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sched: Cleanup select_task_rq_fair()

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Clean up the new affine to idle sibling bits while trying to
grok them. Should not have any function differences.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20091112145610.832503781@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-11-12 15:55:28 +01:00 committed by Ingo Molnar
parent 761b1d26df
commit a50bde5130
1 changed files with 52 additions and 23 deletions
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75
kernel/sched_fair.c
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@ -1318,6 +1318,41 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
return idlest;
}
/*
* Try and locate an idle CPU in the sched_domain.
*/
static int
select_idle_sibling(struct task_struct *p, struct sched_domain *sd, int target)
{
int cpu = smp_processor_id();
int prev_cpu = task_cpu(p);
int i;
/*
* If this domain spans both cpu and prev_cpu (see the SD_WAKE_AFFINE
* test in select_task_rq_fair) and the prev_cpu is idle then that's
* always a better target than the current cpu.
*/
if (target == cpu) {
if (!cpu_rq(prev_cpu)->cfs.nr_running)
target = prev_cpu;
}
/*
* Otherwise, iterate the domain and find an elegible idle cpu.
*/
if (target == -1 || target == cpu) {
for_each_cpu_and(i, sched_domain_span(sd), &p->cpus_allowed) {
if (!cpu_rq(i)->cfs.nr_running) {
target = i;
break;
}
}
}
return target;
}
/*
* sched_balance_self: balance the current task (running on cpu) in domains
* that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
@ -1373,36 +1408,30 @@ static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flag
}
if (want_affine && (tmp->flags & SD_WAKE_AFFINE)) {
int candidate = -1, i;
if (cpumask_test_cpu(prev_cpu, sched_domain_span(tmp)))
candidate = cpu;
int target = -1;
/*
* Check for an idle shared cache.
* If both cpu and prev_cpu are part of this domain,
* cpu is a valid SD_WAKE_AFFINE target.
*/
if (tmp->flags & SD_PREFER_SIBLING) {
if (candidate == cpu) {
if (!cpu_rq(prev_cpu)->cfs.nr_running)
candidate = prev_cpu;
}
if (cpumask_test_cpu(prev_cpu, sched_domain_span(tmp)))
target = cpu;
if (candidate == -1 || candidate == cpu) {
for_each_cpu(i, sched_domain_span(tmp)) {
if (!cpumask_test_cpu(i, &p->cpus_allowed))
continue;
if (!cpu_rq(i)->cfs.nr_running) {
candidate = i;
break;
}
}
}
}
/*
* If there's an idle sibling in this domain, make that
* the wake_affine target instead of the current cpu.
*
* XXX: should we possibly do this outside of
* WAKE_AFFINE, in case the shared cache domain is
* smaller than the WAKE_AFFINE domain?
*/
if (tmp->flags & SD_PREFER_SIBLING)
target = select_idle_sibling(p, tmp, target);
if (candidate >= 0) {
if (target >= 0) {
affine_sd = tmp;
want_affine = 0;
cpu = candidate;
cpu = target;
}
}