/*- * 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: src/sys/kern/kern_synch.c,v 1.87.2.6 2002/10/13 07:29:53 kbyanc Exp $ * $DragonFly: src/sys/kern/kern_synch.c,v 1.32 2004/04/10 20:55:23 dillon Exp $ */ #include "opt_ktrace.h" #include #include #include #include #include #include #include #include #include #ifdef KTRACE #include #include #endif #include #include #include #include static void sched_setup (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. */ int ncpus; int ncpus2, ncpus2_shift, ncpus2_mask; static struct callout loadav_callout; struct loadavg averunnable = { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */ /* * Constants for averages over 1, 5, and 15 minutes * when sampling at 5 second intervals. */ static fixpt_t cexp[3] = { 0.9200444146293232 * FSCALE, /* exp(-1/12) */ 0.9834714538216174 * FSCALE, /* exp(-1/60) */ 0.9944598480048967 * FSCALE, /* exp(-1/180) */ }; static void endtsleep (void *); static void loadav (void *arg); static void roundrobin (void *arg); static void schedcpu (void *arg); static void updatepri (struct proc *p); static void crit_panicints(void); 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", ""); int roundrobin_interval(void) { return (sched_quantum); } /* * Force switch among equal priority processes every 100ms. * * WARNING! The MP lock is not held on ipi message remotes. */ #ifdef SMP static void roundrobin_remote(void *arg) { struct proc *p = lwkt_preempted_proc(); if (p == NULL || RTP_PRIO_NEED_RR(p->p_rtprio.type)) need_user_resched(); } #endif static void roundrobin(void *arg) { struct proc *p = lwkt_preempted_proc(); if (p == NULL || RTP_PRIO_NEED_RR(p->p_rtprio.type)) need_user_resched(); #ifdef SMP lwkt_send_ipiq_mask(mycpu->gd_other_cpus, roundrobin_remote, NULL); #endif timeout(roundrobin, NULL, sched_quantum); } #ifdef SMP void resched_cpus(u_int32_t mask) { lwkt_send_ipiq_mask(mask, roundrobin_remote, NULL); } #endif /* * The load average is scaled by FSCALE (2048 typ). The estimated cpu is * incremented at a rate of ESTCPUVFREQ per second (40hz typ), but this is * divided up across all cpu bound processes running in the system so an * individual process will get less under load. ESTCPULIM typicaly caps * out at ESTCPUMAX (around 376, or 11 nice levels). * * Generally speaking the decay equation needs to break-even on growth * at the limit at all load levels >= 1.0, so if the estimated cpu for * a process increases by (ESTVCPUFREQ / load) per second, then the decay * should reach this value when estcpu reaches ESTCPUMAX. That calculation * is: * * ESTCPUMAX * decay = ESTCPUVFREQ / load * decay = ESTCPUVFREQ / (load * ESTCPUMAX) * decay = estcpu * 0.053 / load * * If the load is less then 1.0 we assume a load of 1.0. */ #define cload(loadav) ((loadav) < FSCALE ? FSCALE : (loadav)) #define decay_cpu(loadav,estcpu) \ ((estcpu) * (FSCALE * ESTCPUVFREQ / ESTCPUMAX) / cload(loadav)) /* 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, once a second. */ /* ARGSUSED */ static void schedcpu(void *arg) { fixpt_t loadfac = averunnable.ldavg[0]; struct proc *p; int s; unsigned int ndecay; FOREACH_PROC_IN_SYSTEM(p) { /* * 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. */ 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) continue; s = splhigh(); /* prevent state changes and protect run queue */ /* * p_pctcpu is only for ps. */ #if (FSHIFT >= CCPU_SHIFT) p->p_pctcpu += (ESTCPUFREQ == 100)? ((fixpt_t) p->p_cpticks) << (FSHIFT - CCPU_SHIFT): 100 * (((fixpt_t) p->p_cpticks) << (FSHIFT - CCPU_SHIFT)) / ESTCPUFREQ; #else p->p_pctcpu += ((FSCALE - ccpu) * (p->p_cpticks * FSCALE / ESTCPUFREQ)) >> FSHIFT; #endif