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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: *
34: * @(#)kern_synch.c 7.18 (Berkeley) 6/27/91
1.1.1.3 ! root 35: *
! 36: * PATCHES MAGIC LEVEL PATCH THAT GOT US HERE
! 37: * -------------------- ----- ----------------------
! 38: * CURRENT PATCH LEVEL: 1 00077
! 39: * -------------------- ----- ----------------------
! 40: *
! 41: * 11 Dec 92 Williams Jolitz Fixed panic:remrq hangs
1.1 root 42: */
43:
44: #include "param.h"
45: #include "systm.h"
46: #include "proc.h"
47: #include "kernel.h"
48: #include "buf.h"
49: #include "signalvar.h"
50: #include "resourcevar.h"
51:
52: #include "machine/cpu.h"
53:
54: u_char curpri; /* usrpri of curproc */
55:
56: /*
57: * Force switch among equal priority processes every 100ms.
58: */
59: roundrobin()
60: {
61:
62: need_resched();
63: timeout(roundrobin, (caddr_t)0, hz / 10);
64: }
65:
66: /*
67: * constants for digital decay and forget
68: * 90% of (p_cpu) usage in 5*loadav time
69: * 95% of (p_pctcpu) usage in 60 seconds (load insensitive)
70: * Note that, as ps(1) mentions, this can let percentages
71: * total over 100% (I've seen 137.9% for 3 processes).
72: *
73: * Note that hardclock updates p_cpu and p_cpticks independently.
74: *
75: * We wish to decay away 90% of p_cpu in (5 * loadavg) seconds.
76: * That is, the system wants to compute a value of decay such
77: * that the following for loop:
78: * for (i = 0; i < (5 * loadavg); i++)
79: * p_cpu *= decay;
80: * will compute
81: * p_cpu *= 0.1;
82: * for all values of loadavg:
83: *
84: * Mathematically this loop can be expressed by saying:
85: * decay ** (5 * loadavg) ~= .1
86: *
87: * The system computes decay as:
88: * decay = (2 * loadavg) / (2 * loadavg + 1)
89: *
90: * We wish to prove that the system's computation of decay
91: * will always fulfill the equation:
92: * decay ** (5 * loadavg) ~= .1
93: *
94: * If we compute b as:
95: * b = 2 * loadavg
96: * then
97: * decay = b / (b + 1)
98: *
99: * We now need to prove two things:
100: * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1)
101: * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg)
102: *
103: * Facts:
104: * For x close to zero, exp(x) =~ 1 + x, since
105: * exp(x) = 0! + x**1/1! + x**2/2! + ... .
106: * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b.
107: * For x close to zero, ln(1+x) =~ x, since
108: * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1
109: * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1).
110: * ln(.1) =~ -2.30
111: *
112: * Proof of (1):
113: * Solve (factor)**(power) =~ .1 given power (5*loadav):
114: * solving for factor,
115: * ln(factor) =~ (-2.30/5*loadav), or
116: * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) =
117: * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED
118: *
119: * Proof of (2):
120: * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)):
121: * solving for power,
122: * power*ln(b/(b+1)) =~ -2.30, or
123: * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED
124: *
125: * Actual power values for the implemented algorithm are as follows:
126: * loadav: 1 2 3 4
127: * power: 5.68 10.32 14.94 19.55
128: */
129:
130: /* calculations for digital decay to forget 90% of usage in 5*loadav sec */
131: #define loadfactor(loadav) (2 * (loadav))
132: #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE))
133:
134: /* decay 95% of `p_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */
135: fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
136:
137: /*
138: * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the
139: * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below
140: * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT).
141: *
142: * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used:
143: * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits).
144: *
145: * If you dont want to bother with the faster/more-accurate formula, you
146: * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate
147: * (more general) method of calculating the %age of CPU used by a process.
