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In-Reply-To: <87hbvdiogq.fsf@depni.sinp.msu.ru>
References: <20090906205952.GA6516@elte.hu> <87hbvdiogq.fsf@depni.sinp.msu.ru>
Date: Tue, 8 Sep 2009 10:47:25 -0700
Message-ID: <4807377b0909081047kfad088j694bd2b806075c5f@mail.gmail.com>
Subject: Re: Epic regression in throughput since v2.6.23
From: Jesse Brandeburg <jesse.brandeburg@gmail.com>
To: Serge Belyshev <belyshev@depni.sinp.msu.ru>
Cc: Ingo Molnar <mingo@elte.hu>, Con Kolivas <kernel@kolivas.org>,
       linux-kernel@vger.kernel.org, Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Mike Galbraith <efault@gmx.de>
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On Tue, Sep 8, 2009 at 5:57 AM, Serge
Belyshev<belyshev@depni.sinp.msu.ru> wrote:
>
> Hi. I've done measurments of time taken by make -j4 kernel build
> on a quadcore box.  Results are interesting: mainline kernel
> has regressed since v2.6.23 release by more than 10%.

Is this related to why I now have to double the amount of threads X I
pass to make -jX, in order to use all my idle time for a kernel
compile?  I had noticed (without measuring exactly) that it seems with
each kernel released in this series mentioned, I had to increase my
number of worker threads, my common working model now is (cpus * 2) in
order to get zero idle time.

Sorry I haven't tested BFS yet, but am interested to see if it helps
interactivity when playing flash videos on my dual core laptop.