Style(9) cleanup.
[dragonfly.git] / sys / kern / kern_synch.c
CommitLineData
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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 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the University of
21 * California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * @(#)kern_synch.c 8.9 (Berkeley) 5/19/95
39 * $FreeBSD: src/sys/kern/kern_synch.c,v 1.87.2.6 2002/10/13 07:29:53 kbyanc Exp $
6656cd91 40 * $DragonFly: src/sys/kern/kern_synch.c,v 1.29 2004/03/08 03:05:27 dillon Exp $
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41 */
42
43#include "opt_ktrace.h"
44
45#include <sys/param.h>
46#include <sys/systm.h>
47#include <sys/proc.h>
48#include <sys/kernel.h>
49#include <sys/signalvar.h>
50#include <sys/resourcevar.h>
51#include <sys/vmmeter.h>
52#include <sys/sysctl.h>
26a0694b 53#include <sys/thread2.h>
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54#ifdef KTRACE
55#include <sys/uio.h>
56#include <sys/ktrace.h>
57#endif
f1d1c3fa 58#include <sys/xwait.h>
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59
60#include <machine/cpu.h>
61#include <machine/ipl.h>
62#include <machine/smp.h>
63
402ed7e1 64static void sched_setup (void *dummy);
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65SYSINIT(sched_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, sched_setup, NULL)
66
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67int hogticks;
68int lbolt;
69int sched_quantum; /* Roundrobin scheduling quantum in ticks. */
17a9f566 70int ncpus;
90100055 71int ncpus2, ncpus2_shift, ncpus2_mask;
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72
73static struct callout loadav_callout;
74
75struct loadavg averunnable =
76 { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */
77/*
78 * Constants for averages over 1, 5, and 15 minutes
79 * when sampling at 5 second intervals.
80 */
81static fixpt_t cexp[3] = {
82 0.9200444146293232 * FSCALE, /* exp(-1/12) */
83 0.9834714538216174 * FSCALE, /* exp(-1/60) */
84 0.9944598480048967 * FSCALE, /* exp(-1/180) */
85};
86
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87static void endtsleep (void *);
88static void loadav (void *arg);
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89static void roundrobin (void *arg);
90static void schedcpu (void *arg);
91static void updatepri (struct proc *p);
8a8d5d85 92static void crit_panicints(void);
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93
94static int
95sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
96{
97 int error, new_val;
98
99 new_val = sched_quantum * tick;
100 error = sysctl_handle_int(oidp, &new_val, 0, req);
101 if (error != 0 || req->newptr == NULL)
102 return (error);
103 if (new_val < tick)
104 return (EINVAL);
105 sched_quantum = new_val / tick;
106 hogticks = 2 * sched_quantum;
107 return (0);
108}
109
110SYSCTL_PROC(_kern, OID_AUTO, quantum, CTLTYPE_INT|CTLFLAG_RW,
111 0, sizeof sched_quantum, sysctl_kern_quantum, "I", "");
112
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113int
114roundrobin_interval(void)
115{
116 return (sched_quantum);
117}
118
119/*
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120 * Force switch among equal priority processes every 100ms.
121 *
122 * WARNING! The MP lock is not held on ipi message remotes.
984263bc 123 */
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124#ifdef SMP
125
984263bc 126static void
cb973d15 127roundrobin_remote(void *arg)
984263bc 128{
8a8d5d85 129 struct proc *p = lwkt_preempted_proc();
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130 if (p == NULL || RTP_PRIO_NEED_RR(p->p_rtprio.type))
131 need_resched();
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132}
133
134#endif
135
136static void
137roundrobin(void *arg)
138{
139 struct proc *p = lwkt_preempted_proc();
8a8d5d85 140 if (p == NULL || RTP_PRIO_NEED_RR(p->p_rtprio.type))
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141 need_resched();
142#ifdef SMP
143 lwkt_send_ipiq_mask(mycpu->gd_other_cpus, roundrobin_remote, NULL);
984263bc 144#endif
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145 timeout(roundrobin, NULL, sched_quantum);
146}
147
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148#ifdef SMP
149
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150void
151resched_cpus(u_int32_t mask)
152{
153 lwkt_send_ipiq_mask(mask, roundrobin_remote, NULL);
154}
155
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156#endif
157
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158/*
159 * Constants for digital decay and forget:
160 * 90% of (p_estcpu) usage in 5 * loadav time
161 * 95% of (p_pctcpu) usage in 60 seconds (load insensitive)
162 * Note that, as ps(1) mentions, this can let percentages
163 * total over 100% (I've seen 137.9% for 3 processes).
