/* $NetBSD: kern_synch.c,v 1.186 2007/03/04 06:03:06 christos Exp $ */ /*- * Copyright (c) 1999, 2000, 2004, 2006, 2007 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, * NASA Ames Research Center, by Charles M. Hannum, and by Andrew Doran. * * 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 NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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. */ /*- * 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. 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 */ #include __KERNEL_RCSID(0, "$NetBSD: kern_synch.c,v 1.186 2007/03/04 06:03:06 christos Exp $"); #include "opt_ddb.h" #include "opt_kstack.h" #include "opt_lockdebug.h" #include "opt_multiprocessor.h" #include "opt_perfctrs.h" #define __MUTEX_PRIVATE #include #include #include #include #include #include #if defined(PERFCTRS) #include #endif #include #include #include #include #include #include #include #include #include int lbolt; /* once a second sleep address */ int rrticks; /* number of hardclock ticks per roundrobin() */ /* * The global scheduler state. */ kmutex_t sched_mutex; /* global sched state mutex */ struct prochd sched_qs[RUNQUE_NQS]; /* run queues */ volatile uint32_t sched_whichqs; /* bitmap of non-empty queues */ void schedcpu(void *); void updatepri(struct lwp *); void sched_unsleep(struct lwp *); void sched_changepri(struct lwp *, pri_t); void sched_lendpri(struct lwp *, pri_t); struct callout schedcpu_ch = CALLOUT_INITIALIZER_SETFUNC(schedcpu, NULL); static unsigned int schedcpu_ticks; syncobj_t sleep_syncobj = { SOBJ_SLEEPQ_SORTED, sleepq_unsleep, sleepq_changepri, sleepq_lendpri, syncobj_noowner, }; syncobj_t sched_syncobj = { SOBJ_SLEEPQ_SORTED, sched_unsleep, sched_changepri, sched_lendpri, syncobj_noowner, }; /* * Force switch among equal priority processes every 100ms. * Called from hardclock every hz/10 == rrticks hardclock ticks. */ /* ARGSUSED */ void roundrobin(struct cpu_info *ci) { struct schedstate_percpu *spc = &ci->ci_schedstate; spc->spc_rrticks = rrticks; if (curlwp != NULL) { if (spc->spc_flags & SPCF_SEENRR) { /* * The process has already been through a roundrobin * without switching and may be hogging the CPU. * Indicate that the process should yield. */ spc->spc_flags |= SPCF_SHOULDYIELD; } else spc->spc_flags |= SPCF_SEENRR; } cpu_need_resched(curcpu()); } #define PPQ (128 / RUNQUE_NQS) /* priorities per queue */ #define NICE_WEIGHT 2 /* priorities per nice level */ #define ESTCPU_SHIFT 11 #define ESTCPU_MAX ((NICE_WEIGHT * PRIO_MAX - PPQ) << ESTCPU_SHIFT) #define ESTCPULIM(e) min((e), ESTCPU_MAX) /* * 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 hardclock updates p_estcpu and p_cpticks independently. * * 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)) static fixpt_t decay_cpu(fixpt_t loadfac, fixpt_t estcpu) { if (estcpu == 0) { return 0; } #if !defined(_LP64) /* avoid 64bit arithmetics. */ #define FIXPT_MAX ((fixpt_t)((UINTMAX_C(1) << sizeof(fixpt_t) * CHAR_BIT) - 1)) if (__predict_true(loadfac <= FIXPT_MAX / ESTCPU_MAX)) { return estcpu * loadfac / (loadfac + FSCALE); } #endif /* !defined(_LP64) */ return (uint64_t)estcpu * loadfac / (loadfac + FSCALE); } /* * For all load averages >= 1 and max p_estcpu of (255 << ESTCPU_SHIFT), * sleeping for at least seven times the loadfactor will decay p_estcpu to * less than (1 << ESTCPU_SHIFT). * * note that our ESTCPU_MAX is actually much smaller than (255 << ESTCPU_SHIFT). */ static fixpt_t decay_cpu_batch(fixpt_t loadfac, fixpt_t estcpu, unsigned int n) { if ((n << FSHIFT) >= 7 * loadfac) { return 0; } while (estcpu != 0 && n > 1) { estcpu = decay_cpu(loadfac, estcpu); n--; } return estcpu; } /* decay 95% of `p_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ /* * 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 dont 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 /* * schedcpu: * * Recompute process priorities, every hz ticks. * * XXXSMP This needs to be reorganised in order to reduce the locking * burden. */ /* ARGSUSED */ void schedcpu(void *arg) { fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); struct rlimit *rlim; struct lwp *l; struct proc *p; int minslp, clkhz, sig; long runtm; schedcpu_ticks++; mutex_enter(&proclist_mutex); PROCLIST_FOREACH(p, &allproc) { /* * 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. */ minslp = 2; mutex_enter(&p->p_smutex); runtm = p->p_rtime.tv_sec; LIST_FOREACH(l, &p->p_lwps, l_sibling) { lwp_lock(l); runtm += l->l_rtime.tv_sec; l->l_swtime++; if (l->l_stat == LSSLEEP || l->l_stat == LSSTOP || l->l_stat == LSSUSPENDED) { l->l_slptime++; minslp = min(minslp, l->l_slptime); } else minslp = 0; lwp_unlock(l); } p->p_pctcpu = (p->p_pctcpu * ccpu) >> FSHIFT; /* * Check if the process exceeds its CPU resource allocation. * If over max, kill it. */ rlim = &p->p_rlimit[RLIMIT_CPU]; sig = 0; if (runtm >= rlim->rlim_cur) { if (runtm >= rlim->rlim_max) sig = SIGKILL; else { sig = SIGXCPU; if (rlim->rlim_cur < rlim->rlim_max) rlim->rlim_cur += 5; } } /* * If the process has run for more than autonicetime, reduce * priority to give others a chance. */ if (autonicetime && runtm > autonicetime && p->p_nice == NZERO && kauth_cred_geteuid(p->p_cred)) { mutex_spin_enter(&p->p_stmutex); p->p_nice = autoniceval + NZERO; resetprocpriority(p); mutex_spin_exit(&p->p_stmutex); } /* * If the process has slept the entire second, * stop recalculating its priority until it wakes up. */ if (minslp <= 1) { /* * p_pctcpu is only for ps. */ mutex_spin_enter(&p->p_stmutex); clkhz = stathz != 0 ? stathz : hz; #if (FSHIFT >= CCPU_SHIFT) p->p_pctcpu += (clkhz == 100)? ((fixpt_t) p->p_cpticks) << (FSHIFT - CCPU_SHIFT): 100 * (((fixpt_t) p->p_cpticks) << (FSHIFT - CCPU_SHIFT)) / clkhz; #else p->p_pctcpu += ((FSCALE - ccpu) * (p->p_cpticks * FSCALE / clkhz)) >> FSHIFT; #endif p->p_cpticks = 0; p->p_estcpu = decay_cpu(loadfac, p->p_estcpu); LIST_FOREACH(l, &p->p_lwps, l_sibling) { lwp_lock(l); if (l->l_slptime <= 1 && l->l_priority >= PUSER) resetpriority(l); lwp_unlock(l); } mutex_spin_exit(&p->p_stmutex); } mutex_exit(&p->p_smutex); if (sig) { psignal(p, sig); } } mutex_exit(&proclist_mutex); uvm_meter(); wakeup((void *)&lbolt); callout_schedule(&schedcpu_ch, hz); } /* * Recalculate the priority of a process after it has slept for a while. */ void updatepri(struct lwp *l) { struct proc *p = l->l_proc; fixpt_t loadfac; LOCK_ASSERT(lwp_locked(l, NULL)); KASSERT(l->l_slptime > 1); loadfac = loadfactor(averunnable.ldavg[0]); l->l_slptime--; /* the first time was done in schedcpu */ /* XXX NJWLWP */ /* XXXSMP occasionally unlocked, should be per-LWP */ p->p_estcpu = decay_cpu_batch(loadfac, p->p_estcpu, l->l_slptime); resetpriority(l); } /* * 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; /* * OBSOLETE INTERFACE * * 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 interlock is held until we are on a sleep queue. The interlock