/*- * Copyright (c) 1982, 1986, 1990, 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_synch.c 8.9 (Berkeley) 5/19/95 * $FreeBSD$ */ #include "opt_ktrace.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef KTRACE #include #include #endif #include static void sched_setup __P((void *dummy)); SYSINIT(sched_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, sched_setup, NULL) int hogticks; int lbolt; int sched_quantum; /* Roundrobin scheduling quantum in ticks. */ static struct callout schedcpu_callout; static struct callout roundrobin_callout; static void endtsleep __P((void *)); static void roundrobin __P((void *arg)); static void schedcpu __P((void *arg)); static int sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) { int error, new_val; new_val = sched_quantum * tick; error = sysctl_handle_int(oidp, &new_val, 0, req); if (error != 0 || req->newptr == NULL) return (error); if (new_val < tick) return (EINVAL); sched_quantum = new_val / tick; hogticks = 2 * sched_quantum; return (0); } SYSCTL_PROC(_kern, OID_AUTO, quantum, CTLTYPE_INT|CTLFLAG_RW, 0, sizeof sched_quantum, sysctl_kern_quantum, "I", ""); /* * Arrange to reschedule if necessary, taking the priorities and * schedulers into account. */ void maybe_resched(p) struct proc *p; { mtx_assert(&sched_lock, MA_OWNED); if (p->p_pri.pri_level < curproc->p_pri.pri_level) need_resched(curproc); } int roundrobin_interval(void) { return (sched_quantum); } /* * Force switch among equal priority processes every 100ms. */ /* ARGSUSED */ static void roundrobin(arg) void *arg; { mtx_lock_spin(&sched_lock); need_resched(curproc); #ifdef SMP forward_roundrobin(); #endif mtx_unlock_spin(&sched_lock); callout_reset(&roundrobin_callout, sched_quantum, roundrobin, NULL); } /* * Constants for digital decay and forget: * 90% of (p_estcpu) usage in 5 * loadav time * 95% of (p_pctcpu) usage in 60 seconds (load insensitive) * Note that, as ps(1) mentions, this can let percentages * total over 100% (I've seen 137.9% for 3 processes). * * Note that schedclock() updates p_estcpu and p_cpticks asynchronously. * * We wish to decay away 90% of p_estcpu in (5 * loadavg) seconds. * That is, the system wants to compute a value of decay such * that the following for loop: * for (i = 0; i < (5 * loadavg); i++) * p_estcpu *= decay; * will compute * p_estcpu *= 0.1; * for all values of loadavg: * * Mathematically this loop can be expressed by saying: * decay ** (5 * loadavg) ~= .1 * * The system computes decay as: * decay = (2 * loadavg) / (2 * loadavg + 1) * * We wish to prove that the system's computation of decay * will always fulfill the equation: * decay ** (5 * loadavg) ~= .1 * * If we compute b as: * b = 2 * loadavg * then * decay = b / (b + 1) * * We now need to prove two things: * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) * * Facts: * For x close to zero, exp(x) =~ 1 + x, since * exp(x) = 0! + x**1/1! + x**2/2! + ... . * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. * For x close to zero, ln(1+x) =~ x, since * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). * ln(.1) =~ -2.30 * * Proof of (1): * Solve (factor)**(power) =~ .1 given power (5*loadav): * solving for factor, * ln(factor) =~ (-2.30/5*loadav), or * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED * * Proof of (2): * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): * solving for power, * power*ln(b/(b+1)) =~ -2.30, or * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED * * Actual power values for the implemented algorithm are as follows: * loadav: 1 2 3 4 * power: 5.68 10.32 14.94 19.55 */ /* calculations for digital decay to forget 90% of usage in 5*loadav sec */ #define loadfactor(loadav) (2 * (loadav)) #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) /* decay 