nothing needs to be done.
1772 */
1773 if (ts->ts_runq != &runq &&
1774 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu))
1775 return;
1776
1777 /* Put this thread on a valid per-CPU runqueue. */
1778 sched_rem(td);
1779 sched_add(td, SRQ_BORING);
1780 break;
1781 case TDS_RUNNING:
1782 /*
1783 * See if our current CPU is in the set. If not, force a
1784 * context switch.
1785 */
1786 if (THREAD_CAN_SCHED(td, td->td_oncpu))
1787 return;
1788
1789 td->td_flags |= TDF_NEEDRESCHED;
1790 if (td != curthread)
1791 ipi_cpu(cpu, IPI_AST);
1792 break;
1793 default:
1794 break;
1795 }
1796 #endif
1797 }
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