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1.1 root 1: /*-
2: * Copyright (c) 1982, 1986, 1990 The Regents of the University of California.
3: * Copyright (c) 1991 The Regents of the University of California.
4: * All rights reserved.
5: *
6: * Redistribution and use in source and binary forms, with or without
7: * modification, are permitted provided that the following conditions
8: * are met:
9: * 1. Redistributions of source code must retain the above copyright
10: * notice, this list of conditions and the following disclaimer.
11: * 2. Redistributions in binary form must reproduce the above copyright
12: * notice, this list of conditions and the following disclaimer in the
13: * documentation and/or other materials provided with the distribution.
14: * 3. All advertising materials mentioning features or use of this software
15: * must display the following acknowledgement:
16: * This product includes software developed by the University of
17: * California, Berkeley and its contributors.
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: *
1.1.1.4 ! root 34: * from: @(#)kern_synch.c 7.18 (Berkeley) 6/27/91
! 35: * kern_synch.c,v 1.8 1993/06/27 06:22:32 andrew Exp
1.1 root 36: */
37:
38: #include "param.h"
39: #include "systm.h"
40: #include "proc.h"
41: #include "kernel.h"
42: #include "buf.h"
43: #include "signalvar.h"
44: #include "resourcevar.h"
45:
46: #include "machine/cpu.h"
47:
1.1.1.4 ! root 48: void endtsleep __P((struct proc *p));
! 49:
1.1 root 50: u_char curpri; /* usrpri of curproc */
51:
52: /*
53: * Force switch among equal priority processes every 100ms.
54: */
1.1.1.4 ! root 55: /* ARGSUSED */
! 56: void
! 57: roundrobin(caddr_t arg)
1.1 root 58: {
59:
60: need_resched();
61: timeout(roundrobin, (caddr_t)0, hz / 10);
62: }
63:
64: /*
65: * constants for digital decay and forget
66: * 90% of (p_cpu) usage in 5*loadav time
67: * 95% of (p_pctcpu) usage in 60 seconds (load insensitive)
68: * Note that, as ps(1) mentions, this can let percentages
69: * total over 100% (I've seen 137.9% for 3 processes).
70: *
71: * Note that hardclock updates p_cpu and p_cpticks independently.
72: *
73: * We wish to decay away 90% of p_cpu in (5 * loadavg) seconds.
74: * That is, the system wants to compute a value of decay such
75: * that the following for loop:
76: * for (i = 0; i < (5 * loadavg); i++)
77: * p_cpu *= decay;
78: * will compute
79: * p_cpu *= 0.1;
80: * for all values of loadavg:
81: *
82: * Mathematically this loop can be expressed by saying:
83: * decay ** (5 * loadavg) ~= .1
84: *
85: * The system computes decay as:
86: * decay = (2 * loadavg) / (2 * loadavg + 1)
87: *
88: * We wish to prove that the system's computation of decay
89: * will always fulfill the equation:
90: * decay ** (5 * loadavg) ~= .1
91: *
92: * If we compute b as:
93: * b = 2 * loadavg
94: * then
95: * decay = b / (b + 1)
96: *
97: * We now need to prove two things:
98: * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1)
99: * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg)
100: *
101: * Facts:
102: * For x close to zero, exp(x) =~ 1 + x, since
103: * exp(x) = 0! + x**1/1! + x**2/2! + ... .
104: * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b.
105: * For x close to zero, ln(1+x) =~ x, since
106: * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1
107: * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1).
108: * ln(.1) =~ -2.30
109: *
110: * Proof of (1):
111: * Solve (factor)**(power) =~ .1 given power (5*loadav):
112: * solving for factor,
113: * ln(factor) =~ (-2.30/5*loadav), or
114: * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) =
115: * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED
116: *
117: * Proof of (2):
118: * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)):
119: * solving for power,
120: * power*ln(b/(b+1)) =~ -2.30, or
121: * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED
122: *
123: * Actual power values for the implemented algorithm are as follows:
124: * loadav: 1 2 3 4
125: * power: 5.68 10.32 14.94 19.55
126: */
127:
128: /* calculations for digital decay to forget 90% of usage in 5*loadav sec */
129: #define loadfactor(loadav) (2 * (loadav))
130: #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE))
131:
132: /* decay 95% of `p_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */
133: fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
134:
135: /*
136: * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the
137: * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below
138: * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT).