164 *
88c4d2f6 165 * Note that schedulerclock() updates p_estcpu and p_cpticks asynchronously.
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166 *
167 * We wish to decay away 90% of p_estcpu in (5 * loadavg) seconds.
168 * That is, the system wants to compute a value of decay such
169 * that the following for loop:
170 * for (i = 0; i < (5 * loadavg); i++)
171 * p_estcpu *= decay;
172 * will compute
173 * p_estcpu *= 0.1;
174 * for all values of loadavg:
175 *
176 * Mathematically this loop can be expressed by saying:
177 * decay ** (5 * loadavg) ~= .1
178 *
179 * The system computes decay as:
180 * decay = (2 * loadavg) / (2 * loadavg + 1)
181 *
182 * We wish to prove that the system's computation of decay
183 * will always fulfill the equation:
184 * decay ** (5 * loadavg) ~= .1
185 *
186 * If we compute b as:
187 * b = 2 * loadavg
188 * then
189 * decay = b / (b + 1)
190 *
191 * We now need to prove two things:
192 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1)
193 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg)
194 *
195 * Facts:
196 * For x close to zero, exp(x) =~ 1 + x, since
197 * exp(x) = 0! + x**1/1! + x**2/2! + ... .
198 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b.
199 * For x close to zero, ln(1+x) =~ x, since
200 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1
201 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1).
202 * ln(.1) =~ -2.30
203 *
204 * Proof of (1):
205 * Solve (factor)**(power) =~ .1 given power (5*loadav):
206 * solving for factor,
207 * ln(factor) =~ (-2.30/5*loadav), or
208 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) =
209 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED
210 *
211 * Proof of (2):
212 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)):
213 * solving for power,
214 * power*ln(b/(b+1)) =~ -2.30, or
215 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED
216 *
217 * Actual power values for the implemented algorithm are as follows:
218 * loadav: 1 2 3 4
219 * power: 5.68 10.32 14.94 19.55
220 */
221
222/* calculations for digital decay to forget 90% of usage in 5*loadav sec */
223#define loadfactor(loadav) (2 * (loadav))
224#define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE))
225
226/* decay 95% of `p_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */
227static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
228SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");
229
230/* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */
231static int fscale __unused = FSCALE;
232SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, "");
233
234/*
235 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the
236 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below
237 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT).
238 *
239 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used:
240 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits).
241 *
242 * If you don't want to bother with the faster/more-accurate formula, you
243 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate
244 * (more general) method of calculating the %age of CPU used by a process.
245 */
246#define CCPU_SHIFT 11
247
248/*
249 * Recompute process priorities, every hz ticks.
250 */
251/* ARGSUSED */
252static void
26a0694b 253schedcpu(void *arg)
984263bc 254{
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255 fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
256 struct proc *p;
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257 int realstathz, s;
258
984263bc 259 realstathz = stathz ? stathz : hz;
f62004ad 260 FOREACH_PROC_IN_SYSTEM(p) {
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261 /*
262 * Increment time in/out of memory and sleep time
263 * (if sleeping). We ignore overflow; with 16-bit int's
264 * (remember them?) overflow takes 45 days.
265 */
266 p->p_swtime++;
267 if (p->p_stat == SSLEEP || p->p_stat == SSTOP)
268 p->p_slptime++;
269 p->p_pctcpu = (p->p_pctcpu * ccpu) >> FSHIFT;
270 /*
271 * If the process has slept the entire second,
272 * stop recalculating its priority until it wakes up.
273 */
274 if (p->p_slptime > 1)
275 continue;
276 s = splhigh(); /* prevent state changes and protect run queue */
277 /*
278 * p_pctcpu is only for ps.
279 */
280#if (FSHIFT >= CCPU_SHIFT)
281 p->p_pctcpu += (realstathz == 100)?
282 ((fixpt_t) p->p_cpticks) << (FSHIFT - CCPU_SHIFT):
283 100 * (((fixpt_t) p->p_cpticks)
284 << (FSHIFT - CCPU_SHIFT)) / realstathz;
285#else
286 p->p_pctcpu += ((FSCALE - ccpu) *
287 (p->p_cpticks * FSCALE / realstathz)) >> FSHIFT;
288#endif
289 p->p_cpticks = 0;
290 p->p_estcpu = decay_cpu(loadfac, p->p_estcpu);
291 resetpriority(p);
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292 splx(s);
293 }
294 wakeup((caddr_t)&lbolt);
295 timeout(schedcpu, (void *)0, hz);
296}
297
298/*
299 * Recalculate the priority of a process after it has slept for a while.
