tree d63d707ee5b9d1dbc8e5796e142ca584736f01b9
parent 8ae121ac8666b0421aa20fd80d4597ec66fa54bc
author Gregory Haskins <ghaskins@novell.com> 1209400801 -0400
committer Ingo Molnar <mingo@elte.hu> 1210024578 +0200

sched: fix SCHED_FAIR wake-idle logic error

We currently use an optimization to skip the overhead of wake-idle
processing if more than one task is assigned to a run-queue.  The
assumption is that the system must already be load-balanced or we
wouldnt be overloaded to begin with.

The problem is that we are looking at rq->nr_running, which may include
RT tasks in addition to CFS tasks.  Since the presence of RT tasks
really has no bearing on the balance status of CFS tasks, this throws
the calculation off.

This patch changes the logic to only consider the number of CFS tasks
when making the decision to optimze the wake-idle.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
CC: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>