All of lore.kernel.org
 help / color / mirror / Atom feed
* RE: Setting dom0-cpus to 0 doesn't use all cpus asdocumented
@ 2006-05-09 15:05 Ian Pratt
  2006-05-09 15:44 ` Ryan Harper
  0 siblings, 1 reply; 6+ messages in thread
From: Ian Pratt @ 2006-05-09 15:05 UTC (permalink / raw)
  To: Carb, Brian A, Xen-devel
  Cc: Subrahmanian, Raj, Krysan, Susan, Puthiyaparambil, Aravindh,
	Vessey, Bruce A

> The comments for dom0-cpus in the xend-config.sxp file 
> indicate that setting this value to 0 in an SMP system will 
> cause dom0 to use all the available CPUs. However, it appears 
> as if setting this value to 0 does not change the number of 
> CPUs at all.
> 
> I'm running SLES10 Beta 11 and xen-unstable changeset 9960 on 
> a Unisys ES7000 with 32 CPUs and 32GB memory. In 
> xend-config.sxp, dom0-cpus is set to 0. When xen dom0 boots, 
> it is using all 32 procs (as reported by 'grep processor 
> /proc/cpuinfo | wc -l').
> 
> If I edit the xend-config.sxp file, change the value of 
> dom0-cpus to 1, and restart xend, dom0 correctly uses 1 CPUs. 
> If I then change dom0-cpus to 0 and restart xend, dom0 still 
> uses 1 cpu. The only way to have dom0 use 32 cpus again is to 
> either set the value of dom0-cpus to 32, or reboot xen.
> 
> Has anyone else seen this behavior?

You can just use the normal xm commands to vary the number of CPUs.
Restarting xend is a rather brutal way of trying to achieve the same
thing...

Ian

^ permalink raw reply	[flat|nested] 6+ messages in thread
* RE: Setting dom0-cpus to 0 doesn't use all cpus asdocumented
@ 2006-05-09 15:52 Ian Pratt
  2006-05-09 16:01 ` Jan Beulich
  0 siblings, 1 reply; 6+ messages in thread
From: Ian Pratt @ 2006-05-09 15:52 UTC (permalink / raw)
  To: Ryan Harper
  Cc: Xen-devel, Krysan, Susan, Puthiyaparambil, Aravindh,
	Subrahmanian, Raj, Vessey, Bruce A, Carb, Brian A

 
> > You can just use the normal xm commands to vary the number of CPUs.
> > Restarting xend is a rather brutal way of trying to achieve 
> the same 
> > thing...
> 
> Is it worth keeping dom0-cpus then?

Yes, it sets it when xend starts.

Ian

^ permalink raw reply	[flat|nested] 6+ messages in thread
* RE: Setting dom0-cpus to 0 doesn't use all cpus asdocumented
@ 2006-05-09 15:57 Carb, Brian A
  2006-05-09 16:04 ` Ryan Harper
  0 siblings, 1 reply; 6+ messages in thread
From: Carb, Brian A @ 2006-05-09 15:57 UTC (permalink / raw)
  To: Ryan Harper, Ian Pratt
  Cc: Puthiyaparambil, Aravindh, Xen-devel, Krysan, Susan,
	Subrahmanian, Raj, Vessey, Bruce A

We discovered this when running the xm-test suite. One of the tests
(01_enforce_dom0_cpus) changes the number of cpus by editing the
xend-config.sxp file and restarting xend. Should this test be updated to
use the method Ian suggested, to vary the number of cpus, rather than
restarting xend?

brian carb (610-648-2437 or N2 385-2437)
unisys cmp technology lab
malvern, pa
brian.carb@unisys.com

THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY
MATERIAL and is thus for use only by the intended recipient. If you
received this in error, please contact the sender and delete the e-mail
and its attachments from all computers. 

-----Original Message-----
From: Ryan Harper [mailto:ryanh@us.ibm.com] 
Sent: Tuesday, May 09, 2006 11:45 AM
To: Ian Pratt
Cc: Carb, Brian A; Xen-devel@lists.xensource.com; Subrahmanian, Raj;
Krysan, Susan; Puthiyaparambil, Aravindh; Vessey, Bruce A
Subject: Re: [Xen-devel] Setting dom0-cpus to 0 doesn't use all cpus
asdocumented

* Ian Pratt <m+Ian.Pratt@cl.cam.ac.uk> [2006-05-09 10:07]:
> > The comments for dom0-cpus in the xend-config.sxp file indicate that

> > setting this value to 0 in an SMP system will cause dom0 to use all 
> > the available CPUs. However, it appears as if setting this value to 
> > 0 does not change the number of CPUs at all.
> > 
> > I'm running SLES10 Beta 11 and xen-unstable changeset 9960 on a 
> > Unisys ES7000 with 32 CPUs and 32GB memory. In xend-config.sxp, 
> > dom0-cpus is set to 0. When xen dom0 boots, it is using all 32 procs

> > (as reported by 'grep processor /proc/cpuinfo | wc -l').
> > 
> > If I edit the xend-config.sxp file, change the value of dom0-cpus to

> > 1, and restart xend, dom0 correctly uses 1 CPUs.
> > If I then change dom0-cpus to 0 and restart xend, dom0 still uses 1 
> > cpu. The only way to have dom0 use 32 cpus again is to either set 
> > the value of dom0-cpus to 32, or reboot xen.
> > 
> > Has anyone else seen this behavior?
> 
> You can just use the normal xm commands to vary the number of CPUs.
> Restarting xend is a rather brutal way of trying to achieve the same 
> thing...

Is it worth keeping dom0-cpus then?


--
Ryan Harper
Software Engineer; Linux Technology Center IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253
ryanh@us.ibm.com

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2006-05-09 16:04 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2006-05-09 15:05 Setting dom0-cpus to 0 doesn't use all cpus asdocumented Ian Pratt
2006-05-09 15:44 ` Ryan Harper
  -- strict thread matches above, loose matches on Subject: below --
2006-05-09 15:52 Ian Pratt
2006-05-09 16:01 ` Jan Beulich
2006-05-09 15:57 Carb, Brian A
2006-05-09 16:04 ` Ryan Harper

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.