Date: Mon, 21 Sep 2009 13:20:59 +0200
From: Arjan van de Ven <arjan@infradead.org>
To: Johannes Buchner <buchner.johannes@gmx.at>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Influence of optimization level, preemption and scheduler on
 boot time
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References: <20090921232553.c97560c7.buchner.johannes@gmx.at>
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On Mon, 21 Sep 2009 23:25:53 +1200
Johannes Buchner <buchner.johannes@gmx.at> wrote:

> Hi all.
> 
> I measured the kernel (and system) boot times while varying the
> parameters:
>  - Optimization level: -Os, -O2 and also -O3
>  - Preemptive model
>  - Scheduler: CFQ, Anticipatory, Deadline, Noop
> 
> My conclusion was that the optimization level and the preemptive model
> had no significant influence on speed. CFQ let my system boot several
> seconds faster than the other schedulers.
> 
> Graphs can be found at:
> http://johannes.jakeapp.com/blog/?p=913
> 
> This conclusion may not be true for all situations, but I found it
> interesting that the optimization level is so irrelevant.
> 

it's interesting to see that the IO scheduler mattered.. 
I would think that (s)readahead makes the IO scheduler irrelevant for
boot time...

--
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
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