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Diffstat (limited to 'sys/kern/kern_synch.c')
| -rw-r--r-- | sys/kern/kern_synch.c | 932 |
1 files changed, 932 insertions, 0 deletions
diff --git a/sys/kern/kern_synch.c b/sys/kern/kern_synch.c new file mode 100644 index 0000000..a21c515 --- /dev/null +++ b/sys/kern/kern_synch.c @@ -0,0 +1,932 @@ +/*- + * 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 <sys/param.h> +#include <sys/systm.h> +#include <sys/proc.h> +#include <sys/kernel.h> +#include <sys/signalvar.h> +#include <sys/resourcevar.h> +#include <sys/vmmeter.h> +#include <sys/sysctl.h> +#include <vm/vm.h> +#include <vm/vm_extern.h> +#ifdef KTRACE +#include <sys/uio.h> +#include <sys/ktrace.h> +#endif + +#include <machine/cpu.h> +#ifdef SMP +#include <machine/smp.h> +#endif + +static void sched_setup __P((void *dummy)); +SYSINIT(sched_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, sched_setup, NULL) + +u_char curpriority; +int hogticks; +int lbolt; +int sched_quantum; /* Roundrobin scheduling quantum in ticks. */ + +static void endtsleep __P((void *)); +static void roundrobin __P((void *arg)); +static void schedcpu __P((void *arg)); +static void updatepri __P((struct proc *p)); + +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", ""); + +/* maybe_resched: Decide if you need to reschedule or not + * taking the priorities and schedulers into account. + */ +static void maybe_resched(struct proc *chk) +{ + struct proc *p = curproc; /* XXX */ + + /* + * Compare priorities if the new process is on the same scheduler, + * otherwise the one on the more realtimeish scheduler wins. + * + * XXX idle scheduler still broken because proccess stays on idle + * scheduler during waits (such as when getting FS locks). If a + * standard process becomes runaway cpu-bound, the system can lockup + * due to idle-scheduler processes in wakeup never getting any cpu. + */ + if (p == 0 || + (chk->p_priority < curpriority && RTP_PRIO_BASE(p->p_rtprio.type) == RTP_PRIO_BASE(chk->p_rtprio.type)) || + RTP_PRIO_BASE(chk->p_rtprio.type) < RTP_PRIO_BASE(p->p_rtprio.type) + ) { + need_resched(); + } +} + +int +roundrobin_interval(void) +{ + return (sched_quantum); +} + +/* + * Force switch among equal priority processes every 100ms. + */ +/* ARGSUSED */ +static void +roundrobin(arg) + void *arg; +{ +#ifndef SMP + struct proc *p = curproc; /* XXX */ +#endif + +#ifdef SMP + need_resched(); + forward_roundrobin(); +#else + if (p == 0 || RTP_PRIO_NEED_RR(p->p_rtprio.type)) + need_resched(); +#endif + + timeout(roundrobin, NULL, sched_quantum); +} + +/* + * 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. + */ +/* 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; + 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. + */ + 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 += (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_priority >= PUSER) { + if ((p != curproc) && +#ifdef SMP + p->p_oncpu == 0xff && /* idle */ +#endif + p->p_stat == SRUN && + (p->p_flag & P_INMEM) && + (p->p_priority / PPQ) != (p->p_usrpri / PPQ)) { + remrunqueue(p); + p->p_priority = p->p_usrpri; + setrunqueue(p); + } else + p->p_priority = p->p_usrpri; + } + splx(s); + } + vmmeter(); + 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(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)) + +/* + * 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 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). + */ +int +tsleep(ident, priority, wmesg, timo) + void *ident; + int priority, timo; + const char *wmesg; +{ + struct proc *p = curproc; + int s, sig, catch = priority & PCATCH; + struct callout_handle thandle; + +#ifdef KTRACE + if (p && KTRPOINT(p, KTR_CSW)) + ktrcsw(p->p_tracep, 1, 0); +#endif + s = splhigh(); + 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. + */ + splx(safepri); + splx(s); + return (0); + } + KASSERT(p != NULL, ("tsleep1")); + KASSERT(ident != NULL && p->p_stat == SRUN, ("tsleep")); + /* + * 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_priority = priority & PRIMASK; + TAILQ_INSERT_TAIL(&slpque[LOOKUP(ident)], p, p_procq); + if (timo) + thandle = timeout(endtsleep, (void *)p, 