From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dario Faggioli <dario.faggioli@citrix.com>
Subject: Re: [PATCH] credit: Change default timeslice to 5ms
Date: Wed, 5 Mar 2014 17:33:40 +0100
Message-ID: <1394037220.16409.30.camel@Solace>
References: <1394036976-484-1-git-send-email-george.dunlap@eu.citrix.com>
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To: George Dunlap <george.dunlap@eu.citrix.com>
Cc: Marcus Granado <Marcus.Granado@eu.citrix.com>, Keir Fraser <keir@xen.org>, Tim Deegan <tim@xen.org>, Jan Beulich <jbeulich@suse.com>, xen-devel@lists.xen.org
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On mer, 2014-03-05 at 16:29 +0000, George Dunlap wrote:
> The 30ms timeslice was chosen nearly a decade ago now, with cpu
> "burning" workloads in mind.  In the mean time, processors have gotten
> faster and VMEXITs have gotten faster.  A timeslice of 30ms has a
> major cost when running latency-sensitive workloads like network or
> audio streaming: getting caught behind just one or two other VMs can
> introduce a processing delay of up to 60ms, and the "round-robin"
> nature of the credit scheduler means this delay may be introduced
> every time the VM yields for periods of time.
>=20
> The XenServer performance team at Citrix have done extensive testing
> with various timeslices, including 30ms, 10ms, 5ms, and 2ms.  None of
> the workloads exhibited any performance degradation with a 5ms
> timeslice.
>=20
> Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com>
> ---
> CC: Jan Beulich <jbeulich@suse.com>
> CC: Tim Deegan <tim@xen.org>
> CC: Keir Fraser <keir@xen.org>
> CC: Dario Faggioli <dario.faggioli@citrix.com>
> CC: Marcus Granado <Marcus.Granado@eu.citrix.com>
> ---
>
Reviewed-by: Dario Faggioli <dario.faggioli@citrix.com>

Regards,
Dario

--=20
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)


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