139: *
140: * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used:
141: * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits).
142: *
143: * If you dont want to bother with the faster/more-accurate formula, you
144: * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate
145: * (more general) method of calculating the %age of CPU used by a process.
146: */
147: #define CCPU_SHIFT 11
148:
149: /*
150: * Recompute process priorities, once a second
151: */
1.1.1.4 ! root 152: /* ARGSUSED */
! 153: void
! 154: schedcpu(caddr_t arg)
1.1 root 155: {
156: register fixpt_t loadfac = loadfactor(averunnable[0]);
157: register struct proc *p;
158: register int s;
159: register unsigned int newcpu;
160:
161: wakeup((caddr_t)&lbolt);
162: for (p = allproc; p != NULL; p = p->p_nxt) {
163: /*
164: * Increment time in/out of memory and sleep time
165: * (if sleeping). We ignore overflow; with 16-bit int's
166: * (remember them?) overflow takes 45 days.
167: */
168: p->p_time++;
169: if (p->p_stat == SSLEEP || p->p_stat == SSTOP)
170: p->p_slptime++;
171: p->p_pctcpu = (p->p_pctcpu * ccpu) >> FSHIFT;
172: /*
173: * If the process has slept the entire second,
174: * stop recalculating its priority until it wakes up.
175: */
176: if (p->p_slptime > 1)
177: continue;
178: /*
179: * p_pctcpu is only for ps.
180: */
181: #if (FSHIFT >= CCPU_SHIFT)
182: p->p_pctcpu += (hz == 100)?
183: ((fixpt_t) p->p_cpticks) << (FSHIFT - CCPU_SHIFT):
184: 100 * (((fixpt_t) p->p_cpticks)
185: << (FSHIFT - CCPU_SHIFT)) / hz;
186: #else
187: p->p_pctcpu += ((FSCALE - ccpu) *
188: (p->p_cpticks * FSCALE / hz)) >> FSHIFT;
189: #endif
190: p->p_cpticks = 0;
191: newcpu = (u_int) decay_cpu(loadfac, p->p_cpu) + p->p_nice;
192: p->p_cpu = min(newcpu, UCHAR_MAX);
193: setpri(p);
194: s = splhigh(); /* prevent state changes */
195: if (p->p_pri >= PUSER) {
196: #define PPQ (128 / NQS) /* priorities per queue */
197: if ((p != curproc) &&
198: p->p_stat == SRUN &&
1.1.1.3 root 199: (p->p_flag & (SLOAD|SWEXIT)) == SLOAD &&
1.1 root 200: (p->p_pri / PPQ) != (p->p_usrpri / PPQ)) {
201: remrq(p);
202: p->p_pri = p->p_usrpri;
203: setrq(p);
204: } else
205: p->p_pri = p->p_usrpri;
206: }
207: splx(s);
208: }
209: vmmeter();
210: if (bclnlist != NULL)
211: wakeup((caddr_t)pageproc);
212: timeout(schedcpu, (caddr_t)0, hz);
213: }
214:
215: /*
216: * Recalculate the priority of a process after it has slept for a while.
217: * For all load averages >= 1 and max p_cpu of 255, sleeping for at least
218: * six times the loadfactor will decay p_cpu to zero.
219: */
1.1.1.4 ! root 220: void
1.1 root 221: updatepri(p)
222: register struct proc *p;
223: {
224: register unsigned int newcpu = p->p_cpu;
225: register fixpt_t loadfac = loadfactor(averunnable[0]);
226:
227: if (p->p_slptime > 5 * loadfac)
228: p->p_cpu = 0;
229: else {
230: p->p_slptime--; /* the first time was done in schedcpu */
231: while (newcpu && --p->p_slptime)
232: newcpu = (int) decay_cpu(loadfac, newcpu);
233: p->p_cpu = min(newcpu, UCHAR_MAX);
234: }
235: setpri(p);
236: }
237:
238: #define SQSIZE 0100 /* Must be power of 2 */
239: #define HASH(x) (( (int) x >> 5) & (SQSIZE-1))
240: struct slpque {
241: struct proc *sq_head;
242: struct proc **sq_tailp;
243: } slpque[SQSIZE];
244:
245: /*
246: * During autoconfiguration or after a panic, a sleep will simply
247: * lower the priority briefly to allow interrupts, then return.
