FreeBSD/Linux Kernel Cross Reference
sys/kern/sched_4bsd.c
1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1982, 1986, 1990, 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 * (c) UNIX System Laboratories, Inc.
7 * All or some portions of this file are derived from material licensed
8 * to the University of California by American Telephone and Telegraph
9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
10 * the permission of UNIX System Laboratories, Inc.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD: releng/12.0/sys/kern/sched_4bsd.c 336007 2018-07-05 17:13:37Z andrew $");
39
40 #include "opt_hwpmc_hooks.h"
41 #include "opt_sched.h"
42
43 #include <sys/param.h>
44 #include <sys/systm.h>
45 #include <sys/cpuset.h>
46 #include <sys/kernel.h>
47 #include <sys/ktr.h>
48 #include <sys/lock.h>
49 #include <sys/kthread.h>
50 #include <sys/mutex.h>
51 #include <sys/proc.h>
52 #include <sys/resourcevar.h>
53 #include <sys/sched.h>
54 #include <sys/sdt.h>
55 #include <sys/smp.h>
56 #include <sys/sysctl.h>
57 #include <sys/sx.h>
58 #include <sys/turnstile.h>
59 #include <sys/umtx.h>
60 #include <machine/pcb.h>
61 #include <machine/smp.h>
62
63 #ifdef HWPMC_HOOKS
64 #include <sys/pmckern.h>
65 #endif
66
67 #ifdef KDTRACE_HOOKS
68 #include <sys/dtrace_bsd.h>
69 int dtrace_vtime_active;
70 dtrace_vtime_switch_func_t dtrace_vtime_switch_func;
71 #endif
72
73 /*
74 * INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in
75 * the range 100-256 Hz (approximately).
76 */
77 #define ESTCPULIM(e) \
78 min((e), INVERSE_ESTCPU_WEIGHT * (NICE_WEIGHT * (PRIO_MAX - PRIO_MIN) - \
79 RQ_PPQ) + INVERSE_ESTCPU_WEIGHT - 1)
80 #ifdef SMP
81 #define INVERSE_ESTCPU_WEIGHT (8 * smp_cpus)
82 #else
83 #define INVERSE_ESTCPU_WEIGHT 8 /* 1 / (priorities per estcpu level). */
84 #endif
85 #define NICE_WEIGHT 1 /* Priorities per nice level. */
86
87 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX)))
88
89 /*
90 * The schedulable entity that runs a context.
91 * This is an extension to the thread structure and is tailored to
92 * the requirements of this scheduler.
93 * All fields are protected by the scheduler lock.
94 */
95 struct td_sched {
96 fixpt_t ts_pctcpu; /* %cpu during p_swtime. */
97 u_int ts_estcpu; /* Estimated cpu utilization. */
98 int ts_cpticks; /* Ticks of cpu time. */
99 int ts_slptime; /* Seconds !RUNNING. */
100 int ts_slice; /* Remaining part of time slice. */
101 int ts_flags;
102 struct runq *ts_runq; /* runq the thread is currently on */
103 #ifdef KTR
104 char ts_name[TS_NAME_LEN];
105 #endif
106 };
107
108 /* flags kept in td_flags */
109 #define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */
110 #define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */
111 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */
112
113 /* flags kept in ts_flags */
114 #define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */
115
116 #define SKE_RUNQ_PCPU(ts) \
117 ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq)
118
119 #define THREAD_CAN_SCHED(td, cpu) \
120 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask)
121
122 _Static_assert(sizeof(struct thread) + sizeof(struct td_sched) <=
123 sizeof(struct thread0_storage),
124 "increase struct thread0_storage.t0st_sched size");
125
126 static struct mtx sched_lock;
127
128 static int realstathz = 127; /* stathz is sometimes 0 and run off of hz. */
129 static int sched_tdcnt; /* Total runnable threads in the system. */
130 static int sched_slice = 12; /* Thread run time before rescheduling. */
131
132 static void setup_runqs(void);
133 static void schedcpu(void);
134 static void schedcpu_thread(void);
135 static void sched_priority(struct thread *td, u_char prio);
136 static void sched_setup(void *dummy);
137 static void maybe_resched(struct thread *td);
138 static void updatepri(struct thread *td);
139 static void resetpriority(struct thread *td);
140 static void resetpriority_thread(struct thread *td);
141 #ifdef SMP
142 static int sched_pickcpu(struct thread *td);
143 static int forward_wakeup(int cpunum);
144 static void kick_other_cpu(int pri, int cpuid);
145 #endif
146
147 static struct kproc_desc sched_kp = {
148 "schedcpu",
149 schedcpu_thread,
150 NULL
151 };
152 SYSINIT(schedcpu, SI_SUB_LAST, SI_ORDER_FIRST, kproc_start,
153 &sched_kp);
154 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL);
155
156 static void sched_initticks(void *dummy);
157 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks,
158 NULL);
159
160 /*
161 * Global run queue.
162 */
163 static struct runq runq;
164
165 #ifdef SMP
166 /*
167 * Per-CPU run queues
168 */
169 static struct runq runq_pcpu[MAXCPU];
170 long runq_length[MAXCPU];
171
172 static cpuset_t idle_cpus_mask;
173 #endif
174
175 struct pcpuidlestat {
176 u_int idlecalls;
177 u_int oldidlecalls;
178 };
179 DPCPU_DEFINE_STATIC(struct pcpuidlestat, idlestat);
180
181 static void
182 setup_runqs(void)
183 {
184 #ifdef SMP
185 int i;
186
187 for (i = 0; i < MAXCPU; ++i)
188 runq_init(&runq_pcpu[i]);
189 #endif
190
191 runq_init(&runq);
192 }
193
194 static int
195 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
196 {
197 int error, new_val, period;
198
199 period = 1000000 / realstathz;
200 new_val = period * sched_slice;
201 error = sysctl_handle_int(oidp, &new_val, 0, req);
202 if (error != 0 || req->newptr == NULL)
203 return (error);
204 if (new_val <= 0)
205 return (EINVAL);
206 sched_slice = imax(1, (new_val + period / 2) / period);
207 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
208 realstathz);
209 return (0);
210 }
211
212 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler");
213
214 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0,
215 "Scheduler name");
216 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW,
217 NULL, 0, sysctl_kern_quantum, "I",
218 "Quantum for timeshare threads in microseconds");
219 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
220 "Quantum for timeshare threads in stathz ticks");
221 #ifdef SMP
222 /* Enable forwarding of wakeups to all other cpus */
223 static SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL,
224 "Kernel SMP");
225
226 static int runq_fuzz = 1;
227 SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, "");
228
229 static int forward_wakeup_enabled = 1;
230 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW,
231 &forward_wakeup_enabled, 0,
232 "Forwarding of wakeup to idle CPUs");
233
234 static int forward_wakeups_requested = 0;
235 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD,
236 &forward_wakeups_requested, 0,
237 "Requests for Forwarding of wakeup to idle CPUs");
238
239 static int forward_wakeups_delivered = 0;
240 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD,
241 &forward_wakeups_delivered, 0,
242 "Completed Forwarding of wakeup to idle CPUs");
243
244 static int forward_wakeup_use_mask = 1;
245 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW,
246 &forward_wakeup_use_mask, 0,
247 "Use the mask of idle cpus");
248
249 static int forward_wakeup_use_loop = 0;
250 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW,
251 &forward_wakeup_use_loop, 0,
252 "Use a loop to find idle cpus");
253
254 #endif
255 #if 0
256 static int sched_followon = 0;
257 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW,
258 &sched_followon, 0,
259 "allow threads to share a quantum");
260 #endif
261
262 SDT_PROVIDER_DEFINE(sched);
263
264 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *",
265 "struct proc *", "uint8_t");
266 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *",
267 "struct proc *", "void *");
268 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *",
269 "struct proc *", "void *", "int");
270 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *",
271 "struct proc *", "uint8_t", "struct thread *");
272 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int");
273 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *",
274 "struct proc *");
275 SDT_PROBE_DEFINE(sched, , , on__cpu);
276 SDT_PROBE_DEFINE(sched, , , remain__cpu);
277 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *",
278 "struct proc *");
279
280 static __inline void
281 sched_load_add(void)
282 {
283
284 sched_tdcnt++;
285 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt);
286 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt);
287 }
288
289 static __inline void
290 sched_load_rem(void)
291 {
292
293 sched_tdcnt--;
294 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt);
295 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt);
296 }
297 /*
298 * Arrange to reschedule if necessary, taking the priorities and
299 * schedulers into account.
