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authorMike Galbraith <efault@gmx.de>2008-08-11 13:32:02 +0200
committerIngo Molnar <mingo@elte.hu>2008-08-11 14:49:29 +0200
commit77ae651347bdd46830da8b28b1efc5e4a9d7cbd0 (patch)
tree5c43252b5811cc0cba7b92e6b2fd241e0df6e3c8 /kernel
parent251a169c69d1ff07cee7a9bb9fc4faff6b1d2ac3 (diff)
sched: fix mysql+oltp regression
Defer commit 6d299f1b53b84e2665f402d9bcc494800aba6386 to the next release. Testing of the tip/sched/clock tree revealed a mysql+oltp regression which bisection eventually traced back to this commit in mainline. Pertinent test results: Three run sysbench averages, throughput units in read/write requests/sec. clients 1 2 4 8 16 32 64 6e0534f 9646 17876 34774 33868 32230 30767 29441 2.6.26.1 9112 17936 34652 33383 31929 30665 29232 6d299f1 9112 14637 28370 33339 32038 30762 29204 Note: subsequent commits hide the majority of this regression until you apply the clock fixes, at which time it reemerges at full magnitude. We cannot see anything bad about the change itself so we defer it to the next release until this problem is fully analysed. Signed-off-by: Mike Galbraith <efault@gmx.de> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Gregory Haskins <ghaskins@novell.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched_fair.c19
1 files changed, 12 insertions, 7 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 0fe94ea43f32..fb8994c6d4bb 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1442,18 +1442,23 @@ __load_balance_iterator(struct cfs_rq *cfs_rq, struct list_head *next)
struct task_struct *p = NULL;
struct sched_entity *se;
- while (next != &cfs_rq->tasks) {
+ if (next == &cfs_rq->tasks)
+ return NULL;
+
+ /* Skip over entities that are not tasks */
+ do {
se = list_entry(next, struct sched_entity, group_node);
next = next->next;
+ } while (next != &cfs_rq->tasks && !entity_is_task(se));
- /* Skip over entities that are not tasks */
- if (entity_is_task(se)) {
- p = task_of(se);
- break;
- }
- }
+ if (next == &cfs_rq->tasks)
+ return NULL;
cfs_rq->balance_iterator = next;
+
+ if (entity_is_task(se))
+ p = task_of(se);
+
return p;
}

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