248: * The priority to be used (safepri) is machine-dependent, thus this
249: * value is initialized and maintained in the machine-dependent layers.
250: * This priority will typically be 0, or the lowest priority
251: * that is safe for use on the interrupt stack; it can be made
252: * higher to block network software interrupts after panics.
253: */
254: int safepri;
255:
256: /*
257: * General sleep call.
258: * Suspends current process until a wakeup is made on chan.
259: * The process will then be made runnable with priority pri.
260: * Sleeps at most timo/hz seconds (0 means no timeout).
261: * If pri includes PCATCH flag, signals are checked
262: * before and after sleeping, else signals are not checked.
263: * Returns 0 if awakened, EWOULDBLOCK if the timeout expires.
264: * If PCATCH is set and a signal needs to be delivered,
265: * ERESTART is returned if the current system call should be restarted
266: * if possible, and EINTR is returned if the system call should
267: * be interrupted by the signal (return EINTR).
268: */
1.1.1.4 ! root 269: int
! 270: #ifdef __STDC__
! 271: tsleep(caddr_t chan, int pri, const char *wmesg, int timo)
! 272: #else
1.1 root 273: tsleep(chan, pri, wmesg, timo)
274: caddr_t chan;
275: int pri;
276: char *wmesg;
277: int timo;
1.1.1.4 ! root 278: #endif
1.1 root 279: {
280: register struct proc *p = curproc;
281: register struct slpque *qp;
282: register s;
283: int sig, catch = pri & PCATCH;
284: extern int cold;
285:
286: s = splhigh();
287: if (cold || panicstr) {
288: /*
289: * After a panic, or during autoconfiguration,
290: * just give interrupts a chance, then just return;
291: * don't run any other procs or panic below,
292: * in case this is the idle process and already asleep.
293: */
294: splx(safepri);
295: splx(s);
296: return (0);
297: }
298: #ifdef DIAGNOSTIC
299: if (chan == 0 || p->p_stat != SRUN || p->p_rlink)
300: panic("tsleep");
301: #endif
302: p->p_wchan = chan;
303: p->p_wmesg = wmesg;
304: p->p_slptime = 0;
305: p->p_pri = pri & PRIMASK;
306: qp = &slpque[HASH(chan)];
307: if (qp->sq_head == 0)
308: qp->sq_head = p;
309: else
310: *qp->sq_tailp = p;
311: *(qp->sq_tailp = &p->p_link) = 0;
312: if (timo)
1.1.1.4 ! root 313: timeout((timeout_t)endtsleep, (caddr_t)p, timo);
1.1 root 314: /*
315: * We put ourselves on the sleep queue and start our timeout
316: * before calling CURSIG, as we could stop there, and a wakeup
317: * or a SIGCONT (or both) could occur while we were stopped.
318: * A SIGCONT would cause us to be marked as SSLEEP
319: * without resuming us, thus we must be ready for sleep
320: * when CURSIG is called. If the wakeup happens while we're
321: * stopped, p->p_wchan will be 0 upon return from CURSIG.
322: */
323: if (catch) {
324: p->p_flag |= SSINTR;
325: if (sig = CURSIG(p)) {
326: if (p->p_wchan)
327: unsleep(p);
328: p->p_stat = SRUN;
329: goto resume;
330: }
331: if (p->p_wchan == 0) {
332: catch = 0;
333: goto resume;
334: }
335: }
336: p->p_stat = SSLEEP;
337: p->p_stats->p_ru.ru_nvcsw++;
338: swtch();
1.1.1.4 ! root 339: #ifdef DDB
1.1.1.2 root 340: /* handy breakpoint location after process "wakes" */
341: asm(".globl bpendtsleep ; bpendtsleep:");
342: #endif
1.1 root 343: resume:
344: curpri = p->p_usrpri;
345: splx(s);
346: p->p_flag &= ~SSINTR;
347: if (p->p_flag & STIMO) {
348: p->p_flag &= ~STIMO;
349: if (catch == 0 || sig == 0)
350: return (EWOULDBLOCK);
351: } else if (timo)
1.1.1.4 ! root 352: untimeout((timeout_t)endtsleep, (caddr_t)p);
1.1 root 353: if (catch && (sig != 0 || (sig = CURSIG(p)))) {
354: if (p->p_sigacts->ps_sigintr & sigmask(sig))
355: return (EINTR);
356: return (ERESTART);
357: }
358: return (0);
359: }
360:
361: /*
362: * Implement timeout for tsleep.