95% of `p_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); /* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */ static int fscale __unused = FSCALE; SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, ""); /* * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). * * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). * * If you don't want to bother with the faster/more-accurate formula, you * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate * (more general) method of calculating the %age of CPU used by a process. */ #define CCPU_SHIFT 11 /* * Recompute process priorities, every hz ticks. * MP-safe, called without the Giant mutex. */ /* ARGSUSED */ static void schedcpu(arg) void *arg; { register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); register struct proc *p; register int realstathz, s; realstathz = stathz ? stathz : hz; sx_slock(&allproc_lock); LIST_FOREACH(p, &allproc, p_list) { /* * Increment time in/out of memory and sleep time * (if sleeping). We ignore overflow; with 16-bit int's * (remember them?) overflow takes 45 days. if (p->p_stat == SWAIT) continue; */ mtx_lock_spin(&sched_lock); p->p_swtime++; if (p->p_stat == SSLEEP || p->p_stat == SSTOP) p->p_slptime++; p->p_pctcpu = (p->p_pctcpu * ccpu) >> FSHIFT; /* * If the process has slept the entire second, * stop recalculating its priority until it wakes up. */ if (p->p_slptime > 1) { mtx_unlock_spin(&sched_lock); continue; } /* * prevent state changes and protect run queue */ s = splhigh(); /* * p_pctcpu is only for ps. */ #if (FSHIFT >= CCPU_SHIFT) p->p_pctcpu += (realstathz == 100)? ((fixpt_t) p->p_cpticks) << (FSHIFT - CCPU_SHIFT): 100 * (((fixpt_t) p->p_cpticks) << (FSHIFT - CCPU_SHIFT)) / realstathz; #else p->p_pctcpu += ((FSCALE - ccpu) * (p->p_cpticks * FSCALE / realstathz)) >> FSHIFT; #endif p->p_cpticks = 0; p->p_estcpu = decay_cpu(loadfac, p->p_estcpu); resetpriority(p); if (p->p_pri.pri_level >= PUSER) { if ((p != curproc) && #ifdef SMP p->p_oncpu == NOCPU && /* idle */ #endif p->p_stat == SRUN && (p->p_sflag & PS_INMEM) && (p->p_pri.pri_level / RQ_PPQ) != (p->p_pri.pri_user / RQ_PPQ)) { remrunqueue(p); p->p_pri.pri_level = p->p_pri.pri_user; setrunqueue(p); } else p->p_pri.pri_level = p->p_pri.pri_user; } mtx_unlock_spin(&sched_lock); splx(s); } sx_sunlock(&allproc_lock); vmmeter(); wakeup((caddr_t)&lbolt); callout_reset(&schedcpu_callout, hz, schedcpu, NULL); } /* * Recalculate the priority of a process after it has slept for a while. * For all load averages >= 1 and max p_estcpu of 255, sleeping for at * least six times the loadfactor will decay p_estcpu to zero. */ void updatepri(p) register struct proc *p; { register unsigned int newcpu = p->p_estcpu; register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); if (p->p_slptime > 5 * loadfac) p->p_estcpu = 0; else { p->p_slptime--; /* the first time was done in schedcpu */ while (newcpu && --p->p_slptime) newcpu = decay_cpu(loadfac, newcpu); p->p_estcpu = newcpu; } resetpriority(p); } /* * We're only looking at 7 bits of the address; everything is * aligned to 4, lots of things are aligned to greater powers * of 2. Shift right by 8, i.e. drop the bottom 256 worth. */ #define TABLESIZE 128 static TAILQ_HEAD(slpquehead, proc) slpque[TABLESIZE]; #define LOOKUP(x) (((intptr_t)(x) >> 8) & (TABLESIZE - 1)) void sleepinit(void) { int i; sched_quantum = hz/10; hogticks = 2 * sched_quantum; for (i = 0; i < TABLESIZE; i++) TAILQ_INIT(&slpque[i]); } /* * General sleep call. Suspends the current process until a wakeup is * performed on the specified identifier. The process will then be made * runnable with the specified priority. Sleeps at most timo/hz seconds * (0 means no timeout). If pri includes PCATCH flag, signals are checked * before