148: */
149: #define CCPU_SHIFT 11
150:
151: /*
152: * Recompute process priorities, once a second
153: */
154: schedcpu()
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: */
220: updatepri(p)
221: register struct proc *p;
222: {
223: register unsigned int newcpu = p->p_cpu;
224: register fixpt_t loadfac = loadfactor(averunnable[0]);
225:
226: if (p->p_slptime > 5 * loadfac)
227: p->p_cpu = 0;
228: else {
229: p->p_slptime--; /* the first time was done in schedcpu */
230: while (newcpu && --p->p_slptime)
231: newcpu = (int) decay_cpu(loadfac, newcpu);
232: p->p_cpu = min(newcpu, UCHAR_MAX);
233: }
234: setpri(p);
235: }
236:
237: #define SQSIZE 0100 /* Must be power of 2 */
238: #define HASH(x) (( (int) x >> 5) & (SQSIZE-1))
239: struct slpque {
240: struct proc *sq_head;
241: struct proc **sq_tailp;
242: } slpque[SQSIZE];
243:
244: /*
245: * During autoconfiguration or after a panic, a sleep will simply
246: * lower the priority briefly to allow interrupts, then return.
247: * The priority to be used (safepri) is machine-dependent, thus this
248: * value is initialized and maintained in the machine-dependent layers.
249: * This priority will typically be 0, or the lowest priority
250: * that is safe for use on the interrupt stack; it can be made
251: * higher to block network software interrupts after panics.
252: */
253: int safepri;
254:
255: /*
256: * General sleep call.
257: * Suspends current process until a wakeup is made on chan.
258: * The process will then be made runnable with priority pri.
259: * Sleeps at most timo/hz seconds (0 means no timeout).
260: * If pri includes PCATCH flag, signals are checked
261: * before and after sleeping, else signals are not checked.
262: * Returns 0 if awakened, EWOULDBLOCK if the timeout expires.
263: * If PCATCH is set and a signal needs to be delivered,
264: * ERESTART is returned if the current system call should be restarted
265: * if possible, and EINTR is returned if the system call should
266: * be interrupted by the signal (return EINTR).
267: */
268: tsleep(chan, pri, wmesg, timo)
269: caddr_t chan;
270: int pri;
271: char *wmesg;
272: int timo;
273: {
274: register struct proc *p = curproc;
275: register struct slpque *qp;
276: register s;
277: int sig, catch = pri & PCATCH;
278: extern int cold;
279: int endtsleep();
280:
281: s = splhigh();
282: if (cold || panicstr) {
283: /*
284: * After a panic, or during autoconfiguration,
285: * just give interrupts a chance, then just return;
286: * don't run any other procs or panic below,
287: * in case this is the idle process and already asleep.
288: */
289: splx(safepri);
290: splx(s);
291: return (0);
292: }
293: #ifdef DIAGNOSTIC
294: if (chan == 0 || p->p_stat != SRUN || p->p_rlink)
295: panic("tsleep");
296: #endif
297: p->p_wchan = chan;
298: p->p_wmesg = wmesg;
299: p->p_slptime = 0;
300: p->p_pri = pri & PRIMASK;
301: qp = &slpque[HASH(chan)];
302: if (qp->sq_head == 0)
303: qp->sq_head = p;
304: else
305: *qp->sq_tailp = p;
306: *(qp->sq_tailp = &p->p_link) = 0;
307: if (timo)
308: timeout(endtsleep, (caddr_t)p, timo);
309: /*
310: * We put ourselves on the sleep queue and start our timeout
311: * before calling CURSIG, as we could stop there, and a wakeup
312: * or a SIGCONT (or both) could occur while we were stopped.
313: * A SIGCONT would cause us to be marked as SSLEEP
314: * without resuming us, thus we must be ready for sleep
315: * when CURSIG is called. If the wakeup happens while we're
316: * stopped, p->p_wchan will be 0 upon return from CURSIG.