300 */
301 static void
302 maybe_resched(struct thread *td)
303 {
304
305 THREAD_LOCK_ASSERT(td, MA_OWNED);
306 if (td->td_priority < curthread->td_priority)
307 curthread->td_flags |= TDF_NEEDRESCHED;
308 }
309
310 /*
311 * This function is called when a thread is about to be put on run queue
312 * because it has been made runnable or its priority has been adjusted. It
313 * determines if the new thread should preempt the current thread. If so,
314 * it sets td_owepreempt to request a preemption.
315 */
316 int
317 maybe_preempt(struct thread *td)
318 {
319 #ifdef PREEMPTION
320 struct thread *ctd;
321 int cpri, pri;
322
323 /*
324 * The new thread should not preempt the current thread if any of the
325 * following conditions are true:
326 *
327 * - The kernel is in the throes of crashing (panicstr).
328 * - The current thread has a higher (numerically lower) or
329 * equivalent priority. Note that this prevents curthread from
330 * trying to preempt to itself.
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 /* || 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 CTR0(KTR_PROC, "maybe_preempt: scheduling preemption");
360 ctd->td_owepreempt = 1;
361 return (1);
362 #else
363 return (0);
364 #endif
365 }
366
367 /*
368 * Constants for digital decay and forget:
369 * 90% of (ts_estcpu) usage in 5 * loadav time
370 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive)
371 * Note that, as ps(1) mentions, this can let percentages
372 * total over 100% (I've seen 137.9% for 3 processes).
373 *
374 * Note that schedclock() updates ts_estcpu and p_cpticks asynchronously.
375 *
376 * We wish to decay away 90% of ts_estcpu in (5 * loadavg) seconds.
377 * That is, the system wants to compute a value of decay such
378 * that the following for loop:
379 * for (i = 0; i < (5 * loadavg); i++)
380 * ts_estcpu *= decay;
381 * will compute
382 * ts_estcpu *= 0.1;
383 * for all values of loadavg:
384 *
385 * Mathematically this loop can be expressed by saying:
386 * decay ** (5 * loadavg) ~= .1
387 *
388 * The system computes decay as:
389 * decay = (2 * loadavg) / (2 * loadavg + 1)
390 *
391 * We wish to prove that the system's computation of decay
392 * will always fulfill the equation:
393 * decay ** (5 * loadavg) ~= .1
394 *
395 * If we compute b as:
396 * b = 2 * loadavg
397 * then
398 * decay = b / (b + 1)
399 *
400 * We now need to prove two things:
401 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1)
402 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg)
403 *
404 * Facts:
405 * For x close to zero, exp(x) =~ 1 + x, since
406 * exp(x) = 0! + x**1/1! + x**2/2! + ... .
407 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b.
408 * For x close to zero, ln(1+x) =~ x, since
409 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1
410 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1).
411 * ln(.1) =~ -2.30
412 *
413 * Proof of (1):
414 * Solve (factor)**(power) =~ .1 given power (5*loadav):
415 * solving for factor,
416 * ln(factor) =~ (-2.30/5*loadav), or
417 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) =
418 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED
419 *
420 * Proof of (2):
421 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)):
422 * solving for power,
423 * power*ln(b/(b+1)) =~ -2.30, or
424 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED
425 *
426 * Actual power values for the implemented algorithm are as follows:
427 * loadav: 1 2 3 4
428 * power: 5.68 10.32 14.94 19.55
429 */
430
431 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */
432 #define loadfactor(loadav) (2 * (loadav))
433 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE))
434
435 /* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */
436 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
437 SYSCTL_UINT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");
438
439 /*
440 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the
441 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below
442 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT).
443 *
444 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used:
445 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits).
446 *
447 * If you don't want to bother with the faster/more-accurate formula, you
448 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate
449 * (more general) method of calculating the %age of CPU used by a process.
450 */
451 #define CCPU_SHIFT 11
452
453 /*
454 * Recompute process priorities, every hz ticks.
455 * MP-safe, called without the Giant mutex.
456 */
457 /* ARGSUSED */
458 static void
459 schedcpu(void)
460 {
461 fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
462 struct thread *td;
463 struct proc *p;
464 struct td_sched *ts;
465 int awake;
466
467 sx_slock(&allproc_lock);
468 FOREACH_PROC_IN_SYSTEM(p) {
469 PROC_LOCK(p);
470 if (p->p_state == PRS_NEW) {
471 PROC_UNLOCK(p);
472 continue;
473 }
474 FOREACH_THREAD_IN_PROC(p, td) {
475 awake = 0;
476 ts = td_get_sched(td);
477 thread_lock(td);
478 /*
479 * Increment sleep time (if sleeping). We
480 * ignore overflow, as above.
481 */
482 /*
483 * The td_sched slptimes are not touched in wakeup
484 * because the thread may not HAVE everything in
485 * memory? XXX I think this is out of date.
486 */
487 if (TD_ON_RUNQ(td)) {
488 awake = 1;
489 td->td_flags &= ~TDF_DIDRUN;
490 } else if (TD_IS_RUNNING(td)) {
491 awake = 1;
492 /* Do not clear TDF_DIDRUN */
493 } else if (td->td_flags & TDF_DIDRUN) {
494 awake = 1;
495 td->td_flags &= ~TDF_DIDRUN;
496 }
497
498 /*
499 * ts_pctcpu is only for ps and ttyinfo().