and after sleeping, else signals are not checked. Returns 0 if * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a * signal needs to be delivered, ERESTART is returned if the current system * call should be restarted if possible, and EINTR is returned if the system * call should be interrupted by the signal (return EINTR). * * The mutex argument is exited before the caller is suspended, and * entered before msleep returns. If priority includes the PDROP * flag the mutex is not entered before returning. */ int msleep(ident, mtx, priority, wmesg, timo) void *ident; struct mtx *mtx; int priority, timo; const char *wmesg; { struct proc *p = curproc; int sig, catch = priority & PCATCH; int rval = 0; WITNESS_SAVE_DECL(mtx); #ifdef KTRACE if (p && KTRPOINT(p, KTR_CSW)) ktrcsw(p->p_tracep, 1, 0); #endif WITNESS_SLEEP(0, &mtx->mtx_object); KASSERT(timo != 0 || mtx_owned(&Giant) || mtx != NULL, ("sleeping without a mutex")); mtx_lock_spin(&sched_lock); if (cold || panicstr) { /* * After a panic, or during autoconfiguration, * just give interrupts a chance, then just return; * don't run any other procs or panic below, * in case this is the idle process and already asleep. */ if (mtx != NULL && priority & PDROP) mtx_unlock_flags(mtx, MTX_NOSWITCH); mtx_unlock_spin(&sched_lock); return (0); } DROP_GIANT_NOSWITCH(); if (mtx != NULL) { mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); WITNESS_SAVE(&mtx->mtx_object, mtx); mtx_unlock_flags(mtx, MTX_NOSWITCH); if (priority & PDROP) mtx = NULL; } KASSERT(p != NULL, ("msleep1")); KASSERT(ident != NULL && p->p_stat == SRUN, ("msleep")); /* * Process may be sitting on a slpque if asleep() was called, remove * it before re-adding. */ if (p->p_wchan != NULL) unsleep(p); p->p_wchan = ident; p->p_wmesg = wmesg; p->p_slptime = 0; p->p_pri.pri_level = priority & PRIMASK; CTR3(KTR_PROC, "msleep: proc %p (pid %d, %s)", p, p->p_pid, p->p_comm); TAILQ_INSERT_TAIL(&slpque[LOOKUP(ident)], p, p_slpq); if (timo) callout_reset(&p->p_slpcallout, timo, endtsleep, p); /* * We put ourselves on the sleep queue and start our timeout * before calling CURSIG, as we could stop there, and a wakeup * or a SIGCONT (or both) could occur while we were stopped. * A SIGCONT would cause us to be marked as SSLEEP * without resuming us, thus we must be ready for sleep * when CURSIG is called. If the wakeup happens while we're * stopped, p->p_wchan will be 0 upon return from CURSIG. */ if (catch) { CTR3(KTR_PROC, "msleep caught: proc %p (pid %d, %s)", p, p->p_pid, p->p_comm); p->p_sflag |= PS_SINTR; mtx_unlock_spin(&sched_lock); PROC_LOCK(p); sig = CURSIG(p); mtx_lock_spin(&sched_lock); PROC_UNLOCK_NOSWITCH(p); if (sig != 0) { if (p->p_wchan) unsleep(p); } else if (p->p_wchan == NULL) catch = 0; } else sig = 0; if (p->p_wchan != NULL) { p->p_stat = SSLEEP; p->p_stats->p_ru.ru_nvcsw++; mi_switch(); } CTR3(KTR_PROC, "msleep resume: proc %p (pid %d, %s)", p, p->p_pid, p->p_comm); KASSERT(p->p_stat == SRUN, ("running but not SRUN")); p->p_sflag &= ~PS_SINTR; if (p->p_sflag & PS_TIMEOUT) { p->p_sflag &= ~PS_TIMEOUT; if (sig == 0) rval = EWOULDBLOCK; } else if (timo) callout_stop(&p->p_slpcallout); mtx_unlock_spin(&sched_lock); if (rval == 0 && catch) { PROC_LOCK(p); /* XXX: shouldn't we always be calling CURSIG() */ if (sig != 0 || (sig = CURSIG(p))) { if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) rval = EINTR; else rval = ERESTART; } PROC_UNLOCK(p); } PICKUP_GIANT(); #ifdef KTRACE mtx_lock(&Giant); if (KTRPOINT(p, KTR_CSW)) ktrcsw(p->p_tracep, 0, 0); mtx_unlock(&Giant); #endif if (mtx != NULL) { mtx_lock(mtx); WITNESS_RESTORE(&mtx->mtx_object, mtx); } return (rval); } /* * asleep() - async sleep call. Place process on wait queue and return * immediately without blocking. The process stays