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] [PATCH] 1/2: cpufreq/PowerNow! in Xen: Time and platform

To: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, Rik van Riel <riel@xxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] 1/2: cpufreq/PowerNow! in Xen: Time and platform changes
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Fri, 31 Aug 2007 10:23:00 +0100
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Mark Langsdorf <mark.langsdorf@xxxxxxx>
Delivery-date: Fri, 31 Aug 2007 02:23:53 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <D470B4E54465E3469E2ABBC5AFAC390F013B21AE@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>
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: AcfrFw31vuvSGdZTRFKPYpfObYtJawAXY3uQAA76jnI=
Thread-topic: [Xen-devel] [PATCH] 1/2: cpufreq/PowerNow! in Xen: Time and platform changes
User-agent: Microsoft-Entourage/11.3.6.070618
On 31/8/07 03:42, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:

> d) I guess final power saving of cpufreq (either approach) is not obvious,
> since average CPU utilization should be higher than native which is the
> goal of virtualization. C-state may be more interesting.

Yes!

I would love to see some C-state support in Xen, both for normal idle-loop
execution and, as further work, deeper sleeps for hot-unplugged CPUs (which
can be under control of management/performance tools in dom0).

In the now prevalent multi-core environments, I'll be surprised if it's not
better to deep-sleep whole cores rather than run them all at continually
varying half speeds. And, simultaneously with making C-states a viable
power-saving model, I think multi-core makes it harder to decide what the
'right' per-cpu cpu frequency changes should be.

 -- Keir



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

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