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, p->p_wchan will be 0 upon return from CURSIG. + */ + if (catch) { + p->p_flag |= P_SINTR; + if ((sig = CURSIG(p))) { + if (p->p_wchan) + unsleep(p); + p->p_stat = SRUN; + goto resume; + } + if (p->p_wchan == 0) { + catch = 0; + goto resume; + } + } else + sig = 0; + p->p_stat = SSLEEP; + p->p_stats->p_ru.ru_nvcsw++; + mi_switch(); +resume: + curpriority = p->p_usrpri; + splx(s); + p->p_flag &= ~P_SINTR; + if (p->p_flag & P_TIMEOUT) { + p->p_flag &= ~P_TIMEOUT; + if (sig == 0) { +#ifdef KTRACE + if (KTRPOINT(p, KTR_CSW)) + ktrcsw(p->p_tracep, 0, 0); +#endif + return (EWOULDBLOCK); + } + } else if (timo) + untimeout(endtsleep, (void *)p, thandle); + if (catch && (sig != 0 || (sig = CURSIG(p)))) { +#ifdef KTRACE + if (KTRPOINT(p, KTR_CSW)) + ktrcsw(p->p_tracep, 0, 0); +#endif + if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) + return (EINTR); + return (ERESTART); + } +#ifdef KTRACE + if (KTRPOINT(p, KTR_CSW)) + ktrcsw(p->p_tracep, 0, 0); +#endif + return (0); +} + +/* + * asleep() - async sleep call. Place process on wait queue and return + * immediately without blocking. The process stays runnable until await() + * 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 tsleep(). + * + * The timeout, if any, is not initiated until await() is called. The sleep + * priority, signal, and timeout is specified in the asleep() call but may be + * overriden in the await() call. + * + * <<<<<<<< EXPERIMENTAL, UNTESTED >>>>>>>>>> + */ + +int +asleep(void *ident, int priority, const char *wmesg, int timo) +{ + struct proc *p = curproc; + int s; + + /* + * splhigh() while manipulating sleep structures and slpque. + * + * Remove preexisting wait condition (if any) and place process + * on appropriate slpque, but do not put process to sleep. + */ + + s = splhigh(); + + 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_procq); + } + + splx(s); + + return(0); +} + +/* + * await() - wait for async condition to occur. The process blocks until + * wakeup() is called on the most recent asleep() address. If wakeup is called + * priority to await(), await() winds up being a NOP. + * + * If await() is called more then once (without an intervening asleep() call), + * await() 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 +await(int priority, int timo) +{ + struct proc *p = curproc; + int s; + + s = splhigh(); + + if (p->p_wchan != NULL) { + struct callout_handle thandle; + int sig; + int catch; + + /* + * The call to await() 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) + thandle = timeout(endtsleep, (void *)p, timo); + + sig = 0; + catch = priority & PCATCH; + + if (catch) { + p->p_flag |= P_SINTR; + if ((sig = CURSIG(p))) { + if (p->p_wchan) + unsleep(p); + p->p_stat = SRUN; + goto resume; + } + if (p->p_wchan == NULL) { + catch = 0; + goto resume; + } + } + p->p_stat = SSLEEP; + p->p_stats->p_ru.ru_nvcsw++; + mi_switch(); +resume: + curpriority = p->p_usrpri; + + splx(s); + p->p_flag &= ~P_SINTR; + if (p->p_flag & P_TIMEOUT) { + p->p_flag &= ~P_TIMEOUT; + if (sig == 0) { +#ifdef KTRACE + if (KTRPOINT(p, KTR_CSW)) + ktrcsw(p->p_tracep, 0, 0); +#endif + return (EWOULDBLOCK); + } + } else if (timo) + untimeout(endtsleep, (void *)p, thandle); + if (catch && (sig != 0 || (sig = CURSIG(p)))) { +#ifdef KTRACE + if (KTRPOINT(p, KTR_CSW)) + ktrcsw(p->p_tracep, 0, 0); +#endif + if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) + return (EINTR); + return (ERESTART); + } +#ifdef KTRACE + if (KTRPOINT(p, KTR_CSW)) + ktrcsw(p->p_tracep, 0, 0); +#endif + } else { + /* + * If as_priority is 0, await() 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(); + } + splx(s); + } + + /* + * clear p_asleep.as_priority as an indication that await() has been + * called. If await() is called again without an intervening asleep(), + * await() is still effectively a NOP but the above mi_switch() code + * is triggered as a safety. + */ + p->p_asleep.as_priority = 0; + + return (0); +} + +/* + * Implement timeout for tsleep or asleep()/await() + * + * 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. + */ +static void +endtsleep(arg) + void *arg; +{ + register struct proc *p; + int s; + + p = (struct proc *)arg; + s = splhigh(); + if (p->p_wchan) { + if (p->p_stat == SSLEEP) + setrunnable(p); + else + unsleep(p); + p->p_flag |= P_TIMEOUT; + } + splx(s); +} + +/* + * Remove a process from its wait queue + */ +void +unsleep(p) + register struct proc *p; +{ + int s; + + s = splhigh(); + if (p->p_wchan) { + TAILQ_REMOVE(&slpque[LOOKUP(p->p_wchan)], p, p_procq); + p->p_wchan = 0; + } + 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(); + qp = &slpque[LOOKUP(ident)]; +restart: + TAILQ_FOREACH(p, qp, p_procq) { + if (p->p_wchan == ident) { + TAILQ_REMOVE(qp, p, p_procq); + p->p_wchan = 0; + 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); + maybe_resched(p); + } else { + p->p_flag |= P_SWAPINREQ; + wakeup((caddr_t)&proc0); + } + /* END INLINE EXPANSION */ + goto restart; + } + } + } + splx(s); +} + +/* + * Make a process sleeping on the specified identifier runnable. + * May wake more than one process if a target prcoess is currently + * swapped out. + */ +void +wakeup_one(ident) + register void *ident; +{ + register struct slpquehead *qp; + register struct proc *p; + int s; + + s = splhigh(); + qp = &slpque[LOOKUP(ident)]; + + TAILQ_FOREACH(p, qp, p_procq) { + if (p->p_wchan == ident) { + TAILQ_REMOVE(qp, p, p_procq); + p->p_wchan = 0; + 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); + maybe_resched(p); + break; + } else { + p->p_flag |= P_SWAPINREQ; + wakeup((caddr_t)&proc0); + } + /* END INLINE EXPANSION */ + } + } + } + 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 */ + register struct rlimit *rlim; + int x; + + /* + * XXX this spl is almost unnecessary. It is partly to allow for + * sloppy callers that don't do it (issignal() via CURSIG() is the + * main offender). It is partly to work around a bug in the i386 + * cpu_switch() (the ipl is not preserved). We ran for years + * without it. I think there was only a interrupt latency problem. + * The main caller, tsleep(), does an splx() a couple of instructions + * after calling here. The buggy caller, issignal(), usually calls + * here at spl0() and sometimes returns at splhigh(). The process + * then runs for a little too long at splhigh(). The ipl gets fixed + * when the process returns to user mode (or earlier). + * + * It would probably be better to always call here at spl0(). Callers + * are prepared to give up control to another process, so they must + * be prepared to be interrupted. The clock stuff here may not + * actually need splstatclock(). + */ + x = splstatclock(); + +#ifdef SIMPLELOCK_DEBUG + if (p->p_simple_locks) + printf("sleep: holding simple lock\n"); +#endif + /* + * 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, &switchtime, <)) { + printf("microuptime() went backwards (%ld.%06ld -> %ld,%06ld)\n", + switchtime.tv_sec, switchtime.tv_usec, + new_switchtime.tv_sec, new_switchtime.tv_usec); + new_switchtime = switchtime; + } else { + p->p_runtime += (new_switchtime.tv_usec - switchtime.tv_usec) + + (new_switchtime.tv_sec - switchtime.tv_sec) * (int64_t)1000000; + } + + /* + * Check if the process exceeds its cpu resource allocation. + * If over max, kill it. + */ + 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) { + 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. + */ + cnt.v_swtch++; + switchtime = new_switchtime; + cpu_switch(p); + if (switchtime.tv_sec == 0) + microuptime(&switchtime); + switchticks = ticks; + + splx(x); +} + +/* + * 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(); + switch (p->p_stat) { + case 0: + case SRUN: + case SZOMB: + default: + panic("setrunnable"); + case SSTOP: + case SSLEEP: + unsleep(p); /* 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); + } + else + maybe_resched(p); +} + +/* + * 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; + + if (p->p_rtprio.type == RTP_PRIO_NORMAL) { + newpriority = PUSER + p->p_estcpu / INVERSE_ESTCPU_WEIGHT + + NICE_WEIGHT * p->p_nice; + newpriority = min(newpriority, MAXPRI); + p->p_usrpri = newpriority; + } + maybe_resched(p); +} + +/* ARGSUSED */ +static void +sched_setup(dummy) + void *dummy; +{ + /* 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_priority >= PUSER) + p->p_priority = p->p_usrpri; + } +} |