300 * For all load averages >= 1 and max p_estcpu of 255, sleeping for at
301 * least six times the loadfactor will decay p_estcpu to zero.
302 */
303static void
26a0694b 304updatepri(struct proc *p)
984263bc 305{
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306 unsigned int newcpu = p->p_estcpu;
307 fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
984263bc 308
26a0694b 309 if (p->p_slptime > 5 * loadfac) {
984263bc 310 p->p_estcpu = 0;
26a0694b 311 } else {
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312 p->p_slptime--; /* the first time was done in schedcpu */
313 while (newcpu && --p->p_slptime)
314 newcpu = decay_cpu(loadfac, newcpu);
315 p->p_estcpu = newcpu;
316 }
317 resetpriority(p);
318}
319
320/*
321 * We're only looking at 7 bits of the address; everything is
322 * aligned to 4, lots of things are aligned to greater powers
323 * of 2. Shift right by 8, i.e. drop the bottom 256 worth.
324 */
325#define TABLESIZE 128
0cfcada1 326static TAILQ_HEAD(slpquehead, thread) slpque[TABLESIZE];
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327#define LOOKUP(x) (((intptr_t)(x) >> 8) & (TABLESIZE - 1))
328
329/*
330 * During autoconfiguration or after a panic, a sleep will simply
331 * lower the priority briefly to allow interrupts, then return.
332 * The priority to be used (safepri) is machine-dependent, thus this
333 * value is initialized and maintained in the machine-dependent layers.
334 * This priority will typically be 0, or the lowest priority
335 * that is safe for use on the interrupt stack; it can be made
336 * higher to block network software interrupts after panics.
337 */
338int safepri;
339
340void
341sleepinit(void)
342{
343 int i;
344
345 sched_quantum = hz/10;
346 hogticks = 2 * sched_quantum;
347 for (i = 0; i < TABLESIZE; i++)
348 TAILQ_INIT(&slpque[i]);
349}
350
351/*
352 * General sleep call. Suspends the current process until a wakeup is
353 * performed on the specified identifier. The process will then be made
354 * runnable with the specified priority. Sleeps at most timo/hz seconds
377d4740 355 * (0 means no timeout). If flags includes PCATCH flag, signals are checked
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356 * before and after sleeping, else signals are not checked. Returns 0 if
357 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a
358 * signal needs to be delivered, ERESTART is returned if the current system
359 * call should be restarted if possible, and EINTR is returned if the system
360 * call should be interrupted by the signal (return EINTR).
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361 *
362 * If the process has P_CURPROC set mi_switch() will not re-queue it to
363 * the userland scheduler queues because we are in a SSLEEP state. If
364 * we are not the current process then we have to remove ourselves from
365 * the scheduler queues.
366 *
367 * YYY priority now unused
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368 */
369int
6656cd91 370tsleep(void *ident, int flags, const char *wmesg, int timo)
984263bc 371{
dadab5e9 372 struct thread *td = curthread;
0cfcada1 373 struct proc *p = td->td_proc; /* may be NULL */
377d4740 374 int s, sig = 0, catch = flags & PCATCH;
f1d1c3fa 375 int id = LOOKUP(ident);
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376 struct callout_handle thandle;
377
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378 /*
379 * NOTE: removed KTRPOINT, it could cause races due to blocking
380 * even in stable. Just scrap it for now.
381 */
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382 if (cold || panicstr) {
383 /*
384 * After a panic, or during autoconfiguration,
385 * just give interrupts a chance, then just return;
386 * don't run any other procs or panic below,
387 * in case this is the idle process and already asleep.