p->p_cpticks = 0; ndecay = decay_cpu(loadfac, p->p_estcpu); if (p->p_estcpu > ndecay) p->p_estcpu -= ndecay; else p->p_estcpu = 0; resetpriority(p); splx(s); } wakeup((caddr_t)&lbolt); timeout(schedcpu, (void *)0, hz); } /* * 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. */ static void updatepri(struct proc *p) { unsigned int ndecay; ndecay = decay_cpu(averunnable.ldavg[0], p->p_estcpu) * p->p_slptime; if (p->p_estcpu > ndecay) p->p_estcpu -= ndecay; else p->p_estcpu = 0; 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, thread) slpque[TABLESIZE]; #define LOOKUP(x) (((intptr_t)(x) >> 8) & (TABLESIZE - 1)) /* * During autoconfiguration or after a panic, a sleep will simply * lower the priority briefly to allow interrupts, then return. * The priority to be used (safepri) is machine-dependent, thus this * value is initialized and maintained in the machine-dependent layers. * This priority will typically be 0, or the lowest priority * that is safe for use on the interrupt stack; it can be made * higher to block network software interrupts after panics. */ int safepri; 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 flags 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). * * Note that if we are a process, we release_curproc() before messing with * the LWKT scheduler. */ int tsleep(void *ident, int flags, const char *wmesg, int timo) { struct thread *td = curthread; struct proc *p = td->td_proc; /* may be NULL */ int sig = 0, catch = flags & PCATCH; int id = LOOKUP(ident); struct callout_handle thandle; /* * NOTE: removed KTRPOINT, it could cause races due to blocking * even in stable. Just scrap it for now. */ 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. */ crit_panicints(); return (0); } KKASSERT(td != &mycpu->gd_idlethread); /* you must be kidding! */ crit_enter_quick(td); KASSERT(ident != NULL, ("tsleep: no ident")); KASSERT(p == NULL || p->p_stat == SRUN, ("tsleep %p %s %d", ident, wmesg, p->p_stat)); td->td_wchan = ident; td->td_wmesg = wmesg; if (p) { if (flags & PNORESCHED) td->td_flags |= TDF_NORESCHED; release_curproc(p); p->p_slptime = 0; } lwkt_deschedule_self(td); TAILQ_INSERT_TAIL(&slpque[id], td, td_threadq); if (timo) thandle = timeout(endtsleep, (void *)td, timo); /* * 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, td->td_wchan will be 0 upon return from CURSIG. */ if (p) { if (catch) { p->p_flag |= P_SINTR; if ((sig = CURSIG(p))) { if (td->td_wchan) { unsleep(td); lwkt_schedule_self(td); } p->p_stat = SRUN; goto resume; } if (td->td_wchan == NULL) { catch = 0; goto resume; } } else { sig = 0; } /* * If we are not the current process we have to remove ourself * from the run queue. */ KASSERT(p->p_stat == SRUN, ("PSTAT NOT SRUN %d %d", p->p_pid, p->p_stat)); /* * If this is the current 'user' process schedule another one. */ clrrunnable(p, SSLEEP); p->p_stats->p_ru.ru_nvcsw++; mi_switch(p); KASSERT(p->p_stat == SRUN, ("tsleep: stat not srun")); } else { lwkt_switch(); } resume: if (p) p->p_flag &= ~P_SINTR; crit_exit_quick(td); td->td_flags &= ~TDF_NORESCHED; if (td->td_flags & TDF_TIMEOUT) { td->td_flags &= ~TDF_TIMEOUT; if (sig == 0) return (EWOULDBLOCK); } else if (timo) { untimeout(endtsleep, (void *)td, thandle); } else if (td->td_wmesg) { /* * This can happen if a thread is woken up directly. Clear * wmesg to avoid debugging confusion. */ td->td_wmesg = NULL; } /* inline of iscaught() */ if (p) { if (catch && (sig != 0 || (sig = CURSIG(p)))) { if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) return (EINTR); return (ERESTART); } } return (0); } /* * Implement the timeout for tsleep. We interlock against * wchan when setting