linux-kernel - Re: [PATCH] sched.c: Be a bit more conservative in SMP

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Date:	Tue, 19 Sep 2006 19:50:46 +0200
From:	"Antonio Vargas" <windenntw@...il.com>
To:	"Ludovic Drolez" <ldrolez@...box.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sched.c: Be a bit more conservative in SMP

On 9/19/06, Ludovic Drolez <ldrolez@...box.com> wrote:
> Vincent Pelletier <vincent.plr <at> wanadoo.fr> writes:
> > I'll do some tests soon to see which version gives better performance at a
> > higher level than just process migration cost - if different at all.
>
> I think that your patch should improve the performance because process
> migrations are expensive (cache miss) and should be avoided when not
> really necessary.
>
> Cheers,
>
>   Ludovic.
>

A variant on this theme would be (not tested or somewhat, just a
random idea for considering):

1. find if the process is a cpu-hog, if not then ignore

2. find somehow how much time has this process on it's current cpu

3. then, instead of always substracting 1 from th current load on the
current cpu, substract for example 1...0 when running from 0 to 60
seconds... this way cpu hogs would only rotate slowly?

in code:

number_to_sub_from_queue_load = (256 - min(256,
time_from_last_change_of_cpu)) >> 8;

somehow managing to get fixedpoint loadlevels on the runqueues would
make this work better....

-- 
Greetz, Antonio Vargas aka winden of network

http://network.amigascne.org/
windNOenSPAMntw@...il.com
thesameasabove@...gascne.org

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