388 */
8a8d5d85 389 crit_panicints();
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390 return (0);
391 }
a2a5ad0d 392 KKASSERT(td != &mycpu->gd_idlethread); /* you must be kidding! */
8a8d5d85 393 s = splhigh();
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394 KASSERT(ident != NULL, ("tsleep: no ident"));
395 KASSERT(p == NULL || p->p_stat == SRUN, ("tsleep %p %s %d",
396 ident, wmesg, p->p_stat));
397
26a0694b 398 crit_enter();
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399 td->td_wchan = ident;
400 td->td_wmesg = wmesg;
26a0694b 401 if (p)
0cfcada1 402 p->p_slptime = 0;
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403 lwkt_deschedule_self();
404 TAILQ_INSERT_TAIL(&slpque[id], td, td_threadq);
984263bc 405 if (timo)
0cfcada1 406 thandle = timeout(endtsleep, (void *)td, timo);
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407 /*
408 * We put ourselves on the sleep queue and start our timeout
409 * before calling CURSIG, as we could stop there, and a wakeup
410 * or a SIGCONT (or both) could occur while we were stopped.
411 * A SIGCONT would cause us to be marked as SSLEEP
412 * without resuming us, thus we must be ready for sleep
413 * when CURSIG is called. If the wakeup happens while we're
a2a5ad0d 414 * stopped, td->td_wchan will be 0 upon return from CURSIG.
984263bc 415 */
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416 if (p) {
417 if (catch) {
418 p->p_flag |= P_SINTR;
419 if ((sig = CURSIG(p))) {
26a0694b 420 if (td->td_wchan) {
0cfcada1 421 unsleep(td);
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422 lwkt_schedule_self();
423 }
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424 p->p_stat = SRUN;
425 goto resume;
426 }
a2a5ad0d 427 if (td->td_wchan == NULL) {
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428 catch = 0;
429 goto resume;
430 }
431 } else {
432 sig = 0;
984263bc 433 }
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434
435 /*
436 * If we are not the current process we have to remove ourself
437 * from the run queue.
438 */
439 KASSERT(p->p_stat == SRUN, ("PSTAT NOT SRUN %d %d", p->p_pid, p->p_stat));
440 /*
441 * If this is the current 'user' process schedule another one.
442 */
443 clrrunnable(p, SSLEEP);
0cfcada1 444 p->p_stats->p_ru.ru_nvcsw++;
a2a5ad0d 445 KKASSERT(td->td_release || (p->p_flag & P_CURPROC) == 0);
0cfcada1 446 mi_switch();
26a0694b 447 KASSERT(p->p_stat == SRUN, ("tsleep: stat not srun"));
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448 } else {
449 lwkt_switch();
450 }
984263bc 451resume:
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452 crit_exit();
453 if (p)
0cfcada1 454 p->p_flag &= ~P_SINTR;
984263bc 455 splx(s);
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456 if (td->td_flags & TDF_TIMEOUT) {
457 td->td_flags &= ~TDF_TIMEOUT;
458 if (sig == 0)
984263bc 459 return (EWOULDBLOCK);
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460 } else if (timo) {
461 untimeout(endtsleep, (void *)td, thandle);
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462 } else if (td->td_wmesg) {
463 /*
464 * This can happen if a thread is woken up directly. Clear
465 * wmesg to avoid debugging confusion.
466 */
467 td->td_wmesg = NULL;
0cfcada1 468 }
a94976ad 469 /* inline of iscaught() */
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470 if (p) {
471 if (catch && (sig != 0 || (sig = CURSIG(p)))) {
472 if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig))
473 return (EINTR);
474 return (ERESTART);
984263bc 475 }
984263bc 476 }
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477 return (0);
478}
479
984263bc 480/*
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481 * Implement the timeout for tsleep. We interlock against
482 * wchan when setting TDF_TIMEOUT. For processes we remove
483 * the sleep if the process is stopped rather then sleeping,
484 * so it remains stopped.
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485 */
486static void
0cfcada1 487endtsleep(void *arg)
984263bc 488{
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489 thread_t td = arg;
490 struct proc *p;
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491 int s;
492
984263bc 493 s = splhigh();
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494 if (td->td_wchan) {
495 td->td_flags |= TDF_TIMEOUT;
496 if ((p = td->td_proc) != NULL) {
497 if (p->p_stat == SSLEEP)
498 setrunnable(p);
499 else
500 unsleep(td);
501 } else {
502 unsleep(td);
503 lwkt_schedule(td);
504 }
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505 }
506 splx(s);
507}
508
509/*
510 * Remove a process from its wait queue
511 */
512void
0cfcada1 513unsleep(struct thread *td)
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514{
515 int s;
516
517 s = splhigh();
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518 if (td->td_wchan) {
519#if 0
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520 if (p->p_flag & P_XSLEEP) {
521 struct xwait *w = p->p_wchan;
522 TAILQ_REMOVE(&w->waitq, p, p_procq);
523 p->p_flag &= ~P_XSLEEP;
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524 } else
525#endif
526 TAILQ_REMOVE(&slpque[LOOKUP(td->td_wchan)], td, td_threadq);
527 td->td_wchan = NULL;
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528 }
529 splx(s);
530}
531
0cfcada1 532#if 0
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533/*
534 * Make all processes sleeping on the explicit lock structure runnable.
