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IABSD.fr/src/sys/kern/kern_clock.c
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/* $OpenBSD: kern_clock.c,v 1.127 2025/06/01 03:43:48 dlg 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 <sys/param.h> #include <sys/systm.h> #include <sys/clockintr.h> #include <sys/timeout.h> #include <sys/kernel.h> #include <sys/limits.h> #include <sys/proc.h> #include <sys/user.h> #include <sys/resourcevar.h> #include <sys/sysctl.h> #include <sys/sched.h> #include <sys/timetc.h> #include <uvm/uvm_extern.h> /* * 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.) */ int stathz; int profhz; int profprocs; int ticks = INT_MAX - (15 * 60 * HZ); /* Don't force early wrap around, triggers bug in inteldrm */ volatile unsigned long jiffies; uint64_t hardclock_period; /* [I] hardclock period (ns) */ uint64_t statclock_avg; /* [I] average statclock period (ns) */ uint64_t statclock_min; /* [I] minimum statclock period (ns) */ uint32_t statclock_mask; /* [I] set of allowed offsets */ int statclock_is_randomized; /* [I] fixed or pseudorandom period? */ /* * Initialize clock frequencies and start both clocks running. */ void initclocks(void) { uint64_t half_avg; uint32_t var; /* * Let the machine-specific code do its bit. */ cpu_initclocks(); KASSERT(hz > 0 && hz <= 1000000000); hardclock_period = 1000000000 / hz; roundrobin_period = hardclock_period * 10; KASSERT(stathz >= 1 && stathz <= 1000000000); /* * Compute the average statclock() period. Then find var, the * largest 32-bit power of two such that var <= statclock_avg / 2. */ statclock_avg = 1000000000 / stathz; half_avg = statclock_avg / 2; for (var = 1U << 31; var > half_avg; var /= 2) continue; /* * Set a lower bound for the range using statclock_avg and var. * The mask for that range is just (var - 1). */ statclock_min = statclock_avg - (var / 2); statclock_mask = var - 1; KASSERT(profhz >= stathz && profhz <= 1000000000); KASSERT(profhz % stathz == 0); profclock_period = 1000000000 / profhz; inittimecounter(); /* Start dispatching clock interrupts on the primary CPU. */ cpu_startclock(); } /* * The real-time timer, interrupting hz times per second. */ void hardclock(struct clockframe *frame) { tc_ticktock(); ticks++; jiffies++; /* * Update the timeout wheel. */ timeout_hardclock_update(); } /* * Compute number of hz in the specified amount of time. */ int tvtohz(const struct timeval *tv) { unsigned long nticks; time_t sec; long 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)) nticks = 0; else if (sec <= LONG_MAX / 1000000) nticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) / tick + 1; else if (sec <= LONG_MAX / hz) nticks = sec * hz + ((unsigned long)usec + (tick - 1)) / tick + 1; else nticks = LONG_MAX; if (nticks > INT_MAX) nticks = INT_MAX; return ((int)nticks); } int tstohz(const struct timespec *ts) { struct timeval tv; TIMESPEC_TO_TIMEVAL(&tv, ts); /* Round up. */ if ((ts->tv_nsec % 1000) != 0) { tv.tv_usec += 1; if (tv.tv_usec >= 1000000) { tv.tv_usec -= 1000000; tv.tv_sec += 1; } } return (tvtohz(&tv)); } /* * 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) { s = splstatclock(); 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) { s = splstatclock(); setstatclockrate(stathz); splx(s); } } } /* * Statistics clock. Grab profile sample, and if divider reaches 0, * do process and kernel statistics. */ void statclock(struct clockrequest *cr, void *cf, void *arg) { uint64_t count, i; struct clockframe *frame = cf; struct cpu_info *ci = curcpu(); struct schedstate_percpu *spc = &ci->ci_schedstate; struct proc *p = curproc; struct process *pr; int tu_tick = -1; int cp_time; unsigned int gen; if (statclock_is_randomized) { count = clockrequest_advance_random(cr, statclock_min, statclock_mask); } else { count = clockrequest_advance(cr, statclock_avg); } if (CLKF_USERMODE(frame)) { pr = p->p_p; /* * Came from user mode; CPU was in user state. * If this process is being profiled record the tick. */ tu_tick = TU_UTICKS; cp_time = (pr->ps_nice > NZERO) ? CP_NICE : CP_USER; } else { /* * Came from kernel mode, so we were: * - spinning on a lock * - 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)) { tu_tick = TU_ITICKS; cp_time = CP_INTR; } else if (p != NULL && p != spc->spc_idleproc) { tu_tick = TU_STICKS; cp_time = CP_SYS; } else cp_time = CP_IDLE; if (spc->spc_spinning) cp_time = CP_SPIN; } gen = pc_sprod_enter(&spc->spc_cp_time_lock); spc->spc_cp_time[cp_time] += count; pc_sprod_leave(&spc->spc_cp_time_lock, gen); if (p != NULL) { p->p_cpticks += count; if (!ISSET(p->p_flag, P_SYSTEM) && tu_tick != -1) { struct vmspace *vm = p->p_vmspace; struct tusage *tu = &p->p_tu; gen = tu_enter(tu); tu->tu_ticks[tu_tick] += count; /* maxrss is handled by uvm */ if (tu_tick != TU_ITICKS) { tu->tu_ixrss += (vm->vm_tsize << (PAGE_SHIFT - 10)) * count; tu->tu_idrss += (vm->vm_dused << (PAGE_SHIFT - 10)) * count; tu->tu_isrss += (vm->vm_ssize << (PAGE_SHIFT - 10)) * count; } tu_leave(tu, gen); } /* * schedclock() runs every fourth statclock(). */ for (i = 0; i < count; i++) { if ((++spc->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. */ memset(&clkinfo, 0, sizeof clkinfo); clkinfo.tick = tick; clkinfo.hz = hz; clkinfo.profhz = profhz; clkinfo.stathz = stathz; return (sysctl_rdstruct(where, sizep, newp, &clkinfo, sizeof(clkinfo))); }