Re: [GIT PULL] sched/core for v2.6.32 [LWN.net]

From:		Mike Galbraith <efault-AT-gmx.de>
To:		Jesper Juhl <jj-AT-chaosbits.net>
Subject:		Re: [GIT PULL] sched/core for v2.6.32
Date:		Sun, 13 Sep 2009 08:41:54 +0200
Cc:		Ingo Molnar <mingo-AT-elte.hu>, Tony Luck <tony.luck-AT-intel.com>, Linus Torvalds <torvalds-AT-linux-foundation.org>, linux-kernel-AT-vger.kernel.org, Peter Zijlstra <a.p.zijlstra-AT-chello.nl>

On Sun, 2009-09-13 at 00:07 +0200, Jesper Juhl wrote:
> On Sat, 12 Sep 2009, Ingo Molnar wrote:
> 

> > It was a statistical property based on performance considerations - 
> > and now we flipped it around based on latency and for kbuild 
> > performance/throughput reasons: Serge Belyshev reported a 7% 
> > increase on a quad due to this change and i measured a 1.5% 
> > peak-kbuild performance increase.
> > 
> Impressive. I wouldn't have expected that much gain by running the parent 
> first. Actually I personally would have expected child-first to perform 
> better since (in my experience) it's usually the child that's just forked 
> that matters the most.

How can waiting for child1 to run a bit before forking off child2 _not_
hurt?  The parent is the worker bee creator, the queen bee if you will.
Seems to me that making the queen wait until one egg hatches and ages a
bit before laying another egg is a very bad plan if the goal is to have
a hive full of short lived worker bees.

	-Mike