xen discuss - Aug 2008 - xVM-enabled kernel disabling CPU power management ?

Hi,

I''ve started to play with CPU power management today, and that
didn''t work at first.

By default, my OpenSolaris host boots with a xVM enabled kernel. I reboot it
with a standard kernel to see, and then CPU power management works perfectly.

I searched a long time, but I didn''t find anywhere a word about CPU
power management disabled when using an xVM kernel.

Anybody has some information about that ? Is it definitely impossible to have
CPU power management when using xVM features ?
 
 
This message posted from opensolaris.org

On Sun, Aug 03, 2008 at 06:35:35AM -0700, Vincent Planchenault
wrote:
> I''ve started to play with CPU power management today, and that
didn''t work at first.
> 
> By default, my OpenSolaris host boots with a xVM enabled kernel. I
> reboot it with a standard kernel to see, and then CPU power
> management works perfectly.
> 
> I searched a long time, but I didn''t find anywhere a word about
CPU
> power management disabled when using an xVM kernel.
> 
> Anybody has some information about that ? Is it definitely
> impossible to have CPU power management when using xVM features ?
Currently it doesn''t work and is not supported. It''s on our
list of
things to fix, but it''s not particularly high up the list.

> On Sun, Aug 03, 2008 at 06:35:35AM -0700, Vincent
> Planchenault wrote:
> > Is it definitely impossible to have CPU power management when using
> > xVM features ?
> 
> Currently it doesn''t work and is not supported. It''s
> on our list of
> things to fix, but it''s not particularly high up the
> list.
Is there anything I can do to help in this specific area ?
 
 
This message posted from opensolaris.org

On Mon, Aug 04, 2008 at 02:06:34PM -0700, Vincent Planchenault
wrote:
> > On Sun, Aug 03, 2008 at 06:35:35AM -0700, Vincent
> > Planchenault wrote:
> > > Is it definitely impossible to have CPU power management when
using
> > > xVM features ?
> > 
> > Currently it doesn''t work and is not supported. It''s
on our list
> > of things to fix, but it''s not particularly high up the list.
> 
> Is there anything I can do to help in this specific area ?
I''m not sure what to suggest other than "yes, dive in and fix
it" :-)

At the moment there hasn''t been much investigation of what is
required. Perhaps someone else from the project can give you better
advice.

On Tue, Aug 05, 2008 at 07:32:54AM +0100, David Edmondson wrote:
> > > > Is it definitely impossible to have CPU power management
when using
> > > > xVM features ?
> > > 
> > > Currently it doesn''t work and is not supported.
It''s on our list
> > > of things to fix, but it''s not particularly high up the
list.
> > 
> > Is there anything I can do to help in this specific area ?
> 
> I''m not sure what to suggest other than "yes, dive in and fix
it" :-)
> 
> At the moment there hasn''t been much investigation of what is
> required. Perhaps someone else from the project can give you better
> advice.
The first step would probably be to look at what''s implemented in the
upcoming Xen 4.0 (which has power management support for CPUs) and see
how that would map to Solaris''s support.

regards
john