Module Name: src
Committed By: ad
Date: Fri Dec 6 18:33:19 UTC 2019
Modified Files:
src/sys/kern: sched_4bsd.c sched_m2.c
Log Message:
sched_tick(): don't try to optimise something that's called 10 times a
second, it's a fine way to introduce bugs (and I did). Use the MI
interface for rescheduling which always does the correct thing.
To generate a diff of this commit:
cvs rdiff -u -r1.40 -r1.41 src/sys/kern/sched_4bsd.c
cvs rdiff -u -r1.36 -r1.37 src/sys/kern/sched_m2.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/sched_4bsd.c
diff -u src/sys/kern/sched_4bsd.c:1.40 src/sys/kern/sched_4bsd.c:1.41
--- src/sys/kern/sched_4bsd.c:1.40 Sun Dec 1 15:34:46 2019
+++ src/sys/kern/sched_4bsd.c Fri Dec 6 18:33:19 2019
@@ -1,4 +1,4 @@
-/* $NetBSD: sched_4bsd.c,v 1.40 2019/12/01 15:34:46 ad Exp $ */
+/* $NetBSD: sched_4bsd.c,v 1.41 2019/12/06 18:33:19 ad Exp $ */
/*
* Copyright (c) 1999, 2000, 2004, 2006, 2007, 2008, 2019
@@ -69,7 +69,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sched_4bsd.c,v 1.40 2019/12/01 15:34:46 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sched_4bsd.c,v 1.41 2019/12/06 18:33:19 ad Exp $");
#include "opt_ddb.h"
#include "opt_lockdebug.h"
@@ -104,13 +104,15 @@ void
sched_tick(struct cpu_info *ci)
{
struct schedstate_percpu *spc = &ci->ci_schedstate;
+ pri_t pri = PRI_NONE;
lwp_t *l;
spc->spc_ticks = rrticks;
if (CURCPU_IDLE_P()) {
- atomic_or_uint(&ci->ci_want_resched,
- RESCHED_IDLE | RESCHED_UPREEMPT);
+ spc_lock(ci);
+ sched_resched_cpu(ci, MAXPRI_KTHREAD, true);
+ /* spc now unlocked */
return;
}
l = ci->ci_onproc;
@@ -128,12 +130,7 @@ sched_tick(struct cpu_info *ci)
break;
case SCHED_RR:
/* Force it into mi_switch() to look for other jobs to run. */
-#ifdef __HAVE_PREEMPTION
- atomic_or_uint(&l->l_dopreempt, DOPREEMPT_ACTIVE);
- atomic_or_uint(&ci->ci_want_resched, RESCHED_KPREEMPT);
-#else
- atomic_or_uint(&ci->ci_want_resched, RESCHED_UPREEMPT);
-#endif
+ pri = MAXPRI_KERNEL_RT;
break;
default:
if (spc->spc_flags & SPCF_SHOULDYIELD) {
@@ -142,25 +139,25 @@ sched_tick(struct cpu_info *ci)
* due to buggy or inefficient code. Force a
* kernel preemption.
*/
-#ifdef __HAVE_PREEMPTION
- atomic_or_uint(&l->l_dopreempt, DOPREEMPT_ACTIVE);
- atomic_or_uint(&ci->ci_want_resched, RESCHED_KPREEMPT);
-#else
- atomic_or_uint(&ci->ci_want_resched, RESCHED_UPREEMPT);
-#endif
+ pri = MAXPRI_KERNEL_RT;
} else 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;
- atomic_or_uint(&ci->ci_want_resched, RESCHED_UPREEMPT);
+ pri = MAXPRI_KTHREAD;
} else {
spc->spc_flags |= SPCF_SEENRR;
}
break;
}
+
+ if (pri != PRI_NONE) {
+ spc_lock(ci);
+ sched_resched_cpu(ci, pri, true);
+ /* spc now unlocked */
+ }
}
/*
Index: src/sys/kern/sched_m2.c
diff -u src/sys/kern/sched_m2.c:1.36 src/sys/kern/sched_m2.c:1.37
--- src/sys/kern/sched_m2.c:1.36 Sun Dec 1 15:34:46 2019
+++ src/sys/kern/sched_m2.c Fri Dec 6 18:33:19 2019
@@ -1,4 +1,4 @@
-/* $NetBSD: sched_m2.c,v 1.36 2019/12/01 15:34:46 ad Exp $ */
+/* $NetBSD: sched_m2.c,v 1.37 2019/12/06 18:33:19 ad Exp $ */
/*
* Copyright (c) 2007, 2008 Mindaugas Rasiukevicius <rmind at NetBSD org>
@@ -33,7 +33,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sched_m2.c,v 1.36 2019/12/01 15:34:46 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sched_m2.c,v 1.37 2019/12/06 18:33:19 ad Exp $");
#include <sys/param.h>
@@ -330,7 +330,9 @@ sched_tick(struct cpu_info *ci)
*/
if (lwp_eprio(l) <= spc->spc_maxpriority || l->l_target_cpu) {
spc->spc_flags |= SPCF_SHOULDYIELD;
- atomic_or_uint(&ci->ci_want_resched, RESCHED_UPREEMPT);
+ spc_lock(ci);
+ sched_resched_cpu(ci, MAXPRI_KTHREAD, true);
+ /* spc now unlocked */
} else
spc->spc_ticks = l->l_sched.timeslice;
lwp_unlock(l);
