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Annotation of kernel/bsd/kern/kern_clock.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.1 (the "License").  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License.
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: 
        !            25: /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
        !            26: /*-
        !            27:  * Copyright (c) 1982, 1986, 1991, 1993
        !            28:  *     The Regents of the University of California.  All rights reserved.
        !            29:  * (c) UNIX System Laboratories, Inc.
        !            30:  * All or some portions of this file are derived from material licensed
        !            31:  * to the University of California by American Telephone and Telegraph
        !            32:  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
        !            33:  * the permission of UNIX System Laboratories, Inc.
        !            34:  *
        !            35:  * Redistribution and use in source and binary forms, with or without
        !            36:  * modification, are permitted provided that the following conditions
        !            37:  * are met:
        !            38:  * 1. Redistributions of source code must retain the above copyright
        !            39:  *    notice, this list of conditions and the following disclaimer.
        !            40:  * 2. Redistributions in binary form must reproduce the above copyright
        !            41:  *    notice, this list of conditions and the following disclaimer in the
        !            42:  *    documentation and/or other materials provided with the distribution.
        !            43:  * 3. All advertising materials mentioning features or use of this software
        !            44:  *    must display the following acknowledgement:
        !            45:  *     This product includes software developed by the University of
        !            46:  *     California, Berkeley and its contributors.
        !            47:  * 4. Neither the name of the University nor the names of its contributors
        !            48:  *    may be used to endorse or promote products derived from this software
        !            49:  *    without specific prior written permission.
        !            50:  *
        !            51:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            52:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            53:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            54:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            55:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            56:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            57:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            58:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            59:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            60:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            61:  * SUCH DAMAGE.
        !            62:  *
        !            63:  *     @(#)kern_clock.c        8.5 (Berkeley) 1/21/94
        !            64:  */
        !            65: 
        !            66: #include <simple_clock.h>
        !            67: #include <cpus.h>
        !            68: 
        !            69: #include <machine/reg.h>
        !            70: #include <machine/spl.h>
        !            71: 
        !            72: #include <sys/param.h>
        !            73: #include <sys/systm.h>
        !            74: #include <sys/dkstat.h>
        !            75: #include <sys/callout.h>
        !            76: #include <sys/resourcevar.h>
        !            77: #include <sys/kernel.h>
        !            78: #include <sys/proc.h>
        !            79: 
        !            80: #ifdef GPROF
        !            81: #include <sys/gmon.h>
        !            82: #endif
        !            83: 
        !            84: #include <bsd/machine/cpu.h>
        !            85: 
        !            86: #include <kern/thread.h>
        !            87: #include <mach/machine.h>
        !            88: #include <kern/sched.h>
        !            89: #include <kern/thread_call.h>
        !            90: #include <mach/time_value.h>
        !            91: #include <kern/timer.h>
        !            92: #include <kern/xpr.h>
        !            93: 
        !            94: #include <kern/assert.h>
        !            95: 
        !            96: #include <mach/boolean.h>
        !            97: 
        !            98: /*
        !            99:  * Clock handling routines.
        !           100:  *
        !           101:  * This code is written to operate with two timers which run
        !           102:  * independently of each other. The main clock, running at hz
        !           103:  * times per second, is used to do scheduling and timeout calculations.
        !           104:  * The second timer does resource utilization estimation statistically
        !           105:  * based on the state of the machine phz times a second. Both functions
        !           106:  * can be performed by a single clock (ie hz == phz), however the 
        !           107:  * statistics will be much more prone to errors. Ideally a machine
        !           108:  * would have separate clocks measuring time spent in user state, system
        !           109:  * state, interrupt state, and idle state. These clocks would allow a non-
        !           110:  * approximate measure of resource utilization.
        !           111:  */
        !           112: #define BUMPTIME(t, usec) { \
        !           113:        register volatile struct timeval *tp = (t); \
        !           114:  \
        !           115:        tp->tv_usec += (usec); \
        !           116:        if (tp->tv_usec >= 1000000) { \
        !           117:                tp->tv_usec -= 1000000; \
        !           118:                tp->tv_sec++; \
        !           119:        } \
        !           120: }
        !           121: 
        !           122: /*
        !           123:  * The hz hardware interval timer.
        !           124:  * We update the events relating to real time.
        !           125:  * If this timer is also being used to gather statistics,
        !           126:  * we run through the statistics gathering routine as well.
