linux-kernel - Re: [ck] Re: [ANNOUNCE] Staircase Deadline cpu scheduler version 0.45

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Date:	Mon, 23 Apr 2007 00:35:53 +1000
From:	Con Kolivas <kernel@...ivas.org>
To:	Willy Tarreau <w@....eu>
Cc:	ck@....kolivas.org, Michael Gerdau <mgd@...hnosis.de>,
	Nick Piggin <npiggin@...e.de>,
	Gene Heskett <gene.heskett@...il.com>,
	Al Boldi <a1426z@...ab.com>,
	Bill Huey <billh@...ppy.monkey.org>,
	Mike Galbraith <efault@....de>,
	linux kernel mailing list <linux-kernel@...r.kernel.org>,
	William Lee Irwin III <wli@...omorphy.com>,
	Peter Williams <pwil3058@...pond.net.au>,
	Matt Mackall <mpm@...enic.com>
Subject: Re: [ck] Re: [ANNOUNCE] Staircase Deadline cpu scheduler version 0.45

On Monday 23 April 2007 00:22, Willy Tarreau wrote:
> On Sun, Apr 22, 2007 at 10:18:32PM +1000, Con Kolivas wrote:
> > On Sunday 22 April 2007 21:42, Con Kolivas wrote:
> >
> > Willy I'm still investigating the idle time and fluctuating load as a
> > separate issue. Is it possible the multiple ocbench processes are
> > naturally synchronising and desynchronising and choosing to sleep and/or
> > run at the same time? I can remove the idle time entirely by running
> > ocbench at nice 19 which means they are all forced to run at basically
> > the same time by the scheduler.
> >
> > Anyway the more important part is... Can you test this patch please? Dump
> > all the other patches I sent you post 045. Michael, if you could test too
> > please?
>
> OK, it's better now. All tasks equally run.

Excellent thank you very much (again!)

> X is still somewhat jerky, even 
> at nice -19. I'm sure it happens when it's waiting in the other array. We
> should definitely manage to get rid of this if we want to ensure low
> latency.

Yeah that would be correct. It's clearly possible to keep the whole design 
philosophy and priority system intact with SD and do away with the arrays if 
it becomes a continuous stream instead of two arrays but that requires some 
architectural changes. I've been concentrating on nailing all the remaining 
issues (and they kept cropping up as you've seen *blush*). However... I 
haven't quite figured out how to do that architectural change just yet either 
so let's just iron out all the bugs out of this now.

> Just FYI, the idle is often close to zero and the load is often close to
> 30, even if still fluctuating :

> Hoping this helps !

I can say without a shadow of a doubt it has helped :) I'll respin the patch 
slightly differently and post it and release as v0.46.

> Willy

-- 
-ck
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