2.6.32-longterm review patch. If anyone has any objections, please let me know.
------------------
From: Mike Galbraith <efa...@gmx.de>
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 <ve...@google.com>
Signed-off-by: Mike Galbraith <efa...@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijls...@chello.nl>
LKML-Reference: <1294202477.9384.5.ca...@marge.simson.net>
Signed-off-by: Ingo Molnar <mi...@elte.hu>
Signed-off-by: Willy Tarreau <w...@1wt.eu>
---
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 cd9a40b..fd6e5f2 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);
}
--
1.7.2.1.45.g54fbc
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