        !           127:  */
        !           128: 
        !           129: #if    SIMPLE_CLOCK
        !           130: tvalspec_t     last_hardclock[NCPUS];
        !           131: #endif /* SIMPLE_CLOCK */
        !           132: 
        !           133: 
        !           134: /*ARGSUSED*/
        !           135: void
        !           136: hardclock(pc, ps)
        !           137:        int ps;
        !           138:        caddr_t pc;
        !           139: {
        !           140:        register struct callout *p1;
        !           141:        register struct proc *p;
        !           142:        register int s;
        !           143: #if    SIMPLE_CLOCK
        !           144:        tvalspec_t new_hardclock, delta_hardclock;
        !           145:        unsigned int myticks;
        !           146: #define        tick    myticks
        !           147: #endif /* SIMPLE_CLOCK */
        !           148: 
        !           149:        extern int tickdelta;
        !           150:        extern long timedelta;
        !           151:        register thread_t       thread;
        !           152: 
        !           153:        thread = current_thread();
        !           154: 
        !           155: #if    SIMPLE_CLOCK
        !           156:        /*
        !           157:         *      Simple hardware timer does not restart on overflow, hence
        !           158:         *      interrupts do not happen at a constant rate.  Must call
        !           159:         *      machine-dependent routine to find out how much time has
        !           160:         *      elapsed since last interrupt.
        !           161:         *
        !           162:         *      On NeXT we use SIMPLE_CLOCK because hardclock is called
        !           163:         *      at softint0 level, and although time won't drift, there's
        !           164:         *      a fair amount of "jitter". --mike
        !           165:         */
        !           166:        new_hardclock = clock_get_counter(System);
        !           167:        delta_hardclock = new_hardclock;
        !           168:        SUB_TVALSPEC(&delta_hardclock, &last_hardclock[cpu_number()]);
        !           169:        myticks = (delta_hardclock.tv_sec * USEC_PER_SEC) +
        !           170:                        (delta_hardclock.tv_nsec / NSEC_PER_USEC);
        !           171:        last_hardclock[cpu_number()] = new_hardclock;
        !           172: 
        !           173:        /*
        !           174:         *      NOTE: tick was #define'd to myticks above.
        !           175:         */
        !           176: #endif /* SIMPLE_CLOCK */
        !           177:        
        !           178:        /*
        !           179:         * Charge the time out based on the mode the cpu is in.
        !           180:         * Here again we fudge for the lack of proper interval timers
        !           181:         * assuming that the current state has been around at least
        !           182:         * one tick.
        !           183:         */
        !           184:        p = current_proc();
        !           185:        if (USERMODE(ps)) {             
        !           186:                if (p) {
        !           187:                        if (p->p_stats->p_prof.pr_scale) {
        !           188:                                p->p_flag |= P_OWEUPC;
        !           189:                                ast_on(cpu_number(), AST_UNIX);
        !           190:                        }
        !           191:                }
        !           192: 
        !           193:                /*
        !           194:                 * CPU was in user state.  Increment
        !           195:                 * user time counter, and process process-virtual time
        !           196:                 * interval timer. 
        !           197:                 */
        !           198:                if (timerisset(&p->p_stats->p_timer[ITIMER_VIRTUAL].it_value) &&
        !           199:                    itimerdecr(&p->p_stats->p_timer[ITIMER_VIRTUAL], tick) == 0)
        !           200:                        psignal(p, SIGVTALRM);
        !           201:        }
        !           202: 
        !           203:        /*
        !           204:         * If the cpu is currently scheduled to a process, then
        !           205:         * charge it with resource utilization for a tick, updating
        !           206:         * statistics which run in (user+system) virtual time,
        !           207:         * such as the cpu time limit and profiling timers.
        !           208:         * This assumes that the current process has been running
        !           209:         * the entire last tick.
        !           210:         */
        !           211:        if (p && !(thread->state & TH_IDLE))
        !           212:        {               
        !           213:                if (p->p_limit->pl_rlimit[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
        !           214:                    time_value_t        sys_time, user_time;
        !           215: 
        !           216:                    thread_read_times(thread, &user_time, &sys_time);
        !           217:                    if ((sys_time.seconds + user_time.seconds + 1) >
        !           218:                        p->p_limit->pl_rlimit[RLIMIT_CPU].rlim_cur) {
        !           219:                        psignal(p, SIGXCPU);
        !           220:                        if (p->p_limit->pl_rlimit[RLIMIT_CPU].rlim_cur <
        !           221:                            p->p_limit->pl_rlimit[RLIMIT_CPU].rlim_max)
        !           222:                                p->p_limit->pl_rlimit[RLIMIT_CPU].rlim_cur += 5;
        !           223:                        }
        !           224:                }
        !           225:                if (timerisset(&p->p_stats->p_timer[ITIMER_PROF].it_value) &&
        !           226:                    itimerdecr(&p->p_stats->p_timer[ITIMER_PROF], tick) == 0)
        !           227:                        psignal(p, SIGPROF);
        !           228:        }
        !           229: 
        !           230:        /*
        !           231:         * Increment the time-of-day, and schedule
        !           232:         * processing of the callouts at a very low cpu priority,
        !           233:         * so we don't keep the relatively high clock interrupt
        !           234:         * priority any longer than necessary.