runnable until mawait() * is called. If ident is NULL, remove process from wait queue if it is still * on one. * * Only the most recent sleep condition is effective when making successive * calls to asleep() or when calling msleep(). * * The timeout, if any, is not initiated until mawait() is called. The sleep * priority, signal, and timeout is specified in the asleep() call but may be * overriden in the mawait() call. * * <<<<<<<< EXPERIMENTAL, UNTESTED >>>>>>>>>> */ int asleep(void *ident, int priority, const char *wmesg, int timo) { struct proc *p = curproc; /* * Remove preexisting wait condition (if any) and place process * on appropriate slpque, but do not put process to sleep. */ mtx_lock_spin(&sched_lock); if (p->p_wchan != NULL) unsleep(p); if (ident) { p->p_wchan = ident; p->p_wmesg = wmesg; p->p_slptime = 0; p->p_asleep.as_priority = priority; p->p_asleep.as_timo = timo; TAILQ_INSERT_TAIL(&slpque[LOOKUP(ident)], p, p_slpq); } mtx_unlock_spin(&sched_lock); return(0); } /* * mawait() - wait for async condition to occur. The process blocks until * wakeup() is called on the most recent asleep() address. If wakeup is called * prior to mawait(), mawait() winds up being a NOP. * * If mawait() is called more then once (without an intervening asleep() call), * mawait() is still effectively a NOP but it calls mi_switch() to give other * processes some cpu before returning. The process is left runnable. * * <<<<<<<< EXPERIMENTAL, UNTESTED >>>>>>>>>> */ int mawait(struct mtx *mtx, int priority, int timo) { struct proc *p = curproc; int rval = 0; WITNESS_SAVE_DECL(mtx); WITNESS_SLEEP(0, &mtx->mtx_object); KASSERT(timo > 0 || mtx_owned(&Giant) || mtx != NULL, ("sleeping without a mutex")); mtx_lock_spin(&sched_lock); DROP_GIANT_NOSWITCH(); if (mtx != NULL) { mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); WITNESS_SAVE(&mtx->mtx_object, mtx); mtx_unlock_flags(mtx, MTX_NOSWITCH); if (priority & PDROP) mtx = NULL; } if (p->p_wchan != NULL) { int sig; int catch; #ifdef KTRACE if (p && KTRPOINT(p, KTR_CSW)) ktrcsw(p->p_tracep, 1, 0); #endif /* * The call to mawait() can override defaults specified in * the original asleep(). */ if (priority < 0) priority = p->p_asleep.as_priority; if (timo < 0) timo = p->p_asleep.as_timo; /* * Install timeout */ if (timo) callout_reset(&p->p_slpcallout, timo, endtsleep, p); sig = 0; catch = priority & PCATCH; if (catch) { p->p_sflag |= PS_SINTR; mtx_unlock_spin(&sched_lock); PROC_LOCK(p); sig = CURSIG(p); mtx_lock_spin(&sched_lock); PROC_UNLOCK_NOSWITCH(p); if (sig != 0) { if (p->p_wchan) unsleep(p); } else if (p->p_wchan == NULL) catch = 0; } if (p->p_wchan != NULL) { p->p_stat = SSLEEP; p->p_stats->p_ru.ru_nvcsw++; mi_switch(); } KASSERT(p->p_stat == SRUN, ("running but not SRUN")); p->p_sflag &= ~PS_SINTR; if (p->p_sflag & PS_TIMEOUT) { p->p_sflag &= ~PS_TIMEOUT; if (sig == 0) rval = EWOULDBLOCK; } else if (timo) callout_stop(&p->p_slpcallout); mtx_unlock_spin(&sched_lock); if (rval == 0 && catch) { PROC_LOCK(p); if (sig != 0 || (sig = CURSIG(p))) { if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) rval = EINTR; else rval = ERESTART; } PROC_UNLOCK(p); } #ifdef KTRACE mtx_lock(&Giant); if (KTRPOINT(p, KTR_CSW)) ktrcsw(p->p_tracep, 0, 0); mtx_unlock(&Giant); #endif } else { /* * If as_priority is 0, mawait() has been called without an * intervening asleep(). We are still effectively a NOP, * but we call mi_switch() for safety. */ if (p->p_asleep.as_priority == 0) { p->p_stats->p_ru.ru_nvcsw++; mi_switch(); } mtx_unlock_spin(&sched_lock); } /* * clear p_asleep.as_priority as an indication that mawait() has been * called. If mawait() is called again without an intervening asleep(), * mawait() is still effectively a NOP but the above mi_switch() code * is triggered