317: */
318: if (catch) {
319: p->p_flag |= SSINTR;
320: if (sig = CURSIG(p)) {
321: if (p->p_wchan)
322: unsleep(p);
323: p->p_stat = SRUN;
324: goto resume;
325: }
326: if (p->p_wchan == 0) {
327: catch = 0;
328: goto resume;
329: }
330: }
331: p->p_stat = SSLEEP;
332: p->p_stats->p_ru.ru_nvcsw++;
333: swtch();
1.1.1.2 root 334: #include "ddb.h"
335: #ifdef NDDB
336: /* handy breakpoint location after process "wakes" */
337: asm(".globl bpendtsleep ; bpendtsleep:");
338: #endif
1.1 root 339: resume:
340: curpri = p->p_usrpri;
341: splx(s);
342: p->p_flag &= ~SSINTR;
343: if (p->p_flag & STIMO) {
344: p->p_flag &= ~STIMO;
345: if (catch == 0 || sig == 0)
346: return (EWOULDBLOCK);
347: } else if (timo)
348: untimeout(endtsleep, (caddr_t)p);
349: if (catch && (sig != 0 || (sig = CURSIG(p)))) {
350: if (p->p_sigacts->ps_sigintr & sigmask(sig))
351: return (EINTR);
352: return (ERESTART);
353: }
354: return (0);
355: }
356:
357: /*
358: * Implement timeout for tsleep.
359: * If process hasn't been awakened (wchan non-zero),
360: * set timeout flag and undo the sleep. If proc
361: * is stopped, just unsleep so it will remain stopped.
362: */
363: endtsleep(p)
364: register struct proc *p;
365: {
366: int s = splhigh();
367:
368: if (p->p_wchan) {
369: if (p->p_stat == SSLEEP)
370: setrun(p);
371: else
372: unsleep(p);
373: p->p_flag |= STIMO;
374: }
375: splx(s);
376: }
377:
378: /*
379: * Short-term, non-interruptable sleep.
380: */
381: sleep(chan, pri)
382: caddr_t chan;
383: int pri;
384: {
385: register struct proc *p = curproc;
386: register struct slpque *qp;
387: register s;
388: extern int cold;
389:
390: #ifdef DIAGNOSTIC
391: if (pri > PZERO) {
392: printf("sleep called with pri %d > PZERO, wchan: %x\n",
393: pri, chan);
394: panic("old sleep");
395: }
396: #endif
397: s = splhigh();
398: if (cold || panicstr) {
399: /*
400: * After a panic, or during autoconfiguration,
401: * just give interrupts a chance, then just return;
402: * don't run any other procs or panic below,
403: * in case this is the idle process and already asleep.
404: */
405: splx(safepri);
406: splx(s);
407: return;
408: }
409: #ifdef DIAGNOSTIC
410: if (chan==0 || p->p_stat != SRUN || p->p_rlink)
411: panic("sleep");
412: #endif
413: p->p_wchan = chan;
414: p->p_wmesg = NULL;
415: p->p_slptime = 0;
416: p->p_pri = pri;
417: qp = &slpque[HASH(chan)];
418: if (qp->sq_head == 0)
419: qp->sq_head = p;
420: else
421: *qp->sq_tailp = p;
422: *(qp->sq_tailp = &p->p_link) = 0;
423: p->p_stat = SSLEEP;
424: p->p_stats->p_ru.ru_nvcsw++;
425: swtch();
1.1.1.2 root 426: #ifdef NDDB
427: /* handy breakpoint location after process "wakes" */
428: asm(".globl bpendsleep ; bpendsleep:");
429: #endif
1.1 root 430: curpri = p->p_usrpri;
431: splx(s);
432: }
433:
434: /*
435: * Remove a process from its wait queue
436: */
437: unsleep(p)
438: register struct proc *p;
439: {
440: register struct slpque *qp;
441: register struct proc **hp;
442: int s;
443:
444: s = splhigh();
445: if (p->p_wchan) {
446: hp = &(qp = &slpque[HASH(p->p_wchan)])->sq_head;
447: while (*hp != p)
448: hp = &(*hp)->p_link;
449: *hp = p->p_link;
450: if (qp->sq_tailp == &p->p_link)
451: qp->sq_tailp = hp;
452: p->p_wchan = 0;
453: }
454: splx(s);
455: }
456:
457: /*
458: * Wakeup on "chan"; set all processes
459: * sleeping on chan to run state.
