Re: [tbench regression fixes]: digging out smelly deadmen.

David Miller
2008-10-26T03:55:35Z

From: "Rafael J. Wysocki" <rjw@sisk.pl>
Date: Sat, 25 Oct 2008 13:13:20 +0200

> Could you please give me a pointer to the commit disabling the hrtimer feature?

Here it is:

commit 0c4b83da58ec2e96ce9c44c211d6eac5f9dae478
Author: Ingo Molnar <mingo@elte.hu>
Date: Mon Oct 20 14:27:43 2008 +0200

sched: disable the hrtick for now

David Miller reported that hrtick update overhead has tripled the
wakeup overhead on Sparc64.

That is too much - disable the HRTICK feature for now by default,
until a faster implementation is found.

Reported-by: David Miller <davem@davemloft.net>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/sched_features.h b/kernel/sched_features.h
index 7c9e8f4..fda0162 100644
--- a/kernel/sched_features.h
+++ b/kernel/sched_features.h
@@ -5,7 +5,7 @@ SCHED_FEAT(START_DEBIT, 1)
SCHED_FEAT(AFFINE_WAKEUPS, 1)
SCHED_FEAT(CACHE_HOT_BUDDY, 1)
SCHED_FEAT(SYNC_WAKEUPS, 1)
-SCHED_FEAT(HRTICK, 1)
+SCHED_FEAT(HRTICK, 0)
SCHED_FEAT(DOUBLE_TICK, 0)
SCHED_FEAT(ASYM_GRAN, 1)
SCHED_FEAT(LB_BIAS, 1)