Re: [rfc][patch] improved interactive starvation patch against 2.6.16

From: Willy Tarreau
Date: Thu Mar 30 2006 - 06:08:15 EST


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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