500 */
501 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT;
502 /*
503 * If the td_sched has been idle the entire second,
504 * stop recalculating its priority until
505 * it wakes up.
506 */
507 if (ts->ts_cpticks != 0) {
508 #if (FSHIFT >= CCPU_SHIFT)
509 ts->ts_pctcpu += (realstathz == 100)
510 ? ((fixpt_t) ts->ts_cpticks) <<
511 (FSHIFT - CCPU_SHIFT) :
512 100 * (((fixpt_t) ts->ts_cpticks)
513 << (FSHIFT - CCPU_SHIFT)) / realstathz;
514 #else
515 ts->ts_pctcpu += ((FSCALE - ccpu) *
516 (ts->ts_cpticks *
517 FSCALE / realstathz)) >> FSHIFT;
518 #endif
519 ts->ts_cpticks = 0;
520 }
521 /*
522 * If there are ANY running threads in this process,
523 * then don't count it as sleeping.
524 * XXX: this is broken.
525 */
526 if (awake) {
527 if (ts->ts_slptime > 1) {
528 /*
529 * In an ideal world, this should not
530 * happen, because whoever woke us
531 * up from the long sleep should have
532 * unwound the slptime and reset our
533 * priority before we run at the stale
534 * priority. Should KASSERT at some
535 * point when all the cases are fixed.
536 */
537 updatepri(td);
538 }
539 ts->ts_slptime = 0;
540 } else
541 ts->ts_slptime++;
542 if (ts->ts_slptime > 1) {
543 thread_unlock(td);
544 continue;
545 }
546 ts->ts_estcpu = decay_cpu(loadfac, ts->ts_estcpu);
547 resetpriority(td);
548 resetpriority_thread(td);
549 thread_unlock(td);
550 }
551 PROC_UNLOCK(p);
552 }
553 sx_sunlock(&allproc_lock);
554 }
555
556 /*
557 * Main loop for a kthread that executes schedcpu once a second.
558 */
559 static void
560 schedcpu_thread(void)
561 {
562
563 for (;;) {
564 schedcpu();
565 pause("-", hz);
566 }
567 }
568
569 /*
570 * Recalculate the priority of a process after it has slept for a while.
571 * For all load averages >= 1 and max ts_estcpu of 255, sleeping for at
572 * least six times the loadfactor will decay ts_estcpu to zero.
573 */
574 static void
575 updatepri(struct thread *td)
576 {
577 struct td_sched *ts;
578 fixpt_t loadfac;
579 unsigned int newcpu;
580
581 ts = td_get_sched(td);
582 loadfac = loadfactor(averunnable.ldavg[0]);
583 if (ts->ts_slptime > 5 * loadfac)
584 ts->ts_estcpu = 0;
585 else {
586 newcpu = ts->ts_estcpu;
587 ts->ts_slptime--; /* was incremented in schedcpu() */
588 while (newcpu && --ts->ts_slptime)
589 newcpu = decay_cpu(loadfac, newcpu);
590 ts->ts_estcpu = newcpu;
591 }
592 }
593
594 /*
595 * Compute the priority of a process when running in user mode.
596 * Arrange to reschedule if the resulting priority is better
597 * than that of the current process.
598 */
599 static void
600 resetpriority(struct thread *td)
601 {
602 u_int newpriority;
603
604 if (td->td_pri_class != PRI_TIMESHARE)
605 return;
606 newpriority = PUSER +
607 td_get_sched(td)->ts_estcpu / INVERSE_ESTCPU_WEIGHT +
608 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN);
609 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE),
610 PRI_MAX_TIMESHARE);
611 sched_user_prio(td, newpriority);
612 }
613
614 /*
615 * Update the thread's priority when the associated process's user
616 * priority changes.
617 */
618 static void
619 resetpriority_thread(struct thread *td)
620 {
621
622 /* Only change threads with a time sharing user priority. */
623 if (td->td_priority < PRI_MIN_TIMESHARE ||
624 td->td_priority > PRI_MAX_TIMESHARE)
625 return;
626
627 /* XXX the whole needresched thing is broken, but not silly. */
628 maybe_resched(td);
629
630 sched_prio(td, td->td_user_pri);
631 }
632
633 /* ARGSUSED */
634 static void
635 sched_setup(void *dummy)
636 {
637
638 setup_runqs();
639
640 /* Account for thread0. */
641 sched_load_add();
642 }
643
644 /*
645 * This routine determines time constants after stathz and hz are setup.
646 */
647 static void
648 sched_initticks(void *dummy)
649 {
650
651 realstathz = stathz ? stathz : hz;
652 sched_slice = realstathz / 10; /* ~100ms */
653 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
654 realstathz);
655 }
656
657 /* External interfaces start here */
658
659 /*
660 * Very early in the boot some setup of scheduler-specific
661 * parts of proc0 and of some scheduler resources needs to be done.
662 * Called from:
663 * proc0_init()
664 */
665 void
666 schedinit(void)
667 {
668
669 /*
670 * Set up the scheduler specific parts of thread0.
671 */
672 thread0.td_lock = &sched_lock;
673 td_get_sched(&thread0)->ts_slice = sched_slice;
674 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE);
675 }
676
677 int
678 sched_runnable(void)
679 {
680 #ifdef SMP
681 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]);
682 #else
683 return runq_check(&runq);
684 #endif
685 }
686
687 int
688 sched_rr_interval(void)
689 {
690
691 /* Convert sched_slice from stathz to hz. */
692 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz));
693 }
694
695 /*
696 * We adjust the priority of the current process. The priority of a
697 * process gets worse as it accumulates CPU time. The cpu usage
698 * estimator (ts_estcpu) is increased here. resetpriority() will
699 * compute a different priority each time ts_estcpu increases by
700 * INVERSE_ESTCPU_WEIGHT (until PRI_MAX_TIMESHARE is reached). The
701 * cpu usage estimator ramps up quite quickly when the process is
702 * running (linearly), and decays away exponentially, at a rate which
703 * is proportionally slower when the system is busy. The basic
704 * principle is that the system will 90% forget that the process used
705 * a lot of CPU time in 5 * loadav seconds. This causes the system to
706 * favor processes which haven't run much recently, and to round-robin
707 * among other processes.
708 */
709 void
710 sched_clock(struct thread *td)
711 {
712 struct pcpuidlestat *stat;
713 struct td_sched *ts;
714
715 THREAD_LOCK_ASSERT(td, MA_OWNED);
716 ts = td_get_sched(td);
717
718 ts->ts_cpticks++;
719 ts->ts_estcpu = ESTCPULIM(ts->ts_estcpu + 1);
720 if ((ts->ts_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) {
721 resetpriority(td);
722 resetpriority_thread(td);
723 }
724
725 /*
726 * Force a context switch if the current thread has used up a full
727 * time slice (default is 100ms).
