linux-kernel - Re: [patch] restore sched_exec load balance heuristics

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Date:	Thu, 6 Nov 2008 12:32:55 -0800
From:	Ken Chen <kenchen@...gle.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Mike Galbraith <efault@....de>
Subject: Re: [patch] restore sched_exec load balance heuristics

On Thu, Nov 6, 2008 at 12:07 PM, Ingo Molnar <mingo@...e.hu> wrote:
> ok, this should be solved - but rather at the level of
> sched_balance_self(): it should never migrate this task over to
> another cpu, it should take away this task's load from the current
> CPU's load when considering migration.

There are two callers to sched_balance_self().  In the sched_fork
path, sched_balance_self will balance the newly forked task.  I think
it is OK to bounce a newly forked task to another CPU since current
CPU will be busy when fork returns in the parent process.

And if sched_balance_self() needs to different between fork / exec
load balance, it has to check a flag from function argument, which I
think it is better to just short circuit in sched_exec() directly.

- Ken
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