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/
Home Products Support Community News


RE: [Xen-devel] [PATCH][Retry 1] 4/4: cpufreq/PowerNow! in Xen: PowerNow

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: RE: [Xen-devel] [PATCH][Retry 1] 4/4: cpufreq/PowerNow! in Xen: PowerNow! changes
From: "Langsdorf, Mark" <mark.langsdorf@xxxxxxx>
Date: Fri, 31 Aug 2007 11:56:15 -0500
Delivery-date: Fri, 31 Aug 2007 09:57:17 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <C2FDF44E.15192%Keir.Fraser@xxxxxxxxxxxx>
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>
References: <200708301201.32030.mark.langsdorf@xxxxxxx> <C2FDF44E.15192%Keir.Fraser@xxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: Acfr5NmmGClNJFfYEdySawAX8io7RQACpUAw
Thread-topic: [Xen-devel] [PATCH][Retry 1] 4/4: cpufreq/PowerNow! in Xen: PowerNow! changes
> On 30/8/07 18:01, "Mark Langsdorf" <mark.langsdorf@xxxxxxx> wrote:
> > Patch 4 covers the changes necessary to the PowerNow! driver
> > to make it correctly associate shared cores under Xen.
> Should we have a copy of that file in powernow-k8-xen.c? Can 
> the patched file work correctly in a native Linux build?

The patch is the same patch I submitted upstream for the native
2.6.23 Linux kernel.  

In native mode, the kernel creates a cpumask for each cpu that
lists its sibling cores.  Unfortunately, Xen doesn't do that.
The patch instead reads and parses the _PSD ACPI structure,
which indicates which cores share pstates with other cores.  
(Frankly, _PSD is the right way to do it, but the other way
was easier until Linux got ACPI support for _PSD).  If Xen
were using the same kernel version as Linux, the patch wouldn't
be necessary.

-Mark Langsdorf
Operating System Research Center

Xen-devel mailing list