sched: Stop buddies from hogging the system
authorPeter Zijlstra <a.p.zijlstra@chello.nl>
Thu, 17 Sep 2009 07:01:20 +0000 (09:01 +0200)
committerIngo Molnar <mingo@elte.hu>
Thu, 17 Sep 2009 08:40:30 +0000 (10:40 +0200)
commitde69a80be32445b0a71e8e3b757e584d7beb90f7
tree3a8d6bf8e5aded3c371e5dc090b8874305952d1f
parentad4b78bbcbab66998b05d422ac6106b645796e54
sched: Stop buddies from hogging the system

Clear buddies more agressively.

The (theoretical, haven't actually observed any of this) problem is
that when we do not select either buddy in pick_next_entity()
because they are too far ahead of the left-most task, we do not
clear the buddies.

This means that as soon as we service the left-most task, these
same buddies will be tried again on the next schedule. Now if the
left-most task was a pure hog, it wouldn't have done any wakeups
and it wouldn't have set buddies of its own. That leads to the old
buddies dominating, which would lead to bad latencies.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
kernel/sched_fair.c