        !           235:         */
        !           236: 
        !           237:        /*
        !           238:         * Gather the statistics.
        !           239:         */
        !           240:        gatherstats(pc, ps);
        !           241: 
        !           242: #if    NCPUS > 1
        !           243:        if (cpu_number() != master_cpu)
        !           244:                return;
        !           245: #endif /* NCPUS > 1 */
        !           246: 
        !           247:        if (timedelta != 0) {
        !           248:                register delta;
        !           249:                clock_res_t nsdelta = tickdelta * NSEC_PER_USEC;
        !           250: 
        !           251:                if (timedelta < 0) {
        !           252:                        delta = tick - tickdelta;
        !           253:                        timedelta += tickdelta;
        !           254:                        nsdelta = -nsdelta;
        !           255:                } else {
        !           256:                        delta = tick + tickdelta;
        !           257:                        timedelta -= tickdelta;
        !           258:                }
        !           259:                clock_adjust_counter(Calendar, nsdelta);
        !           260:        }
        !           261:        microtime(&time);
        !           262: }
        !           263: 
        !           264: #if    SIMPLE_CLOCK
        !           265: #undef tick
        !           266: #endif /* SIMPLE_CLOCK */
        !           267: 
        !           268: /*
        !           269:  * Gather statistics on resource utilization.
        !           270:  *
        !           271:  * We make a gross assumption: that the system has been in the
        !           272:  * state it is in (user state, kernel state, interrupt state,
        !           273:  * or idle state) for the entire last time interval, and
        !           274:  * update statistics accordingly.
        !           275:  */
        !           276: /*ARGSUSED*/
        !           277: void
        !           278: gatherstats(pc, ps)
        !           279:        caddr_t pc;
        !           280:        int ps;
        !           281: {
        !           282:        register int cpstate, s;
        !           283: 
        !           284: #ifdef GPROF
        !           285:     struct gmonparam *p = &_gmonparam;
        !           286: #endif
        !           287: 
        !           288:        /*
        !           289:         * Determine what state the cpu is in.
        !           290:         */
        !           291:        if (USERMODE(ps)) {
        !           292:                /*
        !           293:                 * CPU was in user state.
        !           294:                 */
        !           295:                if (current_proc()->p_nice > NZERO)
        !           296:                        cpstate = CP_NICE;
        !           297:                else
        !           298:                        cpstate = CP_USER;
        !           299:        } else {
        !           300:                /*
        !           301:                 * CPU was in system state.  If profiling kernel
        !           302:                 * increment a counter.  If no process is running
        !           303:                 * then this is a system tick if we were running
        !           304:                 * at a non-zero IPL (in a driver).  If a process is running,
        !           305:                 * then we charge it with system time even if we were
        !           306:                 * at a non-zero IPL, since the system often runs
        !           307:                 * this way during processing of system calls.
        !           308:                 * This is approximate, but the lack of true interval
        !           309:                 * timers makes doing anything else difficult.
        !           310:                 */
        !           311:                cpstate = CP_SYS;
        !           312:                if ((current_thread()->state & TH_IDLE) && BASEPRI(ps))
        !           313:                        cpstate = CP_IDLE;
        !           314: #ifdef GPROF
        !           315:                if (p->state == GMON_PROF_ON) {
        !           316:                        s = pc - p->lowpc;
        !           317:                        if (s < p->textsize) {
        !           318:                                s /= (HISTFRACTION * sizeof(*p->kcount));
        !           319:                                p->kcount[s]++;
        !           320:                        }
        !           321:                }
        !           322: #endif
        !           323:        }
        !           324:        /*
        !           325:         * We maintain statistics shown by user-level statistics
        !           326:         * programs:  the amount of time in each cpu state, and
        !           327:         * the amount of time each of DK_NDRIVE ``drives'' is busy.
        !           328:         */
        !           329:        cp_time[cpstate]++;
        !           330:        for (s = 0; s < DK_NDRIVE; s++)
        !           331:                if (dk_busy & (1 << s))
        !           332:                        dk_time[s]++;
        !           333: }
        !           334: 
        !           335: /*
        !           336:  * Arrange that (*fun)(arg) is called in t/hz seconds.