460: */
461: wakeup(chan)
462: register caddr_t chan;
463: {
464: register struct slpque *qp;
465: register struct proc *p, **q;
466: int s;
467:
468: s = splhigh();
469: qp = &slpque[HASH(chan)];
470: restart:
471: for (q = &qp->sq_head; p = *q; ) {
472: #ifdef DIAGNOSTIC
473: if (p->p_rlink || p->p_stat != SSLEEP && p->p_stat != SSTOP)
474: panic("wakeup");
475: #endif
476: if (p->p_wchan == chan) {
477: p->p_wchan = 0;
478: *q = p->p_link;
479: if (qp->sq_tailp == &p->p_link)
480: qp->sq_tailp = q;
481: if (p->p_stat == SSLEEP) {
482: /* OPTIMIZED INLINE EXPANSION OF setrun(p) */
483: if (p->p_slptime > 1)
484: updatepri(p);
485: p->p_slptime = 0;
486: p->p_stat = SRUN;
487: if (p->p_flag & SLOAD)
488: setrq(p);
489: /*
490: * Since curpri is a usrpri,
491: * p->p_pri is always better than curpri.
492: */
493: if ((p->p_flag&SLOAD) == 0)
494: wakeup((caddr_t)&proc0);
495: else
496: need_resched();
497: /* END INLINE EXPANSION */
498: goto restart;
499: }
500: } else
501: q = &p->p_link;
502: }
503: splx(s);
504: }
505:
506: /*
507: * Initialize the (doubly-linked) run queues
508: * to be empty.
509: */
510: rqinit()
511: {
512: register int i;
513:
514: for (i = 0; i < NQS; i++)
515: qs[i].ph_link = qs[i].ph_rlink = (struct proc *)&qs[i];
516: }
517:
518: /*
519: * Change process state to be runnable,
520: * placing it on the run queue if it is in memory,
521: * and awakening the swapper if it isn't in memory.
522: */
523: setrun(p)
524: register struct proc *p;
525: {
526: register int s;
527:
528: s = splhigh();
529: switch (p->p_stat) {
530:
531: case 0:
532: case SWAIT:
533: case SRUN:
534: case SZOMB:
535: default:
536: panic("setrun");
537:
538: case SSTOP:
539: case SSLEEP:
540: unsleep(p); /* e.g. when sending signals */
541: break;
542:
543: case SIDL:
544: break;
545: }
546: p->p_stat = SRUN;
547: if (p->p_flag & SLOAD)
548: setrq(p);
549: splx(s);
550: if (p->p_slptime > 1)
551: updatepri(p);
552: p->p_slptime = 0;
553: if ((p->p_flag&SLOAD) == 0)
554: wakeup((caddr_t)&proc0);
555: else if (p->p_pri < curpri)
556: need_resched();
557: }
558:
559: /*
560: * Compute priority of process when running in user mode.
561: * Arrange to reschedule if the resulting priority
562: * is better than that of the current process.
563: */
564: setpri(p)
565: register struct proc *p;
566: {
567: register unsigned int newpri;
568:
569: newpri = PUSER + p->p_cpu / 4 + 2 * p->p_nice;
570: newpri = min(newpri, MAXPRI);
571: p->p_usrpri = newpri;
572: if (newpri < curpri)
573: need_resched();
574: }
1.1.1.2 root 575:
576: #ifdef NDDB
577: #define DDBFUNC(s) ddb_##s
578: DDBFUNC(ps) () {
579: int np;
580: struct proc *ap, *p, *pp;
581: np = nprocs;
582: p = ap = allproc;
583: printf(" pid proc addr uid ppid pgrp flag stat comm wchan\n");
584: while (--np >= 0) {
585: pp = p->p_pptr;
586: if (pp == 0)
587: pp = p;
588: if (p->p_stat) {
589: printf("%5d %06x %06x %3d %5d %5d %06x %d %s ",
590: p->p_pid, ap, p->p_addr, p->p_cred->p_ruid, pp->p_pid,
591: p->p_pgrp->pg_id, p->p_flag, p->p_stat,
592: p->p_comm);
593: if (p->p_wchan) {
594: if (p->p_wmesg)
595: printf("%s ", p->p_wmesg);
596: printf("%x", p->p_wchan);
597: }
598: printf("\n");
599: }
600: ap = p->p_nxt;
601: if (ap == 0 && np > 0)
602: ap = zombproc;
603: p = ap;
604: }
605: }
606: #endif
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