/* $OpenBSD: kern_clock.c,v 1.76 2012/11/05 19:39:34 miod Exp $ */ /* $NetBSD: kern_clock.c,v 1.34 1996/06/09 04:51:03 briggs Exp $ */ /*- * 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. 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef GPROF #include #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.) */ /* * Bump a timeval by a small number of usec's. */ #define BUMPTIME(t, usec) { \ volatile struct timeval *tp = (t); \ long us; \ \ tp->tv_usec = us = tp->tv_usec + (usec); \ if (us >= 1000000) { \ tp->tv_usec = us - 1000000; \ tp->tv_sec++; \ } \ } int stathz; int schedhz; int profhz; int profprocs; int ticks; static int psdiv, pscnt; /* prof => stat divider */ int psratio; /* ratio: prof / stat */ long cp_time[CPUSTATES]; void *softclock_si; /* * Initialize clock frequencies and start both clocks running. */ void initclocks(void) { int i; softclock_si = softintr_establish(IPL_SOFTCLOCK, softclock, NULL); if (softclock_si == NULL) panic("initclocks: unable to register softclock intr"); /* * 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; /* For very large HZ, ensure that division by 0 does not occur later */ if (tickadj == 0) tickadj = 1; inittimecounter(); } /* * hardclock does the accounting needed for ITIMER_PROF and ITIMER_VIRTUAL. * We don't want to send signals with psignal from hardclock because it makes * MULTIPROCESSOR locking very complicated. Instead we use a small trick * to send the signals safely and without blocking too many interrupts * while doing that (signal handling can be heavy). * * hardclock detects that the itimer has expired, and schedules a timeout * to deliver the signal. This works because of the following reasons: * - The timeout can be scheduled with a 1 tick time because we're * doing it before the timeout processing in hardclock. So it will * be scheduled to run as soon as possible. * - The timeout will be run in softclock which will run before we * return to userland and process pending signals. * - If the system is so busy that several VIRTUAL/PROF ticks are * sent before softclock processing, we'll send only one signal. * But if we'd send the signal from hardclock only one signal would * be delivered to the user process. So userland will only see one * signal anyway. */ void virttimer_trampoline(void *v) { struct process *pr = v; psignal(pr->ps_mainproc, SIGVTALRM); } void proftimer_trampoline(void *v) { struct process *pr = v; psignal(pr->ps_mainproc, SIGPROF); } /* * The real-time timer, interrupting hz times per second. */ void hardclock(struct clockframe *frame) { struct proc *p; struct cpu_info *ci = curcpu(); p = curproc; if (p && ((p->p_flag & (P_SYSTEM | P_WEXIT)) == 0)) { struct process *pr = p->p_p; /* * Run current process's virtual and profile time, as needed. */ if (CLKF_USERMODE(frame) && timerisset(&pr->ps_timer[ITIMER_VIRTUAL].it_value) && itimerdecr(&pr->ps_timer[ITIMER_VIRTUAL], tick) == 0) timeout_add(&pr->ps_virt_to, 1); if (timerisset(&pr->ps_timer[ITIMER_PROF].it_value) && itimerdecr(&pr->ps_timer[ITIMER_PROF], tick) == 0) timeout_add(&pr->ps_prof_to, 1); } /* * If no separate statistics clock is available, run it from here. */ if (stathz == 0) statclock(frame); if (--ci->ci_schedstate.spc_rrticks <= 0) roundrobin(ci); /* * If we are not the primary CPU, we're not allowed to do * any more work. */ if (CPU_IS_PRIMARY(ci) == 0) return; tc_ticktock(); /* * Update real-time timeout queue. * Process callouts at a very low cpu priority, so we don't keep the * relatively high clock interrupt priority any longer than necessary. */ if (timeout_hardclock_update()) softintr_schedule(softclock_si); } /* * Compute number of hz until specified time. Used to * compute the second argument to timeout_add() from an absolute time. */ int hzto(const struct timeval *tv) { struct timeval now; unsigned long ticks; long sec, usec; /* * If the number of usecs in the whole seconds part of the time * difference fits in a long, then the total number of usecs will * fit in an unsigned long. Compute the total and convert it to * ticks, rounding up and adding 1 to allow for the current tick * to expire. Rounding also depends on unsigned long arithmetic * to avoid overflow. * * Otherwise, if the number of ticks in the whole seconds part of * the time difference fits in a long, then convert the parts to * ticks separately and add, using similar rounding methods and * overflow avoidance. This method would work in the previous * case but it is slightly slower and assumes that hz is