Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=296825...
Commit: 296825cbe14d4c95ee9c41ca5824f7487bfb4d9d
Parent: 095031052b4c03a7c8ffa51cbab031e442c4f8b7
Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
AuthorDate: Thu Jan 31 22:45:22 2008 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu Jan 31 22:45:22 2008 +0100
sched: fix high wake up latencies with FAIR_USER_SCHED
The reason why we are getting better wakeup latencies for
!FAIR_USER_SCHED is because of this snippet of code in place_entity():
if (!initial) {
/* sleeps upto a single latency don't count. */
if (sched_feat(NEW_FAIR_SLEEPERS) && entity_is_task(se))
^^^^^^^^^^^^^^^^^^
vruntime -= sysctl_sched_latency;
/* ensure we never gain time by being placed backwards. */
vruntime = max_vruntime(se->vruntime, vruntime);
}
NEW_FAIR_SLEEPERS feature gives credit for sleeping only to tasks and
not group-level entities. With the patch attached, I could see that
wakeup latencies with FAIR_USER_SCHED are restored to the same level as
!FAIR_USER_SCHED.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/sched_fair.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 72e25c7..cf958ae 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -520,7 +520,7 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
if (!initial) {
/* sleeps upto a single latency don't count. */
- if (sched_feat(NEW_FAIR_SLEEPERS) && entity_is_task(se))
+ if (sched_feat(NEW_FAIR_SLEEPERS))
vruntime -= sysctl_sched_latency;
/* ensure we never gain time by being placed backwards. */
-
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