728 */
729 if (!TD_IS_IDLETHREAD(td) && --ts->ts_slice <= 0) {
730 ts->ts_slice = sched_slice;
731 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND;
732 }
733
734 stat = DPCPU_PTR(idlestat);
735 stat->oldidlecalls = stat->idlecalls;
736 stat->idlecalls = 0;
737 }
738
739 /*
740 * Charge child's scheduling CPU usage to parent.
741 */
742 void
743 sched_exit(struct proc *p, struct thread *td)
744 {
745
746 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit",
747 "prio:%d", td->td_priority);
748
749 PROC_LOCK_ASSERT(p, MA_OWNED);
750 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td);
751 }
752
753 void
754 sched_exit_thread(struct thread *td, struct thread *child)
755 {
756
757 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit",
758 "prio:%d", child->td_priority);
759 thread_lock(td);
760 td_get_sched(td)->ts_estcpu = ESTCPULIM(td_get_sched(td)->ts_estcpu +
761 td_get_sched(child)->ts_estcpu);
762 thread_unlock(td);
763 thread_lock(child);
764 if ((child->td_flags & TDF_NOLOAD) == 0)
765 sched_load_rem();
766 thread_unlock(child);
767 }
768
769 void
770 sched_fork(struct thread *td, struct thread *childtd)
771 {
772 sched_fork_thread(td, childtd);
773 }
774
775 void
776 sched_fork_thread(struct thread *td, struct thread *childtd)
777 {
778 struct td_sched *ts, *tsc;
779
780 childtd->td_oncpu = NOCPU;
781 childtd->td_lastcpu = NOCPU;
782 childtd->td_lock = &sched_lock;
783 childtd->td_cpuset = cpuset_ref(td->td_cpuset);
784 childtd->td_domain.dr_policy = td->td_cpuset->cs_domain;
785 childtd->td_priority = childtd->td_base_pri;
786 ts = td_get_sched(childtd);
787 bzero(ts, sizeof(*ts));
788 tsc = td_get_sched(td);
789 ts->ts_estcpu = tsc->ts_estcpu;
790 ts->ts_flags |= (tsc->ts_flags & TSF_AFFINITY);
791 ts->ts_slice = 1;
792 }
793
794 void
795 sched_nice(struct proc *p, int nice)
796 {
797 struct thread *td;
798
799 PROC_LOCK_ASSERT(p, MA_OWNED);
800 p->p_nice = nice;
801 FOREACH_THREAD_IN_PROC(p, td) {
802 thread_lock(td);
803 resetpriority(td);
804 resetpriority_thread(td);
805 thread_unlock(td);
806 }
807 }
808
809 void
810 sched_class(struct thread *td, int class)
811 {
812 THREAD_LOCK_ASSERT(td, MA_OWNED);
813 td->td_pri_class = class;
814 }
815
816 /*
817 * Adjust the priority of a thread.
818 */
819 static void
820 sched_priority(struct thread *td, u_char prio)
821 {
822
823
824 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change",
825 "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED,
826 sched_tdname(curthread));
827 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio);
828 if (td != curthread && prio > td->td_priority) {
829 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread),
830 "lend prio", "prio:%d", td->td_priority, "new prio:%d",
831 prio, KTR_ATTR_LINKED, sched_tdname(td));
832 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio,
833 curthread);
834 }
835 THREAD_LOCK_ASSERT(td, MA_OWNED);
836 if (td->td_priority == prio)
837 return;
838 td->td_priority = prio;
839 if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) {
840 sched_rem(td);
841 sched_add(td, SRQ_BORING);
842 }
843 }
844
845 /*
846 * Update a thread's priority when it is lent another thread's
847 * priority.
848 */
849 void
850 sched_lend_prio(struct thread *td, u_char prio)
851 {
852
853 td->td_flags |= TDF_BORROWING;
854 sched_priority(td, prio);
855 }
856
857 /*
858 * Restore a thread's priority when priority propagation is
859 * over. The prio argument is the minimum priority the thread
860 * needs to have to satisfy other possible priority lending
861 * requests. If the thread's regulary priority is less
862 * important than prio the thread will keep a priority boost
863 * of prio.
864 */
865 void
866 sched_unlend_prio(struct thread *td, u_char prio)
867 {
868 u_char base_pri;
869
870 if (td->td_base_pri >= PRI_MIN_TIMESHARE &&
871 td->td_base_pri <= PRI_MAX_TIMESHARE)
872 base_pri = td->td_user_pri;
873 else
874 base_pri = td->td_base_pri;
875 if (prio >= base_pri) {
876 td->td_flags &= ~TDF_BORROWING;
877 sched_prio(td, base_pri);
878 } else
879 sched_lend_prio(td, prio);
880 }
881
882 void
883 sched_prio(struct thread *td, u_char prio)
884 {
885 u_char oldprio;
886
887 /* First, update the base priority. */
888 td->td_base_pri = prio;
889
890 /*
891 * If the thread is borrowing another thread's priority, don't ever
892 * lower the priority.
893 */
894 if (td->td_flags & TDF_BORROWING && td->td_priority < prio)
895 return;
896
897 /* Change the real priority. */
898 oldprio = td->td_priority;
899 sched_priority(td, prio);
900
901 /*
902 * If the thread is on a turnstile, then let the turnstile update
903 * its state.
904 */
905 if (TD_ON_LOCK(td) && oldprio != prio)
906 turnstile_adjust(td, oldprio);
907 }
908
909 void
910 sched_user_prio(struct thread *td, u_char prio)
911 {
912
913 THREAD_LOCK_ASSERT(td, MA_OWNED);
914 td->td_base_user_pri = prio;
915 if (td->td_lend_user_pri <= prio)
916 return;
917 td->td_user_pri = prio;
918 }
919
920 void
921 sched_lend_user_prio(struct thread *td, u_char prio)
922 {
923
924 THREAD_LOCK_ASSERT(td, MA_OWNED);
925 td->td_lend_user_pri = prio;
926 td->td_user_pri = min(prio, td->td_base_user_pri);
927 if (td->td_priority > td->td_user_pri)
928 sched_prio(td, td->td_user_pri);
929 else if (td->td_priority != td->td_user_pri)
930 td->td_flags |= TDF_NEEDRESCHED;
931 }
932
933 void
934 sched_sleep(struct thread *td, int pri)
935 {
936
937 THREAD_LOCK_ASSERT(td, MA_OWNED);
938 td->td_slptick = ticks;
939 td_get_sched(td)->ts_slptime = 0;
940 if (pri != 0 && PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
941 sched_prio(td, pri);
942 if (TD_IS_SUSPENDED(td) || pri >= PSOCK)
943 td->td_flags |= TDF_CANSWAP;
944 }
945
946 void
947 sched_switch(struct thread *td, struct thread *newtd, int flags)
948 {
949 struct mtx *tmtx;
950 struct td_sched *ts;
951 struct proc *p;
952 int preempted;
953
954 tmtx = NULL;
955 ts = td_get_sched(td);
956 p = td->td_proc;
957
958 THREAD_LOCK_ASSERT(td, MA_OWNED);
959
960 /*
961 * Switch to the sched lock to fix things up and pick
962 * a new thread.
