If the previous CPU is cache affine and idle, select it.
Signed-off-by: Mike Galbraith <bitbuc...@online.de>
---
kernel/sched/fair.c | 21 +++++++--------------
1 file changed, 7 insertions(+), 14 deletions(-)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3270,25 +3270,18 @@ find_idlest_cpu(struct sched_group *grou
*/
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;
struct sched_group *sg;
- int i;
+ int i = task_cpu(p);
- /*
- * 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 && idle_cpu(cpu))
- return cpu;
+ if (idle_cpu(target))
+ return target;
/*
- * 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 the prevous cpu is cache affine and idle, don't be stupid.
*/
- if (target == prev_cpu && idle_cpu(prev_cpu))
- return prev_cpu;
+ if (i != target && cpus_share_cache(i, target) && idle_cpu(i))
+ return i;
/*
* Otherwise, iterate the domains and find an elegible idle cpu.
@@ -3302,7 +3295,7 @@ static int select_idle_sibling(struct ta
goto next;
for_each_cpu(i, sched_group_cpus(sg)) {
- if (!idle_cpu(i))
+ if (i == target || !idle_cpu(i))
goto next;
}
--
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