will * be locked before returning back to the caller unless the PNORELOCK flag * is specified, in which case the interlock will always be unlocked upon * return. */ int ltsleep(wchan_t ident, pri_t priority, const char *wmesg, int timo, volatile struct simplelock *interlock) { struct lwp *l = curlwp; sleepq_t *sq; int error, catch; if (sleepq_dontsleep(l)) { (void)sleepq_abort(NULL, 0); if ((priority & PNORELOCK) != 0) simple_unlock(interlock); return 0; } sq = sleeptab_lookup(&sleeptab, ident); sleepq_enter(sq, l); if (interlock != NULL) { LOCK_ASSERT(simple_lock_held(interlock)); simple_unlock(interlock); } catch = priority & PCATCH; sleepq_block(sq, priority & PRIMASK, ident, wmesg, timo, catch, &sleep_syncobj); error = sleepq_unblock(timo, catch); if (interlock != NULL && (priority & PNORELOCK) == 0) simple_lock(interlock); return error; } /* * General sleep call for situations where a wake-up is not expected. */ int kpause(const char *wmesg, bool intr, int timo, kmutex_t *mtx) { struct lwp *l = curlwp; sleepq_t *sq; int error; if (sleepq_dontsleep(l)) return sleepq_abort(NULL, 0); if (mtx != NULL) mutex_exit(mtx); sq = sleeptab_lookup(&sleeptab, l); sleepq_enter(sq, l); sleepq_block(sq, sched_kpri(l), l, wmesg, timo, intr, &sleep_syncobj); error = sleepq_unblock(timo, intr); if (mtx != NULL) mutex_enter(mtx); return error; } /* * OBSOLETE INTERFACE * * Make all processes sleeping on the specified identifier runnable. */ void wakeup(wchan_t ident) { sleepq_t *sq; if (cold) return; sq = sleeptab_lookup(&sleeptab, ident); sleepq_wake(sq, ident, (u_int)-1); } /* * OBSOLETE INTERFACE * * Make the highest priority process first in line on the specified * identifier runnable. */ void wakeup_one(wchan_t ident) { sleepq_t *sq; if (cold) return; sq = sleeptab_lookup(&sleeptab, ident); sleepq_wake(sq, ident, 1); } /* * General yield call. Puts the current process back on its run queue and * performs a voluntary context switch. Should only be called when the * current process explicitly requests it (eg sched_yield(2) in compat code). */ void yield(void) { struct lwp *l = curlwp; KERNEL_UNLOCK_ALL(l, &l->l_biglocks); lwp_lock(l); if (l->l_stat == LSONPROC) { KASSERT(lwp_locked(l, &sched_mutex)); l->l_priority = l->l_usrpri; } l->l_nvcsw++; mi_switch(l, NULL); KERNEL_LOCK(l->l_biglocks, l); } /* * General preemption call. Puts the current process back on its run queue * and performs an involuntary context switch. */ void preempt(void) { struct lwp *l = curlwp; KERNEL_UNLOCK_ALL(l, &l->l_biglocks); lwp_lock(l); if (l->l_stat == LSONPROC) { KASSERT(lwp_locked(l, &sched_mutex)); l->l_priority = l->l_usrpri; } l->l_nivcsw++; (void)mi_switch(l, NULL); KERNEL_LOCK(l->l_biglocks, l); } /* * The machine independent parts of context switch. Switch to "new" * if non-NULL, otherwise let cpu_switch choose the next lwp. * * Returns 1 if another process was actually run. */ int mi_switch(struct lwp *l, struct lwp *newl) { struct schedstate_percpu *spc; struct timeval tv; int retval, oldspl; long s, u; LOCK_ASSERT(lwp_locked(l, NULL)); #ifdef LOCKDEBUG spinlock_switchcheck(); simple_lock_switchcheck(); #endif #ifdef KSTACK_CHECK_MAGIC kstack_check_magic(l); #endif /* * It's safe to read the per CPU schedstate unlocked here, as all we * are after is the run time and that's guarenteed to have been last * updated by this CPU. */ KDASSERT(l->l_cpu == curcpu()); spc = &l->l_cpu->ci_schedstate; /* * Compute the amount of time