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Date: Mon, 23 Apr 2007 11:25:02 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Nick Piggin <npiggin@suse.de>
Cc: linux-kernel@vger.kernel.org,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Con Kolivas <kernel@kolivas.org>, Mike Galbraith <efault@gmx.de>,
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       Peter Williams <pwil3058@bigpond.net.au>,
       Thomas Gleixner <tglx@linutronix.de>, caglar@pardus.org.tr,
       Willy Tarreau <w@1wt.eu>, Gene Heskett <gene.heskett@gmail.com>,
       Mark Lord <lkml@rtr.ca>, Ulrich Drepper <drepper@redhat.com>
Subject: Re: [patch] CFS scheduler, -v5
Message-ID: <20070423092502.GA7972@elte.hu>
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* Nick Piggin <npiggin@suse.de> wrote:

> > yeah - but they'll all be quad core, so the SMP timeslice 
> > multiplicator should do the trick. Most of the CFS testers use 
> > single-CPU systems.
> 
> But desktop users could have have quad thread and even 8 thread CPUs 
> soon, [...]

SMT is indeed an issue, so i think what should be used to scale 
timeslices isnt num_online_cpus(), but the sum of all CPU's ->cpu_power 
value (scaled down by SCHED_LOAD_SCALE). That way if the thread is not a 
'full CPU', then the scaling will be proportionally smaller. Can you see 
any hole in that?

	Ingo