integral. * * Otherwise, round the time difference down to the maximum * representable value. * * If ints have 32 bits, then the maximum value for any timeout in * 10ms ticks is 248 days. */ getmicrotime(&now); sec = tv->tv_sec - now.tv_sec; usec = tv->tv_usec - now.tv_usec; if (usec < 0) { sec--; usec += 1000000; } if (sec < 0 || (sec == 0 && usec <= 0)) { ticks = 0; } else if (sec <= LONG_MAX / 1000000) ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) / tick + 1; else if (sec <= LONG_MAX / hz) ticks = sec * hz + ((unsigned long)usec + (tick - 1)) / tick + 1; else ticks = LONG_MAX; if (ticks > INT_MAX) ticks = INT_MAX; return ((int)ticks); } /* * Compute number of hz in the specified amount of time. */ int tvtohz(const struct timeval *tv) { unsigned long ticks; long sec, usec; /* * If the number of usecs in the whole seconds part of the time * fits in a long, then the total number of usecs will * fit in an unsigned long. Compute the total and convert it to * ticks, rounding up and adding 1 to allow for the current tick * to expire. Rounding also depends on unsigned long arithmetic * to avoid overflow. * * Otherwise, if the number of ticks in the whole seconds part of * the time fits in a long, then convert the parts to * ticks separately and add, using similar rounding methods and * overflow avoidance. This method would work in the previous * case but it is slightly slower and assumes that hz is integral. * * Otherwise, round the time down to the maximum * representable value. * * If ints have 32 bits, then the maximum value for any timeout in * 10ms ticks is 248 days. */ sec = tv->tv_sec; usec = tv->tv_usec; if (sec < 0 || (sec == 0 && usec <= 0)) ticks = 0; else if (sec <= LONG_MAX / 1000000) ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) / tick + 1; else if (sec <= LONG_MAX / hz) ticks = sec * hz + ((unsigned long)usec + (tick - 1)) / tick + 1; else ticks = LONG_MAX; if (ticks > INT_MAX) ticks = INT_MAX; return ((int)ticks); } /* * Start profiling on a process. * * Kernel profiling passes proc0 which never exits and hence * keeps the profile clock running constantly. */ void startprofclock(struct process *pr) { int s; if ((pr->ps_flags & PS_PROFIL) == 0) { atomic_setbits_int(&pr->ps_flags, PS_PROFIL); if (++profprocs == 1 && stathz != 0) { s = splstatclock(); psdiv = pscnt = psratio; setstatclockrate(profhz); splx(s); } } } /* * Stop profiling on a process. */ void stopprofclock(struct process *pr) { int s; if (pr->ps_flags & PS_PROFIL) { atomic_clearbits_int(&pr->ps_flags, PS_PROFIL); if (--profprocs == 0 && stathz != 0) { s = splstatclock(); psdiv = pscnt = 1; setstatclockrate(stathz); splx(s); } } } /* * Statistics clock. Grab profile sample, and if divider reaches 0, * do process and kernel statistics. */ void statclock(struct clockframe *frame) { #ifdef GPROF struct gmonparam *g; u_long i; #endif struct cpu_info *ci = curcpu(); struct schedstate_percpu *spc = &ci->ci_schedstate; struct proc *p = curproc; struct process *pr; /* * Notice changes in divisor frequency, and adjust clock * frequency accordingly. */ if (spc->spc_psdiv != psdiv) { spc->spc_psdiv = psdiv; spc->spc_pscnt = psdiv; if (psdiv == 1) { setstatclockrate(stathz); } else { setstatclockrate(profhz); } } if (CLKF_USERMODE(frame)) { pr = p->p_p; if (pr->ps_flags & PS_PROFIL) addupc_intr(p, CLKF_PC(frame)); if (--spc->spc_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 (pr->ps_nice > NZERO) spc->spc_cp_time[CP_NICE]++; else spc->spc_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 defined(PROC_PC) if (p != NULL && p->p_p->ps_flags & PS_PROFIL) addupc_intr(p, PROC_PC(p)); #endif if (--spc->spc_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. */ if (CLKF_INTR(frame)) { if (p != NULL) p->p_iticks++; spc->spc_cp_time[CP_INTR]++; } else if (p != NULL && p != spc->spc_idleproc) { p->p_sticks++; spc->spc_cp_time[CP_SYS]++; } else spc->spc_cp_time[CP_IDLE]++; } spc->spc_pscnt = psdiv; if (p != NULL) { p->p_cpticks++; /* * If no schedclock is provided, call it here at ~~12-25 Hz; * ~~16 Hz is best */ if (schedhz == 0) { if ((++curcpu()->ci_schedstate.spc_schedticks & 3) == 0) schedclock(p); } } } /* * Return information about system clocks. */ int sysctl_clockrate(char *where, size_t *sizep, void *newp) { struct clockinfo clkinfo; /* * Construct clockinfo structure. */ clkinfo.tick = tick; clkinfo.tickadj = tickadj; clkinfo.hz = hz; clkinfo.profhz = profhz; clkinfo.stathz = stathz ? stathz : hz; return (sysctl_rdstruct(where, sizep, newp, &clkinfo, sizeof(clkinfo))); }