963 * Block the td_lock in order to avoid breaking the critical path.
964 */
965 if (td->td_lock != &sched_lock) {
966 mtx_lock_spin(&sched_lock);
967 tmtx = thread_lock_block(td);
968 }
969
970 if ((td->td_flags & TDF_NOLOAD) == 0)
971 sched_load_rem();
972
973 td->td_lastcpu = td->td_oncpu;
974 preempted = (td->td_flags & TDF_SLICEEND) == 0 &&
975 (flags & SW_PREEMPT) != 0;
976 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND);
977 td->td_owepreempt = 0;
978 td->td_oncpu = NOCPU;
979
980 /*
981 * At the last moment, if this thread is still marked RUNNING,
982 * then put it back on the run queue as it has not been suspended
983 * or stopped or any thing else similar. We never put the idle
984 * threads on the run queue, however.
985 */
986 if (td->td_flags & TDF_IDLETD) {
987 TD_SET_CAN_RUN(td);
988 #ifdef SMP
989 CPU_CLR(PCPU_GET(cpuid), &idle_cpus_mask);
990 #endif
991 } else {
992 if (TD_IS_RUNNING(td)) {
993 /* Put us back on the run queue. */
994 sched_add(td, preempted ?
995 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
996 SRQ_OURSELF|SRQ_YIELDING);
997 }
998 }
999 if (newtd) {
1000 /*
1001 * The thread we are about to run needs to be counted
1002 * as if it had been added to the run queue and selected.
1003 * It came from:
1004 * * A preemption
1005 * * An upcall
1006 * * A followon
1007 */
1008 KASSERT((newtd->td_inhibitors == 0),
1009 ("trying to run inhibited thread"));
1010 newtd->td_flags |= TDF_DIDRUN;
1011 TD_SET_RUNNING(newtd);
1012 if ((newtd->td_flags & TDF_NOLOAD) == 0)
1013 sched_load_add();
1014 } else {
1015 newtd = choosethread();
1016 MPASS(newtd->td_lock == &sched_lock);
1017 }
1018
1019 #if (KTR_COMPILE & KTR_SCHED) != 0
1020 if (TD_IS_IDLETHREAD(td))
1021 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle",
1022 "prio:%d", td->td_priority);
1023 else
1024 KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td),
1025 "prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg,
1026 "lockname:\"%s\"", td->td_lockname);
1027 #endif
1028
1029 if (td != newtd) {
1030 #ifdef HWPMC_HOOKS
1031 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1032 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
1033 #endif
1034
1035 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc);
1036
1037 /* I feel sleepy */
1038 lock_profile_release_lock(&sched_lock.lock_object);
1039 #ifdef KDTRACE_HOOKS
1040 /*
1041 * If DTrace has set the active vtime enum to anything
1042 * other than INACTIVE (0), then it should have set the
1043 * function to call.
1044 */
1045 if (dtrace_vtime_active)
1046 (*dtrace_vtime_switch_func)(newtd);
1047 #endif
1048
1049 cpu_switch(td, newtd, tmtx != NULL ? tmtx : td->td_lock);
1050 lock_profile_obtain_lock_success(&sched_lock.lock_object,
1051 0, 0, __FILE__, __LINE__);
1052 /*
1053 * Where am I? What year is it?
1054 * We are in the same thread that went to sleep above,
1055 * but any amount of time may have passed. All our context
1056 * will still be available as will local variables.
1057 * PCPU values however may have changed as we may have
1058 * changed CPU so don't trust cached values of them.
1059 * New threads will go to fork_exit() instead of here
1060 * so if you change things here you may need to change
1061 * things there too.
1062 *
1063 * If the thread above was exiting it will never wake
1064 * up again here, so either it has saved everything it
1065 * needed to, or the thread_wait() or wait() will
1066 * need to reap it.
1067 */
1068
1069 SDT_PROBE0(sched, , , on__cpu);
1070 #ifdef HWPMC_HOOKS
1071 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1072 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
1073 #endif
1074 } else
1075 SDT_PROBE0(sched, , , remain__cpu);
1076
1077 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running",
1078 "prio:%d", td->td_priority);
1079
1080 #ifdef SMP
1081 if (td->td_flags & TDF_IDLETD)
1082 CPU_SET(PCPU_GET(cpuid), &idle_cpus_mask);
1083 #endif
1084 sched_lock.mtx_lock = (uintptr_t)td;
1085 td->td_oncpu = PCPU_GET(cpuid);
1086 MPASS(td->td_lock == &sched_lock);
1087 }
1088
1089 void
1090 sched_wakeup(struct thread *td)
1091 {
1092 struct td_sched *ts;
1093
1094 THREAD_LOCK_ASSERT(td, MA_OWNED);
1095 ts = td_get_sched(td);
1096 td->td_flags &= ~TDF_CANSWAP;
1097 if (ts->ts_slptime > 1) {
1098 updatepri(td);
1099 resetpriority(td);
1100 }
1101 td->td_slptick = 0;
1102 ts->ts_slptime = 0;
1103 ts->ts_slice = sched_slice;
1104 sched_add(td, SRQ_BORING);
1105 }
1106
1107 #ifdef SMP
1108 static int
1109 forward_wakeup(int cpunum)
1110 {
1111 struct pcpu *pc;
1112 cpuset_t dontuse, map, map2;
1113 u_int id, me;
1114 int iscpuset;
1115
1116 mtx_assert(&sched_lock, MA_OWNED);
1117
1118 CTR0(KTR_RUNQ, "forward_wakeup()");
1119
1120 if ((!forward_wakeup_enabled) ||
1121 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0))
1122 return (0);
1123 if (!smp_started || panicstr)
1124 return (0);
1125
1126 forward_wakeups_requested++;
1127
1128 /*
1129 * Check the idle mask we received against what we calculated
1130 * before in the old version.