363: * If process hasn't been awakened (wchan non-zero),
364: * set timeout flag and undo the sleep. If proc
365: * is stopped, just unsleep so it will remain stopped.
366: */
1.1.1.4 ! root 367: void
1.1 root 368: endtsleep(p)
369: register struct proc *p;
370: {
371: int s = splhigh();
372:
373: if (p->p_wchan) {
374: if (p->p_stat == SSLEEP)
375: setrun(p);
376: else
377: unsleep(p);
378: p->p_flag |= STIMO;
379: }
380: splx(s);
381: }
382:
383: /*
384: * Short-term, non-interruptable sleep.
385: */
1.1.1.4 ! root 386: void
1.1 root 387: sleep(chan, pri)
388: caddr_t chan;
389: int pri;
390: {
391: register struct proc *p = curproc;
392: register struct slpque *qp;
393: register s;
394: extern int cold;
395:
396: #ifdef DIAGNOSTIC
397: if (pri > PZERO) {
398: printf("sleep called with pri %d > PZERO, wchan: %x\n",
399: pri, chan);
400: panic("old sleep");
401: }
402: #endif
403: s = splhigh();
404: if (cold || panicstr) {
405: /*
406: * After a panic, or during autoconfiguration,
407: * just give interrupts a chance, then just return;
408: * don't run any other procs or panic below,
409: * in case this is the idle process and already asleep.
410: */
411: splx(safepri);
412: splx(s);
413: return;
414: }
415: #ifdef DIAGNOSTIC
416: if (chan==0 || p->p_stat != SRUN || p->p_rlink)
417: panic("sleep");
418: #endif
419: p->p_wchan = chan;
420: p->p_wmesg = NULL;
421: p->p_slptime = 0;
422: p->p_pri = pri;
423: qp = &slpque[HASH(chan)];
424: if (qp->sq_head == 0)
425: qp->sq_head = p;
426: else
427: *qp->sq_tailp = p;
428: *(qp->sq_tailp = &p->p_link) = 0;
429: p->p_stat = SSLEEP;
430: p->p_stats->p_ru.ru_nvcsw++;
431: swtch();
1.1.1.4 ! root 432: #ifdef DDB
1.1.1.2 root 433: /* handy breakpoint location after process "wakes" */
434: asm(".globl bpendsleep ; bpendsleep:");
435: #endif
1.1 root 436: curpri = p->p_usrpri;
437: splx(s);
438: }
439:
440: /*
441: * Remove a process from its wait queue
442: */
1.1.1.4 ! root 443: void
1.1 root 444: unsleep(p)
445: register struct proc *p;
446: {
447: register struct slpque *qp;
448: register struct proc **hp;
449: int s;
450:
451: s = splhigh();
452: if (p->p_wchan) {
453: hp = &(qp = &slpque[HASH(p->p_wchan)])->sq_head;
454: while (*hp != p)
455: hp = &(*hp)->p_link;
456: *hp = p->p_link;
457: if (qp->sq_tailp == &p->p_link)
458: qp->sq_tailp = hp;
459: p->p_wchan = 0;
460: }
461: splx(s);
462: }
463:
464: /*
465: * Wakeup on "chan"; set all processes
466: * sleeping on chan to run state.
467: */
1.1.1.4 ! root 468: void
1.1 root 469: wakeup(chan)
470: register caddr_t chan;
471: {
472: register struct slpque *qp;
473: register struct proc *p, **q;
474: int s;
475:
476: s = splhigh();
477: qp = &slpque[HASH(chan)];
478: restart:
479: for (q = &qp->sq_head; p = *q; ) {
480: #ifdef DIAGNOSTIC
481: if (p->p_rlink || p->p_stat != SSLEEP && p->p_stat != SSTOP)
482: panic("wakeup");
483: #endif
484: if (p->p_wchan == chan) {
485: p->p_wchan = 0;
486: *q = p->p_link;
487: if (qp->sq_tailp == &p->p_link)
488: qp->sq_tailp = q;
489: if (p->p_stat == SSLEEP) {
490: /* OPTIMIZED INLINE EXPANSION OF setrun(p) */
491: if (p->p_slptime > 1)
492: updatepri(p);
493: p->p_slptime = 0;
494: p->p_stat = SRUN;
495: if (p->p_flag & SLOAD)
496: setrq(p);
497: /*
498: * Since curpri is a usrpri,
499: * p->p_pri is always better than curpri.
