WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

Re: [Xen-devel] RFC: cpu frequency scaling

To: "Petersson, Mats" <Mats.Petersson@xxxxxxx>, Rik van Riel <riel@xxxxxxxxxx>
Subject: Re: [Xen-devel] RFC: cpu frequency scaling
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Thu, 26 Oct 2006 15:09:05 +0100
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Delivery-date: Thu, 26 Oct 2006 07:21:17 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <907625E08839C4409CE5768403633E0B018E167E@xxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: Acb4ergNrMs0UK6BS3msZ8JVGx7G3AAf4+VQAAOA/YU=
Thread-topic: [Xen-devel] RFC: cpu frequency scaling
User-agent: Microsoft-Entourage/11.2.5.060620


On 26/10/06 1:35 pm, "Petersson, Mats" <Mats.Petersson@xxxxxxx> wrote:

> So you need to get the actual load of each physical CPU, then sort them
> "per socket" and do any changes based on the highest (or lowest) load of
> the actual socket. I'm not sure if all the necessary information is
> available in Dom0 unless it's also running on all available cores -
> however, neither am I sure if there's much point in pursuing the case
> where all CPU's are NOT in Dom0... Allowing those cores that are not
> Dom0-cores to have a driver-domain to control the speed would be
> sensible solution - interesting things happen, however, if someone puts
> core0 of a socket to Dom0, and Core1 of the same socket as DomU - you
> can't really control that one even with a driver domain...

We should state that as an assumption of the cpufreq domain (that it has a
one-to-one correspondence between VCPUs and PCPUs). We liekly also need an
interface to allow a domain to find out the 'topology' of its VCPUs, so that
the cpufreq drivers know which VCPUs share a socket, etc. They could also
work this out from cpuid in most cases I expect, but it's probably a better
fit with the Linux code to provide a generic 'topology info' interface and
people experimenting with NUMA will appreciate it too.

 -- Keir



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel

<Prev in Thread] Current Thread [Next in Thread>