fix a long-standing scheduler problem that p_estcpu is doubled
for each fork-wait cycles. - updatepri: factor out the code to decay estcpu so that it can be used by scheduler_wait_hook. - scheduler_fork_hook: record how much estcpu is inherited from the parent process. - scheduler_wait_hook: don't add back inherited estcpu to the parent.
This commit is contained in:
yamt
parent
f37f56be99
commit
6454c469ea
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@ -1,4 +1,4 @@
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/* $NetBSD: kern_synch.c,v 1.156 2005/12/20 19:26:15 rpaulo Exp $ */
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/* $NetBSD: kern_synch.c,v 1.157 2005/12/24 12:57:14 yamt Exp $ */
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/*-
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* Copyright (c) 1999, 2000, 2004 The NetBSD Foundation, Inc.
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@ -76,7 +76,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: kern_synch.c,v 1.156 2005/12/20 19:26:15 rpaulo Exp $");
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__KERNEL_RCSID(0, "$NetBSD: kern_synch.c,v 1.157 2005/12/24 12:57:14 yamt Exp $");
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#include "opt_ddb.h"
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#include "opt_ktrace.h"
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@ -140,7 +140,7 @@ __inline void sa_awaken(struct lwp *);
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__inline void awaken(struct lwp *);
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struct callout schedcpu_ch = CALLOUT_INITIALIZER_SETFUNC(schedcpu, NULL);
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static unsigned int schedcpu_ticks;
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/*
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@ -262,6 +262,29 @@ decay_cpu(fixpt_t loadfac, fixpt_t estcpu)
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return (uint64_t)estcpu * loadfac / (loadfac + FSCALE);
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}
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/*
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* For all load averages >= 1 and max p_estcpu of (255 << ESTCPU_SHIFT),
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* sleeping for at least seven times the loadfactor will decay p_estcpu to
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* less than (1 << ESTCPU_SHIFT).
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*
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* note that our ESTCPU_MAX is actually much smaller than (255 << ESTCPU_SHIFT).
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*/
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static fixpt_t
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decay_cpu_batch(fixpt_t loadfac, fixpt_t estcpu, unsigned int n)
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{
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if ((n << FSHIFT) >= 7 * loadfac) {
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return 0;
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}
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while (estcpu != 0 && n > 1) {
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estcpu = decay_cpu(loadfac, estcpu);
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n--;
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}
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return estcpu;
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}
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/* decay 95% of `p_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */
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fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
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@ -292,6 +315,8 @@ schedcpu(void *arg)
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int s, minslp;
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int clkhz;
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schedcpu_ticks++;
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proclist_lock_read();
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PROCLIST_FOREACH(p, &allproc) {
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/*
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@ -359,32 +384,21 @@ schedcpu(void *arg)
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/*
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* Recalculate the priority of a process after it has slept for a while.
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* For all load averages >= 1 and max p_estcpu of (255 << ESTCPU_SHIFT),
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* sleeping for at least eight times the loadfactor will decay p_estcpu to
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* less than (1 << ESTCPU_SHIFT).
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*
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* note that our ESTCPU_MAX is actually much smaller than (255 << ESTCPU_SHIFT).
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*/
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void
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updatepri(struct lwp *l)
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{
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struct proc *p = l->l_proc;
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fixpt_t newcpu;
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fixpt_t loadfac;
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SCHED_ASSERT_LOCKED();
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KASSERT(l->l_slptime > 1);
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newcpu = p->p_estcpu;
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loadfac = loadfactor(averunnable.ldavg[0]);
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if ((l->l_slptime << FSHIFT) >= 8 * loadfac)
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p->p_estcpu = 0; /* XXX NJWLWP */
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else {
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l->l_slptime--; /* the first time was done in schedcpu */
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while (newcpu && --l->l_slptime)
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newcpu = decay_cpu(loadfac, newcpu);
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p->p_estcpu = newcpu;
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}
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l->l_slptime--; /* the first time was done in schedcpu */
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/* XXX NJWLWP */
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p->p_estcpu = decay_cpu_batch(loadfac, p->p_estcpu, l->l_slptime);
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resetpriority(l);
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}
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@ -1240,7 +1254,8 @@ void
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scheduler_fork_hook(struct proc *parent, struct proc *child)
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{
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child->p_estcpu = parent->p_estcpu;
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child->p_estcpu = child->p_estcpu_inherited = parent->p_estcpu;
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child->p_forktime = schedcpu_ticks;
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}
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/*
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@ -1251,9 +1266,17 @@ scheduler_fork_hook(struct proc *parent, struct proc *child)
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void
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scheduler_wait_hook(struct proc *parent, struct proc *child)
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{
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fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
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fixpt_t estcpu;
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/* XXX Only if parent != init?? */
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parent->p_estcpu = ESTCPULIM(parent->p_estcpu + child->p_estcpu);
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estcpu = decay_cpu_batch(loadfac, child->p_estcpu_inherited,
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schedcpu_ticks - child->p_forktime);
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if (child->p_estcpu > estcpu) {
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parent->p_estcpu =
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ESTCPULIM(parent->p_estcpu + child->p_estcpu - estcpu);
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}
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}
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/*
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@ -1,4 +1,4 @@
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/* $NetBSD: proc.h,v 1.209 2005/12/11 12:25:21 christos Exp $ */
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/* $NetBSD: proc.h,v 1.210 2005/12/24 12:57:14 yamt Exp $ */
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/*-
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* Copyright (c) 1986, 1989, 1991, 1993
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@ -202,6 +202,8 @@ struct proc {
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/* scheduling */
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fixpt_t p_estcpu; /* Time averaged value of p_cpticks XXX belongs in p_startcopy section */
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fixpt_t p_estcpu_inherited;
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unsigned int p_forktime;
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int p_cpticks; /* Ticks of CPU time */
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fixpt_t p_pctcpu; /* %cpu for this process during p_swtime */
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