tree 4565659d1084e357eea42e6321a4d304ac950faa
parent 09b22a2f678ae733801b888c44756d0abd686b8a
author Peter Zijlstra <a.p.zijlstra@chello.nl> 1221946682 +0200
committer Ingo Molnar <mingo@elte.hu> 1222093712 +0200

sched: wakeup preempt when small overlap

Lin Ming reported a 10% OLTP regression against 2.6.27-rc4.

The difference seems to come from different preemption agressiveness,
which affects the cache footprint of the workload and its effective
cache trashing.

Aggresively preempt a task if its avg overlap is very small, this should
avoid the task going to sleep and find it still running when we schedule
back to it - saving a wakeup.

Reported-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>