From: Peter Zijlstra <peterz@infradead.org>
To: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Mike Galbraith <efault@gmx.de>, Ingo Molnar <mingo@elte.hu>,
Arjan van de Ven <arjan@linux.jf.intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
Yanmin Zhang <yanmin_zhang@linux.jf.intel.com>,
Gautham R Shenoy <ego@in.ibm.com>
Subject: Re: [patch v2 1/2] sched: check for prev_cpu == this_cpu before calling wake_affine()
Date: Tue, 20 Apr 2010 10:55:06 +0200 [thread overview]
Message-ID: <1271753706.1676.402.camel@laptop> (raw)
In-Reply-To: <1271753212.1676.400.camel@laptop>
On Tue, 2010-04-20 at 10:46 +0200, Peter Zijlstra wrote:
> So should we be using idle_cpu(i) instead?
something like the below..
---
Index: linux-2.6/kernel/sched_fair.c
===================================================================
--- linux-2.6.orig/kernel/sched_fair.c
+++ linux-2.6/kernel/sched_fair.c
@@ -1375,26 +1375,25 @@ find_idlest_cpu(struct sched_group *grou
/*
* Try and locate an idle CPU in the sched_domain.
*/
-static int
-select_idle_sibling(struct task_struct *p, int target)
+static int select_idle_sibling(struct task_struct *p, int target)
{
int cpu = smp_processor_id();
int prev_cpu = task_cpu(p);
- int i;
struct sched_domain *sd;
+ int i;
/*
* If the task is going to be woken-up on this cpu and if it is
* already idle, then it is the right target.
*/
- if (target == cpu && !cpu_rq(cpu)->cfs.nr_running)
+ if (target == cpu && idle_cpu(cpu))
return cpu;
/*
* If the task is going to be woken-up on the cpu where it previously
* ran and if it is currently idle, then it the right target.
*/
- if (target == prev_cpu && !cpu_rq(prev_cpu)->cfs.nr_running)
+ if (target == prev_cpu && idle_cpu(prev_cpu))
return prev_cpu;
/*
@@ -1405,7 +1404,7 @@ select_idle_sibling(struct task_struct *
break;
for_each_cpu_and(i, sched_domain_span(sd), &p->cpus_allowed) {
- if (!cpu_rq(i)->cfs.nr_running) {
+ if (idle_cpu(i)) {
target = i;
break;
}
@@ -1479,16 +1478,14 @@ select_task_rq_fair(struct rq *rq, struc
want_sd = 0;
}
- if (want_affine) {
- /*
- * If both cpu and prev_cpu are part of this domain,
- * cpu is a valid SD_WAKE_AFFINE target.
- */
- if (cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))
- && (tmp->flags & SD_WAKE_AFFINE)) {
- affine_sd = tmp;
- want_affine = 0;
- }
+ /*
+ * If both cpu and prev_cpu are part of this domain,
+ * cpu is a valid SD_WAKE_AFFINE target.
+ */
+ if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
+ cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
+ affine_sd = tmp;
+ want_affine = 0;
}
if (!want_sd && !want_affine)
next prev parent reply other threads:[~2010-04-20 8:55 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-08 22:19 [patch v2 1/2] sched: check for prev_cpu == this_cpu before calling wake_affine() Suresh Siddha
2010-03-08 22:19 ` [patch v2 2/2] sched: fix select_idle_sibling() logic in select_task_rq_fair() Suresh Siddha
2010-03-31 10:25 ` [patch v2 1/2] sched: check for prev_cpu == this_cpu before calling wake_affine() Peter Zijlstra
2010-03-31 23:47 ` Suresh Siddha
2010-04-01 5:32 ` Mike Galbraith
2010-04-01 21:04 ` Suresh Siddha
2010-04-02 6:20 ` Mike Galbraith
2010-04-02 17:05 ` Suresh Siddha
2010-04-02 19:43 ` Mike Galbraith
2010-04-14 20:45 ` Suresh Siddha
2010-04-15 5:17 ` Mike Galbraith
2010-04-20 8:46 ` Peter Zijlstra
2010-04-20 8:55 ` Peter Zijlstra [this message]
2010-04-20 17:03 ` Suresh Siddha
2010-04-23 10:50 ` [tip:sched/core] sched: Fix select_idle_sibling() logic in select_task_rq_fair() tip-bot for Suresh Siddha
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