1131 */
1132 me = PCPU_GET(cpuid);
1133
1134 /* Don't bother if we should be doing it ourself. */
1135 if (CPU_ISSET(me, &idle_cpus_mask) &&
1136 (cpunum == NOCPU || me == cpunum))
1137 return (0);
1138
1139 CPU_SETOF(me, &dontuse);
1140 CPU_OR(&dontuse, &stopped_cpus);
1141 CPU_OR(&dontuse, &hlt_cpus_mask);
1142 CPU_ZERO(&map2);
1143 if (forward_wakeup_use_loop) {
1144 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
1145 id = pc->pc_cpuid;
1146 if (!CPU_ISSET(id, &dontuse) &&
1147 pc->pc_curthread == pc->pc_idlethread) {
1148 CPU_SET(id, &map2);
1149 }
1150 }
1151 }
1152
1153 if (forward_wakeup_use_mask) {
1154 map = idle_cpus_mask;
1155 CPU_NAND(&map, &dontuse);
1156
1157 /* If they are both on, compare and use loop if different. */
1158 if (forward_wakeup_use_loop) {
1159 if (CPU_CMP(&map, &map2)) {
1160 printf("map != map2, loop method preferred\n");
1161 map = map2;
1162 }
1163 }
1164 } else {
1165 map = map2;
1166 }
1167
1168 /* If we only allow a specific CPU, then mask off all the others. */
1169 if (cpunum != NOCPU) {
1170 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum."));
1171 iscpuset = CPU_ISSET(cpunum, &map);
1172 if (iscpuset == 0)
1173 CPU_ZERO(&map);
1174 else
1175 CPU_SETOF(cpunum, &map);
1176 }
1177 if (!CPU_EMPTY(&map)) {
1178 forward_wakeups_delivered++;
1179 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
1180 id = pc->pc_cpuid;
1181 if (!CPU_ISSET(id, &map))
1182 continue;
1183 if (cpu_idle_wakeup(pc->pc_cpuid))
1184 CPU_CLR(id, &map);
1185 }
1186 if (!CPU_EMPTY(&map))
1187 ipi_selected(map, IPI_AST);
1188 return (1);
1189 }
1190 if (cpunum == NOCPU)
1191 printf("forward_wakeup: Idle processor not found\n");
1192 return (0);
1193 }
1194
1195 static void
1196 kick_other_cpu(int pri, int cpuid)
1197 {
1198 struct pcpu *pcpu;
1199 int cpri;
1200
1201 pcpu = pcpu_find(cpuid);
1202 if (CPU_ISSET(cpuid, &idle_cpus_mask)) {
1203 forward_wakeups_delivered++;
1204 if (!cpu_idle_wakeup(cpuid))
1205 ipi_cpu(cpuid, IPI_AST);
1206 return;
1207 }
1208
1209 cpri = pcpu->pc_curthread->td_priority;
1210 if (pri >= cpri)
1211 return;
1212
1213 #if defined(IPI_PREEMPTION) && defined(PREEMPTION)
1214 #if !defined(FULL_PREEMPTION)
1215 if (pri <= PRI_MAX_ITHD)
1216 #endif /* ! FULL_PREEMPTION */
1217 {
1218 ipi_cpu(cpuid, IPI_PREEMPT);
1219 return;
1220 }
1221 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */
1222
1223 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED;
1224 ipi_cpu(cpuid, IPI_AST);
1225 return;
1226 }
1227 #endif /* SMP */
1228
1229 #ifdef SMP
1230 static int
1231 sched_pickcpu(struct thread *td)
1232 {
1233 int best, cpu;
1234
1235 mtx_assert(&sched_lock, MA_OWNED);
1236
1237 if (td->td_lastcpu != NOCPU && THREAD_CAN_SCHED(td, td->td_lastcpu))
1238 best = td->td_lastcpu;
1239 else
1240 best = NOCPU;
1241 CPU_FOREACH(cpu) {
1242 if (!THREAD_CAN_SCHED(td, cpu))
1243 continue;
1244
1245 if (best == NOCPU)
1246 best = cpu;
1247 else if (runq_length[cpu] < runq_length[best])
1248 best = cpu;
1249 }
1250 KASSERT(best != NOCPU, ("no valid CPUs"));
1251
1252 return (best);
1253 }
1254 #endif
1255
1256 void
1257 sched_add(struct thread *td, int flags)
1258 #ifdef SMP
1259 {
1260 cpuset_t tidlemsk;
1261 struct td_sched *ts;
1262 u_int cpu, cpuid;
1263 int forwarded = 0;
1264 int single_cpu = 0;
1265
1266 ts = td_get_sched(td);
1267 THREAD_LOCK_ASSERT(td, MA_OWNED);
1268 KASSERT((td->td_inhibitors == 0),
1269 ("sched_add: trying to run inhibited thread"));
1270 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
1271 ("sched_add: bad thread state"));
1272 KASSERT(td->td_flags & TDF_INMEM,
1273 ("sched_add: thread swapped out"));
1274
1275 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
1276 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
1277 sched_tdname(curthread));
1278 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
1279 KTR_ATTR_LINKED, sched_tdname(td));
1280 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL,
1281 flags & SRQ_PREEMPTED);
1282
1283
1284 /*
1285 * Now that the thread is moving to the run-queue, set the lock
1286 * to the scheduler's lock.
1287 */
1288 if (td->td_lock != &sched_lock) {
1289 mtx_lock_spin(&sched_lock);
1290 thread_lock_set(td, &sched_lock);
1291 }
1292 TD_SET_RUNQ(td);
1293
1294 /*
1295 * If SMP is started and the thread is pinned or otherwise limited to
1296 * a specific set of CPUs, queue the thread to a per-CPU run queue.
1297 * Otherwise, queue the thread to the global run queue.
1298 *
1299 * If SMP has not yet been started we must use the global run queue
1300 * as per-CPU state may not be initialized yet and we may crash if we
1301 * try to access the per-CPU run queues.
1302 */
1303 if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND ||
1304 ts->ts_flags & TSF_AFFINITY)) {
1305 if (td->td_pinned != 0)
1306 cpu = td->td_lastcpu;
1307 else if (td->td_flags & TDF_BOUND) {
1308 /* Find CPU from bound runq. */
1309 KASSERT(SKE_RUNQ_PCPU(ts),
1310 ("sched_add: bound td_sched not on cpu runq"));
1311 cpu = ts->ts_runq - &runq_pcpu[0];
1312 } else
1313 /* Find a valid CPU for our cpuset */
1314 cpu = sched_pickcpu(td);
1315 ts->ts_runq = &runq_pcpu[cpu];
1316 single_cpu = 1;
1317 CTR3(KTR_RUNQ,
1318 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td,
1319 cpu);
1320 } else {
1321 CTR2(KTR_RUNQ,
1322 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts,
1323 td);
1324 cpu = NOCPU;
1325 ts->ts_runq = &runq;
1326 }
1327
1328 if ((td->td_flags & TDF_NOLOAD) == 0)
1329 sched_load_add();
1330 runq_add(ts->ts_runq, td, flags);
1331 if (cpu != NOCPU)
1332 runq_length[cpu]++;
1333
1334 cpuid = PCPU_GET(cpuid);
1335 if (single_cpu && cpu != cpuid) {
1336 kick_other_cpu(td->td_priority, cpu);
1337 } else {
1338 if (!single_cpu) {
1339 tidlemsk = idle_cpus_mask;
1340 CPU_NAND(&tidlemsk, &hlt_cpus_mask);
1341 CPU_CLR(cpuid, &tidlemsk);
1342
1343 if (!CPU_ISSET(cpuid, &idle_cpus_mask) &&
1344 ((flags & SRQ_INTR) == 0) &&
1345 !CPU_EMPTY(&tidlemsk))
1346 forwarded = forward_wakeup(cpu);
1347 }
1348
1349 if (!forwarded) {
1350 if (!maybe_preempt(td))
1351 maybe_resched(td);
1352 }
1353 }
1354 }
1355 #else /* SMP */
1356 {
1357 struct td_sched *ts;
1358
1359 ts = td_get_sched(td);
1360 THREAD_LOCK_ASSERT(td, MA_OWNED);
1361 KASSERT((td->td_inhibitors == 0),
1362 ("sched_add: trying to run inhibited thread"));
1363 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
1364 ("sched_add: bad thread state"));
1365 KASSERT(td->td_flags & TDF_INMEM,
1366 ("sched_add: thread swapped out"));
1367 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
1368 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
1369 sched_tdname(curthread));
1370 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
1371 KTR_ATTR_LINKED, sched_tdname(td));
1372 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL,
1373 flags & SRQ_PREEMPTED);
1374
1375 /*
1376 * Now that the thread is moving to the run-queue, set the lock
1377 * to the scheduler's lock.