535 */
536void
537xwakeup(struct xwait *w)
538{
539 struct proc *p;
540 int s;
541
542 s = splhigh();
543 ++w->gen;
544 while ((p = TAILQ_FIRST(&w->waitq)) != NULL) {
545 TAILQ_REMOVE(&w->waitq, p, p_procq);
546 KASSERT(p->p_wchan == w && (p->p_flag & P_XSLEEP),
547 ("xwakeup: wchan mismatch for %p (%p/%p) %08x", p, p->p_wchan, w, p->p_flag & P_XSLEEP));
548 p->p_wchan = NULL;
549 p->p_flag &= ~P_XSLEEP;
550 if (p->p_stat == SSLEEP) {
551 /* OPTIMIZED EXPANSION OF setrunnable(p); */
552 if (p->p_slptime > 1)
553 updatepri(p);
554 p->p_slptime = 0;
555 p->p_stat = SRUN;
556 if (p->p_flag & P_INMEM) {
557 setrunqueue(p);
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558 } else {
559 p->p_flag |= P_SWAPINREQ;
560 wakeup((caddr_t)&proc0);
561 }
562 }
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563 }
564 splx(s);
565}
0cfcada1 566#endif
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567
568/*
569 * Make all processes sleeping on the specified identifier runnable.
570 */
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571static void
572_wakeup(void *ident, int count)
984263bc 573{
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574 struct slpquehead *qp;
575 struct thread *td;
576 struct thread *ntd;
577 struct proc *p;
984263bc 578 int s;
f1d1c3fa 579 int id = LOOKUP(ident);
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580
581 s = splhigh();
f1d1c3fa 582 qp = &slpque[id];
984263bc 583restart:
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584 for (td = TAILQ_FIRST(qp); td != NULL; td = ntd) {
585 ntd = TAILQ_NEXT(td, td_threadq);
586 if (td->td_wchan == ident) {
587 TAILQ_REMOVE(qp, td, td_threadq);
588 td->td_wchan = NULL;
589 if ((p = td->td_proc) != NULL && p->p_stat == SSLEEP) {
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590 /* OPTIMIZED EXPANSION OF setrunnable(p); */
591 if (p->p_slptime > 1)
592 updatepri(p);
593 p->p_slptime = 0;
594 p->p_stat = SRUN;
595 if (p->p_flag & P_INMEM) {
596 setrunqueue(p);
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597 } else {
598 p->p_flag |= P_SWAPINREQ;
599 wakeup((caddr_t)&proc0);
600 }
601 /* END INLINE EXPANSION */
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602 } else if (p == NULL) {
603 lwkt_schedule(td);
984263bc 604 }
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605 if (--count == 0)
606 break;
607 goto restart;
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608 }
609 }
610 splx(s);
611}
612
984263bc 613void
0cfcada1 614wakeup(void *ident)
984263bc 615{
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616 _wakeup(ident, 0);
617}
984263bc 618
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619void
620wakeup_one(void *ident)
621{
622 _wakeup(ident, 1);
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623}
624
625/*
626 * The machine independent parts of mi_switch().
627 * Must be called at splstatclock() or higher.
628 */
629void
630mi_switch()
631{
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632 struct thread *td = curthread;
633 struct proc *p = td->td_proc; /* XXX */
634 struct rlimit *rlim;
984263bc 635 int x;
d16a8831 636 u_int64_t ttime;
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637
638 /*
639 * XXX this spl is almost unnecessary. It is partly to allow for
640 * sloppy callers that don't do it (issignal() via CURSIG() is the
641 * main offender). It is partly to work around a bug in the i386
642 * cpu_switch() (the ipl is not preserved). We ran for years
643 * without it. I think there was only a interrupt latency problem.
644 * The main caller, tsleep(), does an splx() a couple of instructions
645 * after calling here. The buggy caller, issignal(), usually calls
646 * here at spl0() and sometimes returns at splhigh(). The process
647 * then runs for a little too long at splhigh(). The ipl gets fixed
648 * when the process returns to user mode (or earlier).