TDF_TIMEOUT. For processes we remove * the sleep if the process is stopped rather then sleeping, * so it remains stopped. */ static void endtsleep(void *arg) { thread_t td = arg; struct proc *p; crit_enter(); if (td->td_wchan) { td->td_flags |= TDF_TIMEOUT; if ((p = td->td_proc) != NULL) { if (p->p_stat == SSLEEP) setrunnable(p); else unsleep(td); } else { unsleep(td); lwkt_schedule(td); } } crit_exit(); } /* * Remove a process from its wait queue */ void unsleep(struct thread *td) { crit_enter(); if (td->td_wchan) { #if 0 if (p->p_flag & P_XSLEEP) { struct xwait *w = p->p_wchan; TAILQ_REMOVE(&w->waitq, p, p_procq); p->p_flag &= ~P_XSLEEP; } else #endif TAILQ_REMOVE(&slpque[LOOKUP(td->td_wchan)], td, td_threadq); td->td_wchan = NULL; } crit_exit(); } #if 0 /* * Make all processes sleeping on the explicit lock structure runnable. */ void xwakeup(struct xwait *w) { struct proc *p; crit_enter(); ++w->gen; while ((p = TAILQ_FIRST(&w->waitq)) != NULL) { TAILQ_REMOVE(&w->waitq, p, p_procq); KASSERT(p->p_wchan == w && (p->p_flag & P_XSLEEP), ("xwakeup: wchan mismatch for %p (%p/%p) %08x", p, p->p_wchan, w, p->p_flag & P_XSLEEP)); p->p_wchan = NULL; p->p_flag &= ~P_XSLEEP; if (p->p_stat == SSLEEP) { /* OPTIMIZED EXPANSION OF setrunnable(p); */ if (p->p_slptime > 1) updatepri(p); p->p_slptime = 0; p->p_stat = SRUN; if (p->p_flag & P_INMEM) { setrunqueue(p); } else { p->p_flag |= P_SWAPINREQ; wakeup((caddr_t)&proc0); } } } crit_exit(); } #endif /* * Make all processes sleeping on the specified identifier runnable. */ static void _wakeup(void *ident, int count) { struct slpquehead *qp; struct thread *td; struct thread *ntd; struct proc *p; int id = LOOKUP(ident); crit_enter(); qp = &slpque[id]; restart: for (td = TAILQ_FIRST(qp); td != NULL; td = ntd) { ntd = TAILQ_NEXT(td, td_threadq); if (td->td_wchan == ident) { TAILQ_REMOVE(qp, td, td_threadq); td->td_wchan = NULL; if ((p = td->td_proc) != NULL && p->p_stat == SSLEEP) { /* OPTIMIZED EXPANSION OF setrunnable(p); */ if (p->p_slptime > 1) updatepri(p); p->p_slptime = 0; p->p_stat = SRUN; if (p->p_flag & P_INMEM) { setrunqueue(p); } else { p->p_flag |= P_SWAPINREQ; wakeup((caddr_t)&proc0); } /* END INLINE EXPANSION */ } else if (p == NULL) { lwkt_schedule(td); } if (--count == 0) break; goto restart; } } crit_exit(); } void wakeup(void *ident) { _wakeup(ident, 0); } void wakeup_one(void *ident) { _wakeup(ident, 1); } /* * The machine independent parts of mi_switch(). * * 'p' must be the current process. */ void mi_switch(struct proc *p) { thread_t td = p->p_thread; struct rlimit *rlim; u_int64_t ttime; KKASSERT(td == mycpu->gd_curthread); crit_enter_quick(td); /* * Check if the process exceeds its cpu resource allocation. * If over max, kill it. Time spent in interrupts is not * included. YYY 64 bit match is expensive. Ick. */ ttime = td->td_sticks + td->td_uticks; if (p->p_stat != SZOMB && p->p_limit->p_cpulimit != RLIM_INFINITY && ttime > p->p_limit->p_cpulimit) { rlim = &p->p_rlimit[RLIMIT_CPU]; if (ttime / (rlim_t)1000000 >= rlim->rlim_max) { killproc(p, "exceeded maximum CPU limit"); } else { psignal(p, SIGXCPU); if (rlim->rlim_cur < rlim->rlim_max) { /* XXX: we should make a private copy */ rlim->rlim_cur += 5; } } } /* * Pick a new current process and record its start time. If we * are in a SSTOPped state we deschedule ourselves. YYY this needs * to be cleaned up, remember that LWKTs stay on their run queue * which works differently then the user scheduler which removes * the process from the runq when it runs it. */ mycpu->gd_cnt.v_swtch++; if (p->p_stat == SSTOP) lwkt_deschedule_self(td); lwkt_switch(); crit_exit_quick(td); } /* * 