1378 */
1379 if (td->td_lock != &sched_lock) {
1380 mtx_lock_spin(&sched_lock);
1381 thread_lock_set(td, &sched_lock);
1382 }
1383 TD_SET_RUNQ(td);
1384 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td);
1385 ts->ts_runq = &runq;
1386
1387 if ((td->td_flags & TDF_NOLOAD) == 0)
1388 sched_load_add();
1389 runq_add(ts->ts_runq, td, flags);
1390 if (!maybe_preempt(td))
1391 maybe_resched(td);
1392 }
1393 #endif /* SMP */
1394
1395 void
1396 sched_rem(struct thread *td)
1397 {
1398 struct td_sched *ts;
1399
1400 ts = td_get_sched(td);
1401 KASSERT(td->td_flags & TDF_INMEM,
1402 ("sched_rem: thread swapped out"));
1403 KASSERT(TD_ON_RUNQ(td),
1404 ("sched_rem: thread not on run queue"));
1405 mtx_assert(&sched_lock, MA_OWNED);
1406 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem",
1407 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
1408 sched_tdname(curthread));
1409 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL);
1410
1411 if ((td->td_flags & TDF_NOLOAD) == 0)
1412 sched_load_rem();
1413 #ifdef SMP
1414 if (ts->ts_runq != &runq)
1415 runq_length[ts->ts_runq - runq_pcpu]--;
1416 #endif
1417 runq_remove(ts->ts_runq, td);
1418 TD_SET_CAN_RUN(td);
1419 }
1420
1421 /*
1422 * Select threads to run. Note that running threads still consume a
1423 * slot.
1424 */
1425 struct thread *
1426 sched_choose(void)
1427 {
1428 struct thread *td;
1429 struct runq *rq;
1430
1431 mtx_assert(&sched_lock, MA_OWNED);
1432 #ifdef SMP
1433 struct thread *tdcpu;
1434
1435 rq = &runq;
1436 td = runq_choose_fuzz(&runq, runq_fuzz);
1437 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]);
1438
1439 if (td == NULL ||
1440 (tdcpu != NULL &&
1441 tdcpu->td_priority < td->td_priority)) {
1442 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu,
1443 PCPU_GET(cpuid));
1444 td = tdcpu;
1445 rq = &runq_pcpu[PCPU_GET(cpuid)];
1446 } else {
1447 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td);
1448 }
1449
1450 #else
1451 rq = &runq;
1452 td = runq_choose(&runq);
1453 #endif
1454
1455 if (td) {
1456 #ifdef SMP
1457 if (td == tdcpu)
1458 runq_length[PCPU_GET(cpuid)]--;
1459 #endif
1460 runq_remove(rq, td);
1461 td->td_flags |= TDF_DIDRUN;
1462
1463 KASSERT(td->td_flags & TDF_INMEM,
1464 ("sched_choose: thread swapped out"));
1465 return (td);
1466 }
1467 return (PCPU_GET(idlethread));
1468 }
1469
1470 void
1471 sched_preempt(struct thread *td)
1472 {
1473
1474 SDT_PROBE2(sched, , , surrender, td, td->td_proc);
1475 thread_lock(td);
1476 if (td->td_critnest > 1)
1477 td->td_owepreempt = 1;
1478 else
1479 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, NULL);
1480 thread_unlock(td);
1481 }
1482
1483 void
1484 sched_userret_slowpath(struct thread *td)
1485 {
1486
1487 thread_lock(td);
1488 td->td_priority = td->td_user_pri;
1489 td->td_base_pri = td->td_user_pri;
1490 thread_unlock(td);
1491 }
1492
1493 void
1494 sched_bind(struct thread *td, int cpu)
1495 {
1496 struct td_sched *ts;
1497
1498 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED);
1499 KASSERT(td == curthread, ("sched_bind: can only bind curthread"));
1500
1501 ts = td_get_sched(td);
1502
1503 td->td_flags |= TDF_BOUND;
1504 #ifdef SMP
1505 ts->ts_runq = &runq_pcpu[cpu];
1506 if (PCPU_GET(cpuid) == cpu)
1507 return;
1508
1509 mi_switch(SW_VOL, NULL);
1510 #endif
1511 }
1512
1513 void
1514 sched_unbind(struct thread* td)
1515 {
1516 THREAD_LOCK_ASSERT(td, MA_OWNED);
1517 KASSERT(td == curthread, ("sched_unbind: can only bind curthread"));
1518 td->td_flags &= ~TDF_BOUND;
1519 }
1520
1521 int
1522 sched_is_bound(struct thread *td)
1523 {
1524 THREAD_LOCK_ASSERT(td, MA_OWNED);
1525 return (td->td_flags & TDF_BOUND);
1526 }
1527
1528 void
1529 sched_relinquish(struct thread *td)
1530 {
1531 thread_lock(td);
1532 mi_switch(SW_VOL | SWT_RELINQUISH, NULL);
1533 thread_unlock(td);
1534 }
1535
1536 int
1537 sched_load(void)
1538 {
1539 return (sched_tdcnt);
1540 }
1541
1542 int
1543 sched_sizeof_proc(void)
1544 {
1545 return (sizeof(struct proc));
1546 }
1547
1548 int
1549 sched_sizeof_thread(void)
1550 {
1551 return (sizeof(struct thread) + sizeof(struct td_sched));
1552 }
1553
1554 fixpt_t
1555 sched_pctcpu(struct thread *td)
1556 {
1557 struct td_sched *ts;
1558
1559 THREAD_LOCK_ASSERT(td, MA_OWNED);
1560 ts = td_get_sched(td);
1561 return (ts->ts_pctcpu);
1562 }
1563
1564 #ifdef RACCT
1565 /*
1566 * Calculates the contribution to the thread cpu usage for the latest
1567 * (unfinished) second.