649 *
650 * It would probably be better to always call here at spl0(). Callers
651 * are prepared to give up control to another process, so they must
652 * be prepared to be interrupted. The clock stuff here may not
653 * actually need splstatclock().
654 */
655 x = splstatclock();
8ad65e08 656 clear_resched();
984263bc 657
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658 /*
659 * Check if the process exceeds its cpu resource allocation.
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660 * If over max, kill it. Time spent in interrupts is not
661 * included. YYY 64 bit match is expensive. Ick.
984263bc 662 */
d16a8831 663 ttime = td->td_sticks + td->td_uticks;
984263bc 664 if (p->p_stat != SZOMB && p->p_limit->p_cpulimit != RLIM_INFINITY &&
d16a8831 665 ttime > p->p_limit->p_cpulimit) {
984263bc 666 rlim = &p->p_rlimit[RLIMIT_CPU];
d16a8831 667 if (ttime / (rlim_t)1000000 >= rlim->rlim_max) {
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668 killproc(p, "exceeded maximum CPU limit");
669 } else {
670 psignal(p, SIGXCPU);
671 if (rlim->rlim_cur < rlim->rlim_max) {
672 /* XXX: we should make a private copy */
673 rlim->rlim_cur += 5;
674 }
675 }
676 }
677
678 /*
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679 * Pick a new current process and record its start time. If we
680 * are in a SSTOPped state we deschedule ourselves. YYY this needs
681 * to be cleaned up, remember that LWKTs stay on their run queue
682 * which works differently then the user scheduler which removes
683 * the process from the runq when it runs it.
984263bc 684 */
12e4aaff 685 mycpu->gd_cnt.v_swtch++;
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686 if (p->p_stat == SSTOP)
687 lwkt_deschedule_self();
8ad65e08 688 lwkt_switch();
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689
690 splx(x);
691}
692
693/*
694 * Change process state to be runnable,
695 * placing it on the run queue if it is in memory,
696 * and awakening the swapper if it isn't in memory.
697 */
698void
0cfcada1 699setrunnable(struct proc *p)
984263bc 700{
0cfcada1 701 int s;
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702
703 s = splhigh();
704 switch (p->p_stat) {
705 case 0:
706 case SRUN:
707 case SZOMB:
708 default:
709 panic("setrunnable");
710 case SSTOP:
711 case SSLEEP:
0cfcada1 712 unsleep(p->p_thread); /* e.g. when sending signals */
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713 break;
714
715 case SIDL:
716 break;
717 }
718 p->p_stat = SRUN;
719 if (p->p_flag & P_INMEM)
720 setrunqueue(p);
721 splx(s);
722 if (p->p_slptime > 1)
723 updatepri(p);
724 p->p_slptime = 0;
725 if ((p->p_flag & P_INMEM) == 0) {
726 p->p_flag |= P_SWAPINREQ;
727 wakeup((caddr_t)&proc0);
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728 }
729}
730
731/*
732 * Change the process state to NOT be runnable, removing it from the run
733 * queue. If P_CURPROC is not set and we are in SRUN the process is on the
734 * run queue (If P_INMEM is not set then it isn't because it is swapped).
735 */
736void
737clrrunnable(struct proc *p, int stat)
738{
739 int s;
740
741 s = splhigh();
742 switch(p->p_stat) {
743 case SRUN:
a2a5ad0d 744 if (p->p_flag & P_ONRUNQ)
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745 remrunqueue(p);
746 break;
747 default:
748 break;
749 }
750 p->p_stat = stat;
751 splx(s);
752}
753
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754/*
755 * Compute the priority of a process when running in user mode.
756 * Arrange to reschedule if the resulting priority is better
757 * than that of the current process.
758 */
759void
26a0694b 760resetpriority(struct proc *p)
984263bc 761{
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762 unsigned int newpriority;
763 int opq;
764 int npq;
765
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766 /*
767 * Set p_priority for general process comparisons
768 */
769 switch(p->p_rtprio.type) {
770 case RTP_PRIO_REALTIME:
771 p->p_priority = PRIBASE_REALTIME + p->p_rtprio.prio;
772 return;
773 case RTP_PRIO_NORMAL:
774 break;
775 case RTP_PRIO_IDLE:
776 p->p_priority = PRIBASE_IDLE + p->p_rtprio.prio;
26a0694b 777 return;
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778 case RTP_PRIO_THREAD:
779 p->p_priority = PRIBASE_THREAD + p->p_rtprio.prio;
780 return;
781 }
782
783 /*
784 * NORMAL priorities fall through. These are based on niceness
785 * and cpu use.