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(struct proc *p) { int s; s = splhigh(); switch (p->p_stat) { case 0: case SRUN: case SZOMB: default: panic("setrunnable"); case SSTOP: case SSLEEP: unsleep(p->p_thread); /* e.g. when sending signals */ break; case SIDL: break; } p->p_stat = SRUN; if (p->p_flag & P_INMEM) setrunqueue(p); splx(s); if (p->p_slptime > 1) updatepri(p); p->p_slptime = 0; if ((p->p_flag & P_INMEM) == 0) { p->p_flag |= P_SWAPINREQ; wakeup((caddr_t)&proc0); } } /* * Change the process state to NOT be runnable, removing it from the run * queue. */ void clrrunnable(struct proc *p, int stat) { crit_enter_quick(p->p_thread); if (p->p_stat == SRUN && (p->p_flag & P_ONRUNQ)) remrunqueue(p); p->p_stat = stat; crit_exit_quick(p->p_thread); } /* * 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(struct proc *p) { unsigned int newpriority; int opq; int npq; /* * Set p_priority for general process comparisons */ switch(p->p_rtprio.type) { case RTP_PRIO_REALTIME: p->p_priority = PRIBASE_REALTIME + p->p_rtprio.prio; return; case RTP_PRIO_NORMAL: break; case RTP_PRIO_IDLE: p->p_priority = PRIBASE_IDLE + p->p_rtprio.prio; return; case RTP_PRIO_THREAD: p->p_priority = PRIBASE_THREAD + p->p_rtprio.prio; return; } /* * NORMAL priorities fall through. These are based on niceness * and cpu use. */ newpriority = NICE_ADJUST(p->p_nice - PRIO_MIN) + p->p_estcpu / ESTCPURAMP; newpriority = min(newpriority, MAXPRI); npq = newpriority / PPQ; crit_enter(); opq = (p->p_priority & PRIMASK) / PPQ; if (p->p_stat == SRUN && (p->p_flag & P_ONRUNQ) && opq != npq) { /* * We have to move the process to another queue */ remrunqueue(p); p->p_priority = PRIBASE_NORMAL + newpriority; setrunqueue(p); } else { /* * We can just adjust the priority and it will be picked * up later. */ KKASSERT(opq == npq || (p->p_flag & P_ONRUNQ) == 0); p->p_priority = PRIBASE_NORMAL + newpriority; } crit_exit(); } /* * Compute a tenex style load average of a quantity on * 1, 5 and 15 minute intervals. */ static void loadav(void *arg) { int i, nrun; struct loadavg *avg; struct proc *p; avg = &averunnable; nrun = 0; FOREACH_PROC_IN_SYSTEM(p) { switch (p->p_stat) { case SRUN: case SIDL: nrun++; } } for (i = 0; i < 3; i++) avg->ldavg[i] = (cexp[i] * avg->ldavg[i] + nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT; /* * Schedule the next update to occur after 5 seconds, but add a * random variation to avoid synchronisation with processes that * run at regular intervals. */ callout_reset(&loadav_callout, hz * 4 + (int)(random() % (hz * 2 + 1)), loadav, NULL); } /* ARGSUSED */ static void sched_setup(void *dummy) { callout_init(&loadav_callout); /* Kick off timeout driven events by calling first time. */ roundrobin(NULL); schedcpu(NULL); loadav(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. * * The actual schedulerclock interrupt rate is ESTCPUFREQ, but we generally * want to ramp-up at a faster rate, ESTCPUVFREQ, so p_estcpu is scaled * by (ESTCPUVFREQ / ESTCPUFREQ). You can control the ramp-up/ramp-down * rate by adjusting ESTCPUVFREQ in sys/proc.h in integer multiples * of ESTCPUFREQ. * * WARNING! called from a fast-int or an IPI, the MP lock MIGHT NOT BE HELD * and we cannot block. */ void schedulerclock(void *dummy) { struct thread *td; struct proc *p; td = curthread; if ((p = td->td_proc) != NULL) { p->p_cpticks++; /* cpticks runs at ESTCPUFREQ */ p->p_estcpu = ESTCPULIM(p->p_estcpu + ESTCPUVFREQ / ESTCPUFREQ); if (try_mplock()) { resetpriority(p); rel_mplock(); } } } static void crit_panicints(void) { int s; int cpri; s = splhigh(); cpri = crit_panic_save(); splx(safepri); crit_panic_restore(cpri); splx(s); }