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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2009-01-28 14:51:40 +0100
committerIngo Molnar <mingo@elte.hu>2009-02-01 10:49:51 +0100
commita571bbeafbcc501d9989fbce1cddcd810bd51d71 (patch)
treecbfc71ece2ae3e351424d5f7ca9d8fff2429827b
parentsched: clear buddies more aggressively (diff)
downloadlinux-a571bbeafbcc501d9989fbce1cddcd810bd51d71.tar.xz
linux-a571bbeafbcc501d9989fbce1cddcd810bd51d71.zip
sched: fix buddie group latency
Similar to the previous patch, by not clearing buddies we can select entities past their run quota, which can increase latency. This means we have to clear group buddies as well. Do not use the group clear for pick_next_task(), otherwise that'll get O(n^2). Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/sched_fair.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 75248b9ff4c1..a7e50ba185ac 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -719,7 +719,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
__enqueue_entity(cfs_rq, se);
}
-static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
+static void __clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
if (cfs_rq->last == se)
cfs_rq->last = NULL;
@@ -728,6 +728,12 @@ static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
cfs_rq->next = NULL;
}
+static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+ for_each_sched_entity(se)
+ __clear_buddies(cfs_rq_of(se), se);
+}
+
static void
dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
{
@@ -1455,7 +1461,7 @@ static struct task_struct *pick_next_task_fair(struct rq *rq)
* If se was a buddy, clear it so that it will have to earn
* the favour again.
*/
- clear_buddies(cfs_rq, se);
+ __clear_buddies(cfs_rq, se);
set_next_entity(cfs_rq, se);
cfs_rq = group_cfs_rq(se);
} while (cfs_rq);