786 */
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787 newpriority = NICE_ADJUST(p->p_nice - PRIO_MIN) +
788 p->p_estcpu / ESTCPURAMP;
26a0694b 789 newpriority = min(newpriority, MAXPRI);
26a0694b 790 npq = newpriority / PPQ;
d6dd2af9 791 crit_enter();
435ff993 792 opq = (p->p_priority & PRIMASK) / PPQ;
a2a5ad0d 793 if (p->p_stat == SRUN && (p->p_flag & P_ONRUNQ) && opq != npq) {
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794 /*
795 * We have to move the process to another queue
796 */
797 remrunqueue(p);
435ff993 798 p->p_priority = PRIBASE_NORMAL + newpriority;
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799 setrunqueue(p);
800 } else {
801 /*
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802 * We can just adjust the priority and it will be picked
803 * up later.
26a0694b 804 */
a2a5ad0d 805 KKASSERT(opq == npq || (p->p_flag & P_ONRUNQ) == 0);
435ff993 806 p->p_priority = PRIBASE_NORMAL + newpriority;
984263bc 807 }
d6dd2af9 808 crit_exit();
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809}
810
811/*
812 * Compute a tenex style load average of a quantity on
813 * 1, 5 and 15 minute intervals.
814 */
815static void
816loadav(void *arg)
817{
818 int i, nrun;
819 struct loadavg *avg;
820 struct proc *p;
821
822 avg = &averunnable;
823 nrun = 0;
f62004ad 824 FOREACH_PROC_IN_SYSTEM(p) {
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825 switch (p->p_stat) {
826 case SRUN:
827 case SIDL:
828 nrun++;
829 }
830 }
831 for (i = 0; i < 3; i++)
832 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] +
833 nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT;
834
835 /*
836 * Schedule the next update to occur after 5 seconds, but add a
837 * random variation to avoid synchronisation with processes that
838 * run at regular intervals.
839 */
840 callout_reset(&loadav_callout, hz * 4 + (int)(random() % (hz * 2 + 1)),
841 loadav, NULL);
842}
843
844/* ARGSUSED */
845static void
6656cd91 846sched_setup(void *dummy)
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847{
848
849 callout_init(&loadav_callout);
850
851 /* Kick off timeout driven events by calling first time. */
852 roundrobin(NULL);
853 schedcpu(NULL);
854 loadav(NULL);
855}
856
857/*
858 * We adjust the priority of the current process. The priority of
859 * a process gets worse as it accumulates CPU time. The cpu usage
860 * estimator (p_estcpu) is increased here. resetpriority() will
861 * compute a different priority each time p_estcpu increases by
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862 * INVERSE_ESTCPU_WEIGHT * (until MAXPRI is reached).
863 *
864 * The cpu usage estimator ramps up quite quickly when the process is
865 * running (linearly), and decays away exponentially, at a rate which
866 * is proportionally slower when the system is busy. The basic principle
867 * is that the system will 90% forget that the process used a lot of CPU
868 * time in 5 * loadav seconds. This causes the system to favor processes
869 * which haven't run much recently, and to round-robin among other processes.
435ff993 870 *
88c4d2f6
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871 * WARNING! called from a fast-int or an IPI, the MP lock MIGHT NOT BE HELD
872 * and we cannot block.
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873 */
874void
88c4d2f6 875schedulerclock(void *dummy)
984263bc 876{
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877 struct thread *td;
878 struct proc *p;
879
880 td = curthread;
881 if ((p = td->td_proc) != NULL) {
882 p->p_cpticks++;
883 p->p_estcpu = ESTCPULIM(p->p_estcpu + 1);
884 if ((p->p_estcpu % PPQ) == 0 && try_mplock()) {
885 resetpriority(p);
886 rel_mplock();
887 }
888 }
984263bc 889}
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890
891static
892void
893crit_panicints(void)
894{
895 int s;
896 int cpri;
897
898 s = splhigh();
899 cpri = crit_panic_save();
900 splx(safepri);
901 crit_panic_restore(cpri);
902 splx(s);
903}
904