1568 */
1569 fixpt_t
1570 sched_pctcpu_delta(struct thread *td)
1571 {
1572 struct td_sched *ts;
1573 fixpt_t delta;
1574 int realstathz;
1575
1576 THREAD_LOCK_ASSERT(td, MA_OWNED);
1577 ts = td_get_sched(td);
1578 delta = 0;
1579 realstathz = stathz ? stathz : hz;
1580 if (ts->ts_cpticks != 0) {
1581 #if (FSHIFT >= CCPU_SHIFT)
1582 delta = (realstathz == 100)
1583 ? ((fixpt_t) ts->ts_cpticks) <<
1584 (FSHIFT - CCPU_SHIFT) :
1585 100 * (((fixpt_t) ts->ts_cpticks)
1586 << (FSHIFT - CCPU_SHIFT)) / realstathz;
1587 #else
1588 delta = ((FSCALE - ccpu) *
1589 (ts->ts_cpticks *
1590 FSCALE / realstathz)) >> FSHIFT;
1591 #endif
1592 }
1593
1594 return (delta);
1595 }
1596 #endif
1597
1598 u_int
1599 sched_estcpu(struct thread *td)
1600 {
1601
1602 return (td_get_sched(td)->ts_estcpu);
1603 }
1604
1605 /*
1606 * The actual idle process.
1607 */
1608 void
1609 sched_idletd(void *dummy)
1610 {
1611 struct pcpuidlestat *stat;
1612
1613 THREAD_NO_SLEEPING();
1614 stat = DPCPU_PTR(idlestat);
1615 for (;;) {
1616 mtx_assert(&Giant, MA_NOTOWNED);
1617
1618 while (sched_runnable() == 0) {
1619 cpu_idle(stat->idlecalls + stat->oldidlecalls > 64);
1620 stat->idlecalls++;
1621 }
1622
1623 mtx_lock_spin(&sched_lock);
1624 mi_switch(SW_VOL | SWT_IDLE, NULL);
1625 mtx_unlock_spin(&sched_lock);
1626 }
1627 }
1628
1629 /*
1630 * A CPU is entering for the first time or a thread is exiting.
1631 */
1632 void
1633 sched_throw(struct thread *td)
1634 {
1635 /*
1636 * Correct spinlock nesting. The idle thread context that we are
1637 * borrowing was created so that it would start out with a single
1638 * spin lock (sched_lock) held in fork_trampoline(). Since we've
1639 * explicitly acquired locks in this function, the nesting count
1640 * is now 2 rather than 1. Since we are nested, calling
1641 * spinlock_exit() will simply adjust the counts without allowing
1642 * spin lock using code to interrupt us.
1643 */
1644 if (td == NULL) {
1645 mtx_lock_spin(&sched_lock);
1646 spinlock_exit();
1647 PCPU_SET(switchtime, cpu_ticks());
1648 PCPU_SET(switchticks, ticks);
1649 } else {
1650 lock_profile_release_lock(&sched_lock.lock_object);
1651 MPASS(td->td_lock == &sched_lock);
1652 td->td_lastcpu = td->td_oncpu;
1653 td->td_oncpu = NOCPU;
1654 }
1655 mtx_assert(&sched_lock, MA_OWNED);
1656 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count"));
1657 cpu_throw(td, choosethread()); /* doesn't return */
1658 }
1659
1660 void
1661 sched_fork_exit(struct thread *td)
1662 {
1663
1664 /*
1665 * Finish setting up thread glue so that it begins execution in a
1666 * non-nested critical section with sched_lock held but not recursed.
1667 */
1668 td->td_oncpu = PCPU_GET(cpuid);
1669 sched_lock.mtx_lock = (uintptr_t)td;
1670 lock_profile_obtain_lock_success(&sched_lock.lock_object,
1671 0, 0, __FILE__, __LINE__);
1672 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED);
1673
1674 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running",
1675 "prio:%d", td->td_priority);
1676 SDT_PROBE0(sched, , , on__cpu);
1677 }
1678
1679 char *
1680 sched_tdname(struct thread *td)
1681 {
1682 #ifdef KTR
1683 struct td_sched *ts;
1684
1685 ts = td_get_sched(td);
1686 if (ts->ts_name[0] == '\0')
1687 snprintf(ts->ts_name, sizeof(ts->ts_name),
1688 "%s tid %d", td->td_name, td->td_tid);
1689 return (ts->ts_name);
1690 #else
1691 return (td->td_name);
1692 #endif
1693 }
1694
1695 #ifdef KTR
1696 void
1697 sched_clear_tdname(struct thread *td)
1698 {
1699 struct td_sched *ts;
1700
1701 ts = td_get_sched(td);
1702 ts->ts_name[0] = '\0';
1703 }
1704 #endif
1705
1706 void
1707 sched_affinity(struct thread *td)
1708 {
1709 #ifdef SMP
1710 struct td_sched *ts;
1711 int cpu;
1712
1713 THREAD_LOCK_ASSERT(td, MA_OWNED);
1714
1715 /*
1716 * Set the TSF_AFFINITY flag if there is at least one CPU this
1717 * thread can't run on.
1718 */
1719 ts = td_get_sched(td);
1720 ts->ts_flags &= ~TSF_AFFINITY;
1721 CPU_FOREACH(cpu) {
1722 if (!THREAD_CAN_SCHED(td, cpu)) {
1723 ts->ts_flags |= TSF_AFFINITY;
1724 break;
1725 }
1726 }
1727
1728 /*
1729 * If this thread can run on all CPUs, nothing else to do.
1730 */
1731 if (!(ts->ts_flags & TSF_AFFINITY))
1732 return;
1733
1734 /* Pinned threads and bound threads should be left alone. */
1735 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND)
1736 return;
1737
1738 switch (td->td_state) {
1739 case TDS_RUNQ:
1740 /*
1741 * If we are on a per-CPU runqueue that is in the set,
1742 * then nothing needs to be done.
1743 */
1744 if (ts->ts_runq != &runq &&
1745 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu))
1746 return;
1747
1748 /* Put this thread on a valid per-CPU runqueue. */
1749 sched_rem(td);
1750 sched_add(td, SRQ_BORING);
1751 break;
1752 case TDS_RUNNING:
1753 /*
1754 * See if our current CPU is in the set. If not, force a
1755 * context switch.
1756 */
1757 if (THREAD_CAN_SCHED(td, td->td_oncpu))
1758 return;
1759
1760 td->td_flags |= TDF_NEEDRESCHED;
1761 if (td != curthread)
1762 ipi_cpu(cpu, IPI_AST);
1763 break;
1764 default:
1765 break;
1766 }
1767 #endif
1768 }
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