during which the current * process was running. */ microtime(&tv); u = l->l_rtime.tv_usec + (tv.tv_usec - spc->spc_runtime.tv_usec); s = l->l_rtime.tv_sec + (tv.tv_sec - spc->spc_runtime.tv_sec); if (u < 0) { u += 1000000; s--; } else if (u >= 1000000) { u -= 1000000; s++; } l->l_rtime.tv_usec = u; l->l_rtime.tv_sec = s; /* Count time spent in current system call */ SYSCALL_TIME_SLEEP(l); /* * XXXSMP If we are using h/w performance counters, save context. */ #if PERFCTRS if (PMC_ENABLED(l->l_proc)) { pmc_save_context(l->l_proc); } #endif /* * Acquire the sched_mutex if necessary. It will be released by * cpu_switch once it has decided to idle, or picked another LWP * to run. */ #if defined(MULTIPROCESSOR) || defined(LOCKDEBUG) if (l->l_mutex != &sched_mutex) { mutex_spin_enter(&sched_mutex); lwp_unlock(l); } #endif /* * If on the CPU and we have gotten this far, then we must yield. */ KASSERT(l->l_stat != LSRUN); if (l->l_stat == LSONPROC) { KASSERT(lwp_locked(l, &sched_mutex)); l->l_stat = LSRUN; setrunqueue(l); } uvmexp.swtch++; /* * Process is about to yield the CPU; clear the appropriate * scheduling flags. */ spc->spc_flags &= ~SPCF_SWITCHCLEAR; LOCKDEBUG_BARRIER(&sched_mutex, 1); /* * Switch to the new current LWP. When we run again, we'll * return back here. */ oldspl = MUTEX_SPIN_OLDSPL(l->l_cpu); if (newl == NULL || newl->l_back == NULL) retval = cpu_switch(l, NULL); else { KASSERT(lwp_locked(newl, &sched_mutex)); remrunqueue(newl); cpu_switchto(l, newl); retval = 0; } /* * XXXSMP If we are using h/w performance counters, restore context. */ #if PERFCTRS if (PMC_ENABLED(l->l_proc)) { pmc_restore_context(l->l_proc); } #endif /* * We're running again; record our new start time. We might * be running on a new CPU now, so don't use the cached * schedstate_percpu pointer. */ SYSCALL_TIME_WAKEUP(l); KDASSERT(l->l_cpu == curcpu()); microtime(&l->l_cpu->ci_schedstate.spc_runtime); splx(oldspl); return retval; } /* * Initialize the (doubly-linked) run queues * to be empty. */ void rqinit() { int i; for (i = 0; i < RUNQUE_NQS; i++) sched_qs[i].ph_link = sched_qs[i].ph_rlink = (struct lwp *)&sched_qs[i]; mutex_init(&sched_mutex, MUTEX_SPIN, IPL_SCHED); } static inline void resched_lwp(struct lwp *l) { struct cpu_info *ci; const pri_t pri = lwp_eprio(l); /* * XXXSMP * Since l->l_cpu persists across a context switch, * this gives us *very weak* processor affinity, in * that we notify the CPU on which the process last * ran that it should try to switch. * * This does not guarantee that the process will run on * that processor next, because another processor might * grab it the next time it performs a context switch. * * This also does not handle the case where its last * CPU is running a higher-priority process, but every * other CPU is running a lower-priority process. There * are ways to handle this situation, but they're not * currently very pretty, and we also need to weigh the * cost of moving a process from one CPU to another. * * XXXSMP * There is also the issue of locking the other CPU's * sched state, which we currently do not do. */ ci = (l->l_cpu != NULL) ? l->l_cpu : curcpu(); if (pri < ci->ci_schedstate.spc_curpriority) cpu_need_resched(ci); } /* * 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. * * Call with the process and LWP locked. Will return with the LWP unlocked. */ void setrunnable(struct lwp *l) { struct proc *p = l->l_proc; sigset_t *ss; KASSERT(mutex_owned(&p->p_smutex)); KASSERT(lwp_locked(l, NULL)); switch (l->l_stat) { case LSSTOP: /* * If we're being traced (possibly because someone attached us * while we were stopped), check for a signal from the debugger. */ if ((p->p_slflag & PSL_TRACED) != 0 && p->p_xstat != 0) { if ((sigprop[p->p_xstat] & SA_TOLWP) != 0) ss = &l->l_sigpend.sp_set; else ss = &p->p_sigpend.sp_set; sigaddset(ss, p->p_xstat); signotify(l); } p->p_nrlwps++; break; case LSSUSPENDED: l->l_flag &= ~LW_WSUSPEND; p->p_nrlwps++; break; case LSSLEEP: KASSERT(l->l_wchan != NULL); break; default: panic("setrunnable: lwp %p state was %d", l, l->l_stat); } /* * If the LWP was sleeping interruptably, then it's OK to start it * again. If not, mark it as still sleeping. */ if (l->l_wchan != NULL) { l->l_stat = LSSLEEP; /* lwp_unsleep() will release the lock. */ lwp_unsleep(l); return; } LOCK_ASSERT(lwp_locked(l, &sched_mutex)); /* * If the LWP is still on the CPU, mark it as LSONPROC. It may be * about to call mi_switch(), in which case it will yield. * * XXXSMP Will need to change for preemption. */ #ifdef MULTIPROCESSOR if (l->l_cpu->ci_curlwp == l) { #else if (l == curlwp) { #endif l->l_stat = LSONPROC; l->l_slptime = 0; lwp_unlock(l); return; } /* * Set the LWP runnable. If it's swapped out, we need to wake the swapper * to bring it back in. Otherwise, enter it into a run queue. */ if (l->l_slptime > 1) updatepri(l); l->l_stat = LSRUN; l->l_slptime = 0; if (l->l_flag & LW_INMEM) { setrunqueue(l); resched_lwp(l); lwp_unlock(l); } else { lwp_unlock(l); uvm_kick_scheduler(); } } /* * 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 lwp *l) { pri_t newpriority; struct proc *p = l->l_proc; /* XXXSMP LOCK_ASSERT(mutex_owned(&p->p_stmutex)); */ LOCK_ASSERT(lwp_locked(l, NULL)); if ((l->l_flag & LW_SYSTEM) != 0) return; newpriority = PUSER + (p->p_estcpu >> ESTCPU_SHIFT) + NICE_WEIGHT * (p->p_nice - NZERO); newpriority = min(newpriority, MAXPRI); lwp_changepri(l, newpriority); } /* * Recompute priority for all LWPs in a process. */ void resetprocpriority(struct proc *p) { struct lwp *l; LOCK_ASSERT(mutex_owned(&p->p_stmutex)); LIST_FOREACH(l, &p->p_lwps, l_sibling) { lwp_lock(l); resetpriority(l); lwp_unlock(l); } } /* * 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. The formula for computing priorities (in kern_synch.c) * will compute a different value each time p_estcpu increases. This can * cause a switch, but unless the priority crosses a PPQ boundary the actual * queue will not change. 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(struct lwp *l) { struct proc *p = l->l_proc; mutex_spin_enter(&p->p_stmutex); p->p_estcpu = ESTCPULIM(p->p_estcpu + (1 << ESTCPU_SHIFT)); lwp_lock(l); resetpriority(l); mutex_spin_exit(&p->p_stmutex); if ((l->l_flag & LW_SYSTEM) == 0 && l->l_priority >= PUSER) l->l_priority = l->l_usrpri; lwp_unlock(l); } /* * suspendsched: * * Convert all non-L_SYSTEM LSSLEEP or LSRUN LWPs to LSSUSPENDED. */ void suspendsched(void) { #ifdef MULTIPROCESSOR CPU_INFO_ITERATOR cii; struct cpu_info *ci; #endif struct lwp *l; struct proc *p; /* * We do this by process in order not to violate the locking rules. */ mutex_enter(&proclist_mutex); PROCLIST_FOREACH(p, &allproc) { mutex_enter(&p->p_smutex); if ((p->p_flag & PK_SYSTEM) != 0) { mutex_exit(&p->p_smutex); continue; } p->p_stat = SSTOP; LIST_FOREACH(l, &p->p_lwps, l_sibling) { if (l == curlwp) continue; lwp_lock(l); /* * Set L_WREBOOT so that the LWP will suspend itself * when it tries to return to user mode. We want to * try and get to get as many LWPs as possible to * the user / kernel boundary, so that they will * release any locks that they hold. */ l->l_flag |= (LW_WREBOOT | LW_WSUSPEND); if (l->l_stat == LSSLEEP && (l->l_flag & LW_SINTR) != 0) { /* setrunnable() will release the lock. */ setrunnable(l); continue; } lwp_unlock(l); } mutex_exit(&p->p_smutex); } mutex_exit(&proclist_mutex); /* * Kick all CPUs to make them preempt any LWPs running in user mode. * They'll trap into the kernel and suspend themselves in userret(). */ sched_lock(0); #ifdef MULTIPROCESSOR for (CPU_INFO_FOREACH(cii, ci)) cpu_need_resched(ci); #else cpu_need_resched(curcpu()); #endif sched_unlock(0); } /* * scheduler_fork_hook: * * Inherit the parent's scheduler history. */ void scheduler_fork_hook(struct proc *parent, struct proc *child) { LOCK_ASSERT(mutex_owned(&parent->p_smutex)); child->p_estcpu = child->p_estcpu_inherited = parent->p_estcpu; child->p_forktime = schedcpu_ticks; } /* * scheduler_wait_hook: * * Chargeback parents for the sins of their children. */ void scheduler_wait_hook(struct proc *parent, struct proc *child) { fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); fixpt_t estcpu; /* XXX Only if parent != init?? */ mutex_spin_enter(&parent->p_stmutex); estcpu = decay_cpu_batch(loadfac, child->p_estcpu_inherited, schedcpu_ticks - child->p_forktime); if (child->p_estcpu > estcpu) parent->p_estcpu = ESTCPULIM(parent->p_estcpu + child->p_estcpu - estcpu); mutex_spin_exit(&parent->p_stmutex); } /* * sched_kpri: * * Scale a priority level to a kernel priority level, usually * for an LWP that is about to sleep. */ pri_t sched_kpri(struct lwp *l) { /* * Scale user priorities (127 -> 50) up to kernel priorities * in the range (49 -> 8). Reserve the top 8 kernel priorities * for high priority kthreads. Kernel priorities passed in * are left "as is". XXX This is somewhat arbitrary. */ static const uint8_t kpri_tab[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 14, 14, 15, 15, 16, 16, 17, 17, 18, 18, 19, 20, 20, 21, 21, 22, 22, 23, 23, 24, 24, 25, 26, 26, 27, 27, 28, 28, 29, 29, 30, 30, 31, 32, 32, 33, 33, 34, 34, 35, 35, 36, 36, 37, 38, 38, 39, 39, 40, 40, 41, 41, 42, 42, 43, 44, 44, 45, 45, 46, 46, 47, 47, 48, 48, 49, 49, }; return (pri_t)kpri_tab[l->l_usrpri]; } /* * sched_unsleep: * * The is called when the LWP has not been awoken normally but instead * interrupted: for example, if the sleep timed out. Because of this, * it's not a valid action for running or idle LWPs. */ void sched_unsleep(struct lwp *l) { lwp_unlock(l); panic("sched_unsleep"); } /* * sched_changepri: * * Adjust the priority of an LWP. */ void sched_changepri(struct lwp *l, pri_t pri) { LOCK_ASSERT(lwp_locked(l, &sched_mutex)); l->l_usrpri = pri; if (l->l_priority < PUSER) return; if (l->l_stat != LSRUN || (l->l_flag & LW_INMEM) == 0) { l->l_priority = pri; return; } remrunqueue(l); l->l_priority = pri; setrunqueue(l); resched_lwp(l); } void sched_lendpri(struct lwp *l, pri_t pri) { LOCK_ASSERT(lwp_locked(l, &sched_mutex)); if (l->l_stat != LSRUN || (l->l_flag & LW_INMEM) == 0) { l->l_inheritedprio = pri; return; } remrunqueue(l); l->l_inheritedprio = pri; setrunqueue(l); resched_lwp(l); } struct lwp * syncobj_noowner(wchan_t wchan) { return NULL; } /* * Low-level routines to access the run queue. Optimised assembler * routines can override these. */ #ifndef __HAVE_MD_RUNQUEUE /* * On some