        !           337:  */
        !           338: void
        !           339: timeout(ftn, arg, ticks)
        !           340:        void (*ftn) __P((void *));
        !           341:        void *arg;
        !           342:        register int ticks;
        !           343: {
        !           344:        int             s;
        !           345:        tvalspec_t      deadline;
        !           346:        extern
        !           347:            tvalspec_t  tick_stamp;
        !           348: 
        !           349:        if (ticks <= 0)
        !           350:                ticks = 1;
        !           351: 
        !           352:        s = splhigh();
        !           353:        deadline = ticks_to_tvalspec(ticks);
        !           354:        ADD_TVALSPEC(&deadline, &tick_stamp);
        !           355: 
        !           356:        thread_call_func_delayed(
        !           357:                        (thread_call_func_t)ftn,
        !           358:                        (thread_call_spec_t)arg, deadline);
        !           359:        splx(s);
        !           360: }
        !           361: 
        !           362: /*
        !           363:  * untimeout is called to remove a function timeout call
        !           364:  * from the callout structure.
        !           365:  */
        !           366: int
        !           367: untimeout(ftn, arg)
        !           368:        void (*ftn) __P((void *));
        !           369:        void *arg;
        !           370: {
        !           371:        thread_call_func_cancel(
        !           372:                        (thread_call_func_t)ftn,
        !           373:                        (thread_call_spec_t)arg, FALSE);
        !           374: 
        !           375:        return TRUE;    /* XXX cheat */
        !           376: }
        !           377: 
        !           378: /*
        !           379:  * Compute number of hz until specified time.
        !           380:  * Used to compute third argument to timeout() from an
        !           381:  * absolute time.
        !           382:  */
        !           383: hzto(tv)
        !           384:        struct timeval *tv;
        !           385: {
        !           386:        register long ticks;
        !           387:        register long sec;
        !           388:        int s = splhigh();
        !           389:        
        !           390:        /*
        !           391:         * If number of milliseconds will fit in 32 bit arithmetic,
        !           392:         * then compute number of milliseconds to time and scale to
        !           393:         * ticks.  Otherwise just compute number of hz in time, rounding
        !           394:         * times greater than representible to maximum value.
        !           395:         *
        !           396:         * Delta times less than 25 days can be computed ``exactly''.
        !           397:         * Maximum value for any timeout in 10ms ticks is 250 days.
        !           398:         */
        !           399:        sec = tv->tv_sec - time.tv_sec;
        !           400:        if (sec <= 0x7fffffff / 1000 - 1000)
        !           401:                ticks = ((tv->tv_sec - time.tv_sec) * 1000 +
        !           402:                        (tv->tv_usec - time.tv_usec) / 1000)
        !           403:                                / (tick / 1000);
        !           404:        else if (sec <= 0x7fffffff / hz)
        !           405:                ticks = sec * hz;
        !           406:        else
        !           407:                ticks = 0x7fffffff;
        !           408:        splx(s);
        !           409:        return (ticks);
        !           410: }
        !           411: 
        !           412: /*
        !           413:  * Convert ticks to a timeval
        !           414:  */
        !           415: ticks_to_timeval(ticks, tvp)
        !           416:        register long ticks;
        !           417:        struct timeval *tvp;
        !           418: {
        !           419:        tvp->tv_sec = ticks/hz;
        !           420:        tvp->tv_usec = (ticks%hz) * tick;
        !           421:        ASSERT(tvp->tv_usec < 1000000);
        !           422: }
        !           423: 
        !           424: /*
        !           425:  * Return information about system clocks.
        !           426:  */
        !           427: int
        !           428: sysctl_clockrate(where, sizep)
        !           429:        register char *where;
        !           430:        size_t *sizep;
        !           431: {
        !           432:        struct clockinfo clkinfo;
        !           433: 
        !           434:        /*
        !           435:         * Construct clockinfo structure.
        !           436:         */
        !           437:        clkinfo.hz = hz;
        !           438:        clkinfo.tick = tick;
        !           439:        clkinfo.profhz = hz;
        !           440:        clkinfo.stathz = hz;
        !           441:        return (sysctl_rdstruct(where, sizep, NULL, &clkinfo, sizeof(clkinfo)));
        !           442: }
        !           443: 
        !           444: /*
        !           445:  * Start profiling on a process.
        !           446:  *
        !           447:  * Kernel profiling passes kernel_proc which never exits and hence
        !           448:  * keeps the profile clock running constantly.
        !           449:  */
        !           450: void
        !           451: startprofclock(p)
        !           452:        register struct proc *p;
        !           453: {
        !           454:        if ((p->p_flag & P_PROFIL) == 0)
        !           455:                p->p_flag |= P_PROFIL;
        !           456: }
        !           457: 
        !           458: /*
        !           459:  * Stop profiling on a process.
        !           460:  */
        !           461: void
        !           462: stopprofclock(p)
        !           463:        register struct proc *p;
        !           464: {
        !           465:        if (p->p_flag & P_PROFIL)
        !           466:                p->p_flag &= ~P_PROFIL;
        !           467: }

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