aboutsummaryrefslogtreecommitdiff
path: root/kernel
diff options
context:
space:
mode:
authorMike Galbraith <efault@gmx.de>2011-01-05 05:41:17 +0100
committerIngo Molnar <mingo@elte.hu>2011-01-18 15:09:44 +0100
commitd7d8294415f0ce4254827d4a2a5ee88b00be52a8 (patch)
tree9f8024d6566bc391fcb2aced8427db81ca4e9078 /kernel
parentfce2097983d914ea8c2338efc6f6e9bb737f6ae4 (diff)
downloadlinux-linaro-precise-d7d8294415f0ce4254827d4a2a5ee88b00be52a8.tar.gz
sched: Fix signed unsigned comparison in check_preempt_tick()
Signed unsigned comparison may lead to superfluous resched if leftmost is right of the current task, wasting a few cycles, and inadvertently _lengthening_ the current task's slice. Reported-by: Venkatesh Pallipadi <venki@google.com> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1294202477.9384.5.camel@marge.simson.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched_fair.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 414145cf534..77e9166d7bb 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1062,6 +1062,9 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
struct sched_entity *se = __pick_next_entity(cfs_rq);
s64 delta = curr->vruntime - se->vruntime;
+ if (delta < 0)
+ return;
+
if (delta > ideal_runtime)
resched_task(rq_of(cfs_rq)->curr);
}