architectures, it's faster to use a MSB ordering for the priorites * than the traditional LSB ordering. */ #ifdef __HAVE_BIGENDIAN_BITOPS #define RQMASK(n) (0x80000000 >> (n)) #else #define RQMASK(n) (0x00000001 << (n)) #endif /* * The primitives that manipulate the run queues. whichqs tells which * of the 32 queues qs have processes in them. Setrunqueue puts processes * into queues, remrunqueue removes them from queues. The running process is * on no queue, other processes are on a queue related to p->p_priority, * divided by 4 actually to shrink the 0-127 range of priorities into the 32 * available queues. */ #ifdef RQDEBUG static void checkrunqueue(int whichq, struct lwp *l) { const struct prochd * const rq = &sched_qs[whichq]; struct lwp *l2; int found = 0; int die = 0; int empty = 1; for (l2 = rq->ph_link; l2 != (const void*) rq; l2 = l2->l_forw) { if (l2->l_stat != LSRUN) { printf("checkrunqueue[%d]: lwp %p state (%d) " " != LSRUN\n", whichq, l2, l2->l_stat); } if (l2->l_back->l_forw != l2) { printf("checkrunqueue[%d]: lwp %p back-qptr (%p) " "corrupt %p\n", whichq, l2, l2->l_back, l2->l_back->l_forw); die = 1; } if (l2->l_forw->l_back != l2) { printf("checkrunqueue[%d]: lwp %p forw-qptr (%p) " "corrupt %p\n", whichq, l2, l2->l_forw, l2->l_forw->l_back); die = 1; } if (l2 == l) found = 1; empty = 0; } if (empty && (sched_whichqs & RQMASK(whichq)) != 0) { printf("checkrunqueue[%d]: bit set for empty run-queue %p\n", whichq, rq); die = 1; } else if (!empty && (sched_whichqs & RQMASK(whichq)) == 0) { printf("checkrunqueue[%d]: bit clear for non-empty " "run-queue %p\n", whichq, rq); die = 1; } if (l != NULL && (sched_whichqs & RQMASK(whichq)) == 0) { printf("checkrunqueue[%d]: bit clear for active lwp %p\n", whichq, l); die = 1; } if (l != NULL && empty) { printf("checkrunqueue[%d]: empty run-queue %p with " "active lwp %p\n", whichq, rq, l); die = 1; } if (l != NULL && !found) { printf("checkrunqueue[%d]: lwp %p not in runqueue %p!", whichq, l, rq); die = 1; } if (die) panic("checkrunqueue: inconsistency found"); } #endif /* RQDEBUG */ void setrunqueue(struct lwp *l) { struct prochd *rq; struct lwp *prev; const int whichq = lwp_eprio(l) / PPQ; LOCK_ASSERT(lwp_locked(l, &sched_mutex)); #ifdef RQDEBUG checkrunqueue(whichq, NULL); #endif #ifdef DIAGNOSTIC if (l->l_back != NULL || l->l_stat != LSRUN) panic("setrunqueue"); #endif sched_whichqs |= RQMASK(whichq); rq = &sched_qs[whichq]; prev = rq->ph_rlink; l->l_forw = (struct lwp *)rq; rq->ph_rlink = l; prev->l_forw = l; l->l_back = prev; #ifdef RQDEBUG checkrunqueue(whichq, l); #endif } /* * XXXSMP When LWP dispatch (cpu_switch()) is changed to use remrunqueue(), * drop of the effective priority level from kernel to user needs to be * moved here from userret(). The assignment in userret() is currently * done unlocked. */ void remrunqueue(struct lwp *l) { struct lwp *prev, *next; const int whichq = lwp_eprio(l) / PPQ; LOCK_ASSERT(lwp_locked(l, &sched_mutex)); #ifdef RQDEBUG checkrunqueue(whichq, l); #endif #if defined(DIAGNOSTIC) if (((sched_whichqs & RQMASK(whichq)) == 0) || l->l_back == NULL) { /* Shouldn't happen - interrupts disabled. */ panic("remrunqueue: bit %d not set", whichq); } #endif prev = l->l_back; l->l_back = NULL; next = l->l_forw; prev->l_forw = next; next->l_back = prev; if (prev == next) sched_whichqs &= ~RQMASK(whichq); #ifdef RQDEBUG checkrunqueue(whichq, NULL); #endif } #undef RQMASK #endif /* !defined(__HAVE_MD_RUNQUEUE) */