as a safety. */ if (rval == 0) p->p_asleep.as_priority = 0; PICKUP_GIANT(); if (mtx != NULL) { mtx_lock(mtx); WITNESS_RESTORE(&mtx->mtx_object, mtx); } return (rval); } /* * Implement timeout for msleep or asleep()/mawait() * * If process hasn't been awakened (wchan non-zero), * set timeout flag and undo the sleep. If proc * is stopped, just unsleep so it will remain stopped. * MP-safe, called without the Giant mutex. */ static void endtsleep(arg) void *arg; { register struct proc *p; int s; p = (struct proc *)arg; CTR3(KTR_PROC, "endtsleep: proc %p (pid %d, %s)", p, p->p_pid, p->p_comm); s = splhigh(); mtx_lock_spin(&sched_lock); if (p->p_wchan) { if (p->p_stat == SSLEEP) setrunnable(p); else unsleep(p); p->p_sflag |= PS_TIMEOUT; } mtx_unlock_spin(&sched_lock); splx(s); } /* * Remove a process from its wait queue */ void unsleep(p) register struct proc *p; { int s; s = splhigh(); mtx_lock_spin(&sched_lock); if (p->p_wchan) { TAILQ_REMOVE(&slpque[LOOKUP(p->p_wchan)], p, p_slpq); p->p_wchan = NULL; } mtx_unlock_spin(&sched_lock); splx(s); } /* * Make all processes sleeping on the specified identifier runnable. */ void wakeup(ident) register void *ident; { register struct slpquehead *qp; register struct proc *p; int s; s = splhigh(); mtx_lock_spin(&sched_lock); qp = &slpque[LOOKUP(ident)]; restart: TAILQ_FOREACH(p, qp, p_slpq) { if (p->p_wchan == ident) { TAILQ_REMOVE(qp, p, p_slpq); p->p_wchan = NULL; if (p->p_stat == SSLEEP) { /* OPTIMIZED EXPANSION OF setrunnable(p); */ CTR3(KTR_PROC, "wakeup: proc %p (pid %d, %s)", p, p->p_pid, p->p_comm); if (p->p_slptime > 1) updatepri(p); p->p_slptime = 0; p->p_stat = SRUN; if (p->p_sflag & PS_INMEM) { setrunqueue(p); maybe_resched(p); } else { p->p_sflag |= PS_SWAPINREQ; wakeup((caddr_t)&proc0); } /* END INLINE EXPANSION */ goto restart; } } } mtx_unlock_spin(&sched_lock); splx(s); } /* * Make a process sleeping on the specified identifier runnable. * May wake more than one process if a target process is currently * swapped out. */ void wakeup_one(ident) register void *ident; { register struct slpquehead *qp; register struct proc *p; int s; s = splhigh(); mtx_lock_spin(&sched_lock); qp = &slpque[LOOKUP(ident)]; TAILQ_FOREACH(p, qp, p_slpq) { if (p->p_wchan == ident) { TAILQ_REMOVE(qp, p, p_slpq); p->p_wchan = NULL; if (p->p_stat == SSLEEP) { /* OPTIMIZED EXPANSION OF setrunnable(p); */ CTR3(KTR_PROC, "wakeup1: proc %p (pid %d, %s)", p, p->p_pid, p->p_comm); if (p->p_slptime > 1) updatepri(p); p->p_slptime = 0; p->p_stat = SRUN; if (p->p_sflag & PS_INMEM) { setrunqueue(p); maybe_resched(p); break; } else { p->p_sflag |= PS_SWAPINREQ; wakeup((caddr_t)&proc0); } /* END INLINE EXPANSION */ } } } mtx_unlock_spin(&sched_lock); splx(s); } /* * The machine independent parts of mi_switch(). * Must be called at splstatclock() or higher. */ void mi_switch() { struct timeval new_switchtime; register struct proc *p = curproc; /* XXX */ #if 0 register struct rlimit *rlim; #endif u_int sched_nest; mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); /* * Compute the amount of time during which the current * process was running, and add that to its total so far. */ microuptime(&new_switchtime); if (timevalcmp(&new_switchtime, PCPU_PTR(switchtime), <)) { #if 0 /* XXX: This doesn't play well with sched_lock right now. */ printf("microuptime() went backwards (%ld.%06ld -> %ld.