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Diffstat (limited to 'sys/kern/kern_clock.c')
| -rw-r--r-- | sys/kern/kern_clock.c | 528 |
1 files changed, 528 insertions, 0 deletions
diff --git a/sys/kern/kern_clock.c b/sys/kern/kern_clock.c new file mode 100644 index 0000000..f42900c --- /dev/null +++ b/sys/kern/kern_clock.c @@ -0,0 +1,528 @@ +/*- + * Copyright (c) 1982, 1986, 1991, 1993 + * The Regents of the University of California. All rights reserved. + * (c) UNIX System Laboratories, Inc. + * All or some portions of this file are derived from material licensed + * to the University of California by American Telephone and Telegraph + * Co. or Unix System Laboratories, Inc. and are reproduced herein with + * the permission of UNIX System Laboratories, Inc. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 + */ + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/dkstat.h> +#include <sys/callout.h> +#include <sys/kernel.h> +#include <sys/proc.h> +#include <sys/resourcevar.h> + +#include <machine/cpu.h> + +#ifdef GPROF +#include <sys/gmon.h> +#endif + +/* + * Clock handling routines. + * + * This code is written to operate with two timers that run independently of + * each other. The main clock, running hz times per second, is used to keep + * track of real time. The second timer handles kernel and user profiling, + * and does resource use estimation. If the second timer is programmable, + * it is randomized to avoid aliasing between the two clocks. For example, + * the randomization prevents an adversary from always giving up the cpu + * just before its quantum expires. Otherwise, it would never accumulate + * cpu ticks. The mean frequency of the second timer is stathz. + * + * If no second timer exists, stathz will be zero; in this case we drive + * profiling and statistics off the main clock. This WILL NOT be accurate; + * do not do it unless absolutely necessary. + * + * The statistics clock may (or may not) be run at a higher rate while + * profiling. This profile clock runs at profhz. We require that profhz + * be an integral multiple of stathz. + * + * If the statistics clock is running fast, it must be divided by the ratio + * profhz/stathz for statistics. (For profiling, every tick counts.) + */ + +/* + * TODO: + * allocate more timeout table slots when table overflows. + */ + +/* + * Bump a timeval by a small number of usec's. + */ +#define BUMPTIME(t, usec) { \ + register volatile struct timeval *tp = (t); \ + register long us; \ + \ + tp->tv_usec = us = tp->tv_usec + (usec); \ + if (us >= 1000000) { \ + tp->tv_usec = us - 1000000; \ + tp->tv_sec++; \ + } \ +} + +int stathz; +int profhz; +int profprocs; +int ticks; +static int psdiv, pscnt; /* prof => stat divider */ +int psratio; /* ratio: prof / stat */ + +volatile struct timeval time; +volatile struct timeval mono_time; + +/* + * Initialize clock frequencies and start both clocks running. + */ +void +initclocks() +{ + register int i; + + /* + * Set divisors to 1 (normal case) and let the machine-specific + * code do its bit. + */ + psdiv = pscnt = 1; + cpu_initclocks(); + + /* + * Compute profhz/stathz, and fix profhz if needed. + */ + i = stathz ? stathz : hz; + if (profhz == 0) + profhz = i; + psratio = profhz / i; +} + +/* + * The real-time timer, interrupting hz times per second. + */ +void +hardclock(frame) + register struct clockframe *frame; +{ + register struct callout *p1; + register struct proc *p; + register int delta, needsoft; + extern int tickdelta; + extern long timedelta; + + /* + * Update real-time timeout queue. + * At front of queue are some number of events which are ``due''. + * The time to these is <= 0 and if negative represents the + * number of ticks which have passed since it was supposed to happen. + * The rest of the q elements (times > 0) are events yet to happen, + * where the time for each is given as a delta from the previous. + * Decrementing just the first of these serves to decrement the time + * to all events. + */ + needsoft = 0; + for (p1 = calltodo.c_next; p1 != NULL; p1 = p1->c_next) { + if (--p1->c_time > 0) + break; + needsoft = 1; + if (p1->c_time == 0) + break; + } + + p = curproc; + if (p) { + register struct pstats *pstats; + + /* + * Run current process's virtual and profile time, as needed. + */ + pstats = p->p_stats; + if (CLKF_USERMODE(frame) && + timerisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) && + itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0) + psignal(p, SIGVTALRM); + if (timerisset(&pstats->p_timer[ITIMER_PROF].it_value) && + itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0) + psignal(p, SIGPROF); + } + + /* + * If no separate statistics clock is available, run it from here. + */ + if (stathz == 0) + statclock(frame); + + /* + * Increment the time-of-day. The increment is just ``tick'' unless + * we are still adjusting the clock; see adjtime(). + */ + ticks++; + if (timedelta == 0) + delta = tick; + else { + delta = tick + tickdelta; + timedelta -= tickdelta; + } + BUMPTIME(&time, delta); + BUMPTIME(&mono_time, delta); + + /* + * Process callouts at a very low cpu priority, so we don't keep the + * relatively high clock interrupt priority any longer than necessary. + */ + if (needsoft) { + if (CLKF_BASEPRI(frame)) { + /* + * Save the overhead of a software interrupt; + * it will happen as soon as we return, so do it now. + */ + (void)splsoftclock(); + softclock(); + } else + setsoftclock(); + } +} + +/* + * Software (low priority) clock interrupt. + * Run periodic events from timeout queue. + */ +/*ARGSUSED*/ +void +softclock() +{ + register struct callout *c; + register void *arg; + register void (*func) __P((void *)); + register int s; + + s = splhigh(); + while ((c = calltodo.c_next) != NULL && c->c_time <= 0) { + func = c->c_func; + arg = c->c_arg; + calltodo.c_next = c->c_next; + c->c_next = callfree; + callfree = c; + splx(s); + (*func)(arg); + (void) splhigh(); + } + splx(s); +} + +/* + * timeout -- + * Execute a function after a specified length of time. + * + * untimeout -- + * Cancel previous timeout function call. + * + * See AT&T BCI Driver Reference Manual for specification. This + * implementation differs from that one in that no identification + * value is returned from timeout, rather, the original arguments + * to timeout are used to identify entries for untimeout. + */ +void +timeout(ftn, arg, ticks) + void (*ftn) __P((void *)); + void *arg; + register int ticks; +{ + register struct callout *new, *p, *t; + register int s; + + if (ticks <= 0) + ticks = 1; + + /* Lock out the clock. */ + s = splhigh(); + + /* Fill in the next free callout structure. */ + if (callfree == NULL) + panic("timeout table full"); + new = callfree; + callfree = new->c_next; + new->c_arg = arg; + new->c_func = ftn; + + /* + * The time for each event is stored as a difference from the time + * of the previous event on the queue. Walk the queue, correcting + * the ticks argument for queue entries passed. Correct the ticks + * value for the queue entry immediately after the insertion point + * as well. Watch out for negative c_time values; these represent + * overdue events. + */ + for (p = &calltodo; + (t = p->c_next) != NULL && ticks > t->c_time; p = t) + if (t->c_time > 0) + ticks -= t->c_time; + new->c_time = ticks; + if (t != NULL) + t->c_time -= ticks; + + /* Insert the new entry into the queue. */ + p->c_next = new; + new->c_next = t; + splx(s); +} + +void +untimeout(ftn, arg) + void (*ftn) __P((void *)); + void *arg; +{ + register struct callout *p, *t; + register int s; + + s = splhigh(); + for (p = &calltodo; (t = p->c_next) != NULL; p = t) + if (t->c_func == ftn && t->c_arg == arg) { + /* Increment next entry's tick count. */ + if (t->c_next && t->c_time > 0) + t->c_next->c_time += t->c_time; + + /* Move entry from callout queue to callfree queue. */ + p->c_next = t->c_next; + t->c_next = callfree; + callfree = t; + break; + } + splx(s); +} + +/* + * Compute number of hz until specified time. Used to + * compute third argument to timeout() from an absolute time. + */ +int +hzto(tv) + struct timeval *tv; +{ + register long ticks, sec; + int s; + + /* + * If number of milliseconds will fit in 32 bit arithmetic, + * then compute number of milliseconds to time and scale to + * ticks. Otherwise just compute number of hz in time, rounding + * times greater than representible to maximum value. + * + * Delta times less than 25 days can be computed ``exactly''. + * Maximum value for any timeout in 10ms ticks is 250 days. + */ + s = splhigh(); + sec = tv->tv_sec - time.tv_sec; + if (sec <= 0x7fffffff / 1000 - 1000) + ticks = ((tv->tv_sec - time.tv_sec) * 1000 + + (tv->tv_usec - time.tv_usec) / 1000) / (tick / 1000); + else if (sec <= 0x7fffffff / hz) + ticks = sec * hz; + else + ticks = 0x7fffffff; + splx(s); + return (ticks); +} + +/* + * Start profiling on a process. + * + * Kernel profiling passes proc0 which never exits and hence + * keeps the profile clock running constantly. + */ +void +startprofclock(p) + register struct proc *p; +{ + int s; + + if ((p->p_flag & P_PROFIL) == 0) { + p->p_flag |= P_PROFIL; + if (++profprocs == 1 && stathz != 0) { + s = splstatclock(); + psdiv = pscnt = psratio; + setstatclockrate(profhz); + splx(s); + } + } +} + +/* + * Stop profiling on a process. + */ +void +stopprofclock(p) + register struct proc *p; +{ + int s; + + if (p->p_flag & P_PROFIL) { + p->p_flag &= ~P_PROFIL; + if (--profprocs == 0 && stathz != 0) { + s = splstatclock(); + psdiv = pscnt = 1; + setstatclockrate(stathz); + splx(s); + } + } +} + +int dk_ndrive = DK_NDRIVE; + +/* + * Statistics clock. Grab profile sample, and if divider reaches 0, + * do process and kernel statistics. + */ +void +statclock(frame) + register struct clockframe *frame; +{ +#ifdef GPROF + register struct gmonparam *g; +#endif + register struct proc *p; + register int i; + + if (CLKF_USERMODE(frame)) { + p = curproc; + if (p->p_flag & P_PROFIL) + addupc_intr(p, CLKF_PC(frame), 1); + if (--pscnt > 0) + return; + /* + * Came from user mode; CPU was in user state. + * If this process is being profiled record the tick. + */ + p->p_uticks++; + if (p->p_nice > NZERO) + cp_time[CP_NICE]++; + else + cp_time[CP_USER]++; + } else { +#ifdef GPROF + /* + * Kernel statistics are just like addupc_intr, only easier. + */ + g = &_gmonparam; + if (g->state == GMON_PROF_ON) { + i = CLKF_PC(frame) - g->lowpc; + if (i < g->textsize) { + i /= HISTFRACTION * sizeof(*g->kcount); + g->kcount[i]++; + } + } +#endif + if (--pscnt > 0) + return; + /* + * Came from kernel mode, so we were: + * - handling an interrupt, + * - doing syscall or trap work on behalf of the current + * user process, or + * - spinning in the idle loop. + * Whichever it is, charge the time as appropriate. + * Note that we charge interrupts to the current process, + * regardless of whether they are ``for'' that process, + * so that we know how much of its real time was spent + * in ``non-process'' (i.e., interrupt) work. + */ + p = curproc; + if (CLKF_INTR(frame)) { + if (p != NULL) + p->p_iticks++; + cp_time[CP_INTR]++; + } else if (p != NULL) { + p->p_sticks++; + cp_time[CP_SYS]++; + } else + cp_time[CP_IDLE]++; + } + pscnt = psdiv; + + /* + * We maintain statistics shown by user-level statistics + * programs: the amount of time in each cpu state, and + * the amount of time each of DK_NDRIVE ``drives'' is busy. + * + * XXX should either run linked list of drives, or (better) + * grab timestamps in the start & done code. + */ + for (i = 0; i < DK_NDRIVE; i++) + if (dk_busy & (1 << i)) + dk_time[i]++; + + /* + * We adjust the priority of the current process. The priority of + * a process gets worse as it accumulates CPU time. The cpu usage + * estimator (p_estcpu) is increased here. The formula for computing + * priorities (in kern_synch.c) will compute a different value each + * time p_estcpu increases by 4. The cpu usage estimator ramps up + * quite quickly when the process is running (linearly), and decays + * away exponentially, at a rate which is proportionally slower when + * the system is busy. The basic principal is that the system will + * 90% forget that the process used a lot of CPU time in 5 * loadav + * seconds. This causes the system to favor processes which haven't + * run much recently, and to round-robin among other processes. + */ + if (p != NULL) { + p->p_cpticks++; + if (++p->p_estcpu == 0) + p->p_estcpu--; + if ((p->p_estcpu & 3) == 0) { + resetpriority(p); + if (p->p_priority >= PUSER) + p->p_priority = p->p_usrpri; + } + } +} + +/* + * Return information about system clocks. + */ +sysctl_clockrate(where, sizep) + register char *where; + size_t *sizep; +{ + struct clockinfo clkinfo; + + /* + * Construct clockinfo structure. + */ + clkinfo.hz = hz; + clkinfo.tick = tick; + clkinfo.profhz = profhz; + clkinfo.stathz = stathz ? stathz : hz; + return (sysctl_rdstruct(where, sizep, NULL, &clkinfo, sizeof(clkinfo))); +} |
