Date: Thu, 30 Mar 2006 13:07:21 +0200
From: Willy Tarreau <willy@w.ods.org>
To: Mike Galbraith <efault@gmx.de>
Cc: lkml <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
       Andrew Morton <akpm@osdl.org>, Peter Williams <pwil3058@bigpond.net.au>,
       Nick Piggin <nickpiggin@yahoo.com.au>, Con Kolivas <kernel@kolivas.org>
Subject: Re: [rfc][patch] improved interactive starvation patch against 2.6.16
Message-ID: <20060330110721.GA4851@w.ods.org>
References: <1143713997.9381.28.camel@homer>
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Hi Mike,

On Thu, Mar 30, 2006 at 12:19:57PM +0200, Mike Galbraith wrote:
> Greetings,
> 
> The patch below alone makes virgin 2.6.16 usable in the busy apache
> server scenario, and should help quite a bit with other situations as
> well.
> 
> The original version helps a lot, but not enough, and the latency of
> being awakened in the expired array can be needlessly painful.  Ergo,
> speed up the array switch, and instead of unconditionally plunking all
> awakening tasks (including rt tasks, oops) into the expired array, check
> to see if the task has run since the last array switch first.  This
> leaves a theoretical hole for a stream of one-time waking tasks to
> starve the expired array indefinitely, but it deals with the real
> problem pretty nicely I think. 

Interesting.

> For the one or two folks on the planet testing my anti-starvation
> patches, I've attached an incremental to my 2.6.16 test release.

Thanks, I'll test this ASAP, though I'm clearly busy right now.

Cheers,
Willy

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