%06ld)\n", PCPU_GET(switchtime.tv_sec), PCPU_GET(switchtime.tv_usec), new_switchtime.tv_sec, new_switchtime.tv_usec); #endif new_switchtime = PCPU_GET(switchtime); } else { p->p_runtime += (new_switchtime.tv_usec - PCPU_GET(switchtime.tv_usec)) + (new_switchtime.tv_sec - PCPU_GET(switchtime.tv_sec)) * (int64_t)1000000; } #if 0 /* * Check if the process exceeds its cpu resource allocation. * If over max, kill it. * * XXX drop sched_lock, pickup Giant */ if (p->p_stat != SZOMB && p->p_limit->p_cpulimit != RLIM_INFINITY && p->p_runtime > p->p_limit->p_cpulimit) { rlim = &p->p_rlimit[RLIMIT_CPU]; if (p->p_runtime / (rlim_t)1000000 >= rlim->rlim_max) { mtx_unlock_spin(&sched_lock); PROC_LOCK(p); killproc(p, "exceeded maximum CPU limit"); mtx_lock_spin(&sched_lock); PROC_UNLOCK_NOSWITCH(p); } else { mtx_unlock_spin(&sched_lock); PROC_LOCK(p); psignal(p, SIGXCPU); mtx_lock_spin(&sched_lock); PROC_UNLOCK_NOSWITCH(p); if (rlim->rlim_cur < rlim->rlim_max) { /* XXX: we should make a private copy */ rlim->rlim_cur += 5; } } } #endif /* * Pick a new current process and record its start time. */ cnt.v_swtch++; PCPU_SET(switchtime, new_switchtime); CTR3(KTR_PROC, "mi_switch: old proc %p (pid %d, %s)", p, p->p_pid, p->p_comm); sched_nest = sched_lock.mtx_recurse; curproc->p_lastcpu = curproc->p_oncpu; curproc->p_oncpu = NOCPU; clear_resched(curproc); cpu_switch(); curproc->p_oncpu = PCPU_GET(cpuid); sched_lock.mtx_recurse = sched_nest; sched_lock.mtx_lock = (uintptr_t)curproc; CTR3(KTR_PROC, "mi_switch: new proc %p (pid %d, %s)", p, p->p_pid, p->p_comm); if (PCPU_GET(switchtime.tv_sec) == 0) microuptime(PCPU_PTR(switchtime)); PCPU_SET(switchticks, ticks); } /* * Change process state to be runnable, * placing it on the run queue if it is in memory, * and awakening the swapper if it isn't in memory. */ void setrunnable(p) register struct proc *p; { register int s; s = splhigh(); mtx_lock_spin(&sched_lock); switch (p->p_stat) { case 0: case SRUN: case SZOMB: case SWAIT: default: panic("setrunnable"); case SSTOP: case SSLEEP: /* e.g. when sending signals */ if (p->p_sflag & PS_CVWAITQ) cv_waitq_remove(p); else unsleep(p); break; case SIDL: break; } p->p_stat = SRUN; if (p->p_sflag & PS_INMEM) setrunqueue(p); splx(s); if (p->p_slptime > 1) updatepri(p); p->p_slptime = 0; if ((p->p_sflag & PS_INMEM) == 0) { p->p_sflag |= PS_SWAPINREQ; wakeup((caddr_t)&proc0); } else maybe_resched(p); mtx_unlock_spin(&sched_lock); } /* * Compute the priority of a process when running in user mode. * Arrange to reschedule if the resulting priority is better * than that of the current process. */ void resetpriority(p) register struct proc *p; { register unsigned int newpriority; mtx_lock_spin(&sched_lock); if (p->p_pri.pri_class == PRI_TIMESHARE) { newpriority = PUSER + p->p_estcpu / INVERSE_ESTCPU_WEIGHT + NICE_WEIGHT * (p->p_nice - PRIO_MIN); newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), PRI_MAX_TIMESHARE); p->p_pri.pri_user = newpriority; } maybe_resched(p); mtx_unlock_spin(&sched_lock); } /* ARGSUSED */ static void sched_setup(dummy) void *dummy; { callout_init(&schedcpu_callout, 1); callout_init(&roundrobin_callout, 0); /* Kick off timeout driven events by calling first time. */ roundrobin(NULL); schedcpu(NULL); } /* * 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. resetpriority() will * compute a different priority each time p_estcpu increases by * INVERSE_ESTCPU_WEIGHT * (until MAXPRI is reached). 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 principle 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. */ void schedclock(p) struct proc *p; { p->p_cpticks++; p->p_estcpu = ESTCPULIM(p->p_estcpu + 1); if ((p->p_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { resetpriority(p); if (p->p_pri.pri_level >= PUSER) p->p_pri.pri_level = p->p_pri.pri_user; } } /* * General purpose yield system call */ int yield(struct proc *p, struct yield_args *uap) { int s; p->p_retval[0] = 0; s = splhigh(); mtx_lock_spin(&sched_lock); DROP_GIANT_NOSWITCH(); p->p_pri.pri_level = PRI_MAX_TIMESHARE; setrunqueue(p); p->p_stats->p_ru.ru_nvcsw++; mi_switch(); mtx_unlock_spin(&sched_lock); PICKUP_GIANT(); splx(s); return (0); }