sched: Avoid SMT siblings in select_idle_sibling() if possible
Avoid select_idle_sibling() from picking a sibling thread if there's an idle core that shares cache. This fixes SMT balancing in the increasingly common case where there's a shared cache core available to balance to. Tested-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Link: http://lkml.kernel.org/r/1321350377.1421.55.camel@twins Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
parent
f1c6f1a7ee
commit
4dcfe1025b
|
@ -2326,7 +2326,8 @@ static int select_idle_sibling(struct task_struct *p, int target)
|
|||
int cpu = smp_processor_id();
|
||||
int prev_cpu = task_cpu(p);
|
||||
struct sched_domain *sd;
|
||||
int i;
|
||||
struct sched_group *sg;
|
||||
int i, smt = 0;
|
||||
|
||||
/*
|
||||
* If the task is going to be woken-up on this cpu and if it is
|
||||
|
@ -2346,25 +2347,38 @@ static int select_idle_sibling(struct task_struct *p, int target)
|
|||
* Otherwise, iterate the domains and find an elegible idle cpu.
|
||||
*/
|
||||
rcu_read_lock();
|
||||
again:
|
||||
for_each_domain(target, sd) {
|
||||
if (!(sd->flags & SD_SHARE_PKG_RESOURCES))
|
||||
break;
|
||||
if (!smt && (sd->flags & SD_SHARE_CPUPOWER))
|
||||
continue;
|
||||
|
||||
for_each_cpu_and(i, sched_domain_span(sd), tsk_cpus_allowed(p)) {
|
||||
if (idle_cpu(i)) {
|
||||
target = i;
|
||||
break;
|
||||
if (!(sd->flags & SD_SHARE_PKG_RESOURCES)) {
|
||||
if (!smt) {
|
||||
smt = 1;
|
||||
goto again;
|
||||
}
|
||||
break;
|
||||
}
|
||||
|
||||
/*
|
||||
* Lets stop looking for an idle sibling when we reached
|
||||
* the domain that spans the current cpu and prev_cpu.
|
||||
*/
|
||||
if (cpumask_test_cpu(cpu, sched_domain_span(sd)) &&
|
||||
cpumask_test_cpu(prev_cpu, sched_domain_span(sd)))
|
||||
break;
|
||||
sg = sd->groups;
|
||||
do {
|
||||
if (!cpumask_intersects(sched_group_cpus(sg),
|
||||
tsk_cpus_allowed(p)))
|
||||
goto next;
|
||||
|
||||
for_each_cpu(i, sched_group_cpus(sg)) {
|
||||
if (!idle_cpu(i))
|
||||
goto next;
|
||||
}
|
||||
|
||||
target = cpumask_first_and(sched_group_cpus(sg),
|
||||
tsk_cpus_allowed(p));
|
||||
goto done;
|
||||
next:
|
||||
sg = sg->next;
|
||||
} while (sg != sd->groups);
|
||||
}
|
||||
done:
|
||||
rcu_read_unlock();
|
||||
|
||||
return target;
|
||||
|
|
Loading…
Reference in a new issue