diff options
| author | Mike Galbraith <efault@gmx.de> | 2011-01-05 05:41:17 +0100 |
|---|---|---|
| committer | Willy Tarreau <w@1wt.eu> | 2012-10-07 23:37:17 +0200 |
| commit | 2c224ae6d1be39d99ea53fa9acd47bec111dbd68 (patch) | |
| tree | 00a9754fcf6e30278effcf98fb1746ebdc54b29a /kernel | |
| parent | 0b65cf58957e0b6ca52143430871077e24868c6c (diff) | |
sched: Fix signed unsigned comparison in check_preempt_tick()
commit d7d8294415f0ce4254827d4a2a5ee88b00be52a8 upstream.
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>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched_fair.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index cd9a40b5d50..fd6e5f2a160 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -862,6 +862,9 @@ 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); } |