500: */
501: if ((p->p_flag&SLOAD) == 0)
502: wakeup((caddr_t)&proc0);
503: else
504: need_resched();
505: /* END INLINE EXPANSION */
506: goto restart;
507: }
508: } else
509: q = &p->p_link;
510: }
511: splx(s);
512: }
513:
514: /*
515: * Initialize the (doubly-linked) run queues
516: * to be empty.
517: */
1.1.1.4 ! root 518: void
1.1 root 519: rqinit()
520: {
521: register int i;
522:
523: for (i = 0; i < NQS; i++)
524: qs[i].ph_link = qs[i].ph_rlink = (struct proc *)&qs[i];
525: }
526:
527: /*
528: * Change process state to be runnable,
529: * placing it on the run queue if it is in memory,
530: * and awakening the swapper if it isn't in memory.
531: */
1.1.1.4 ! root 532: void
1.1 root 533: setrun(p)
534: register struct proc *p;
535: {
536: register int s;
537:
538: s = splhigh();
539: switch (p->p_stat) {
540:
541: case 0:
542: case SWAIT:
543: case SRUN:
544: case SZOMB:
545: default:
546: panic("setrun");
547:
548: case SSTOP:
549: case SSLEEP:
550: unsleep(p); /* e.g. when sending signals */
551: break;
552:
553: case SIDL:
554: break;
555: }
556: p->p_stat = SRUN;
557: if (p->p_flag & SLOAD)
558: setrq(p);
559: splx(s);
560: if (p->p_slptime > 1)
561: updatepri(p);
562: p->p_slptime = 0;
563: if ((p->p_flag&SLOAD) == 0)
564: wakeup((caddr_t)&proc0);
565: else if (p->p_pri < curpri)
566: need_resched();
567: }
568:
569: /*
570: * Compute priority of process when running in user mode.
571: * Arrange to reschedule if the resulting priority
572: * is better than that of the current process.
573: */
1.1.1.4 ! root 574: void
1.1 root 575: setpri(p)
576: register struct proc *p;
577: {
578: register unsigned int newpri;
579:
580: newpri = PUSER + p->p_cpu / 4 + 2 * p->p_nice;
581: newpri = min(newpri, MAXPRI);
582: p->p_usrpri = newpri;
583: if (newpri < curpri)
584: need_resched();
585: }
1.1.1.2 root 586:
1.1.1.4 ! root 587: #ifdef DDB
! 588: void db_show_all_procs(long addr, int haddr, int count, char *modif)
! 589: {
! 590: int np;
! 591: struct proc *ap, *p, *pp;
! 592:
! 593: np = nprocs;
! 594: p = ap = allproc;
! 595: if (modif[0] == 'm')
! 596: db_printf(" pid proc addr map comm wchan\n");
! 597: else
! 598: db_printf(" pid proc addr uid ppid pgrp flag stat comm wchan\n");
1.1.1.2 root 599: while (--np >= 0) {
1.1.1.4 ! root 600: pp = p->p_pptr;
! 601: if (pp == 0)
! 602: pp = p;
! 603: if (p->p_stat) {
! 604: if (modif[0] == 'm') {
! 605: db_printf("%5d %06x %06x %06x %s ",
! 606: p->p_pid, ap, p->p_addr, p->p_vmspace, p->p_comm);
! 607: }
! 608: else {
! 609: db_printf("%5d %06x %06x %3d %5d %5d %06x %d %s ",
! 610: p->p_pid, ap, p->p_addr, p->p_cred->p_ruid,
! 611: pp->p_pid, p->p_pgrp->pg_id, p->p_flag,
! 612: p->p_stat, p->p_comm);
! 613: }
! 614: if (p->p_wchan) {
! 615: if (p->p_wmesg)
! 616: db_printf("%s ", p->p_wmesg);
! 617: db_printf("%x", p->p_wchan);
1.1.1.2 root 618: }
1.1.1.4 ! root 619: db_printf("\n");
1.1.1.2 root 620: }
1.1.1.4 ! root 621: ap = p->p_nxt;
! 622: if (ap == 0 && np > 0)
! 623: ap = zombproc;
! 624: p = ap;
1.1.1.2 root 625: }
626: }
627: #endif
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