Stephen Neoh
2007-Nov-28 09:46 UTC
[Xen-users] Disable SMP and assign each OS to direct access CPU
I''m quite new to XEN here. I got a question to ask about the XEN configuration. Is it possible to disable the SMP function on the dom0 and assign each single domU to have direct access on the multicore processor like Intel Quadcore? _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Sadique Puthen
2007-Nov-28 10:03 UTC
Re: [Xen-users] Disable SMP and assign each OS to direct access CPU
Stephen Neoh wrote:> I''m quite new to XEN here. I got a question to ask about the XEN > configuration. Is it possible to disable the SMP function on the dom0 > and assign each single domU to have direct access on the multicore > processor like Intel Quadcore?Yes, Edit /etc/xend/xend-config.sxp and use (dom0-cpus x) to assign a single cpu to dom0. For domus, define vcpus = x and cpus = x in guest configuration file to assign a single core or cpu to a guest. See /etc/xen/xmexample1 for more details. --Sadique> ------------------------------------------------------------------------ > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Sadique Puthen
2007-Nov-28 10:38 UTC
Re: [Xen-users] Disable SMP and assign each OS to direct access CPU
Please reply to the list, not directly to me. There should be a lot of people in the list who can answer these questions better than me. IMHO, If the OS/hypervisor can detect the cpu cores, you should definitely be able to assign. Stephen Neoh wrote:> In that case, as i know, each physical core has it''s own id. Can i > assign a specific core id to a domU/domO? > > On Nov 28, 2007 6:03 PM, Sadique Puthen < sputhenp@redhat.com > <mailto:sputhenp@redhat.com>> wrote: > > Stephen Neoh wrote: > > I''m quite new to XEN here. I got a question to ask about the XEN > > configuration. Is it possible to disable the SMP function on the > dom0 > > and assign each single domU to have direct access on the multicore > > processor like Intel Quadcore? > > Yes, Edit /etc/xend/xend-config.sxp and use (dom0-cpus x) to assign a > single cpu to dom0. > > For domus, define vcpus = x and cpus = x in guest configuration > file to > assign a single core or cpu to a guest. See /etc/xen/xmexample1 > for more > details. > > --Sadique > > > ------------------------------------------------------------------------ > > > > _______________________________________________ > > Xen-users mailing list > > Xen-users@lists.xensource.com <mailto:Xen-users@lists.xensource.com> > > http://lists.xensource.com/xen-users > <http://lists.xensource.com/xen-users> > >-- Red Hat Software Services (India) Pvt. Ltd. 6th Floor, East Wing Marisoft-III, Marigold Premises Kalyani Nagar, Pune, Maharashtra India, Pin-411014 Mobile +919890354236 Tel: +91 20 40057363 If you want things you''ve never had, you have to do things you''ve never done. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Mark Williamson
2007-Dec-02 04:15 UTC
Re: [Xen-users] Disable SMP and assign each OS to direct access CPU
> IMHO, If the OS/hypervisor can detect the cpu cores, you should > definitely be able to assign. > > Stephen Neoh wrote: > > In that case, as i know, each physical core has it''s own id. Can i > > assign a specific core id to a domU/domO?Actually you can assign individual logical processors (i.e. hyperthreads, if you have them) to domains. By assigning all the logical processors on a core, you can assign a core to the domain; by assigning all the logical processors in a package you can assign all the cores in that package, and so on. Of course, the domain isn''t actually getting direct access to the processors - it still gets scheduled by Xen. But if you arrange in the domain config files (and in xend-config.sxp for dom0) that each is assigned to run only on one specific logical CPU then it''s basically equivalent to a domain running on each logical CPU all the time - because Xen won''t have anything else to schedule! It can be a performance win to assign a dedicated hyperthread (or potentially a core, but this would depend on your workload) to dom0. I''ve had the impression that dom0 doesn''t really need to be SMP anyhow to ensure decent performance to the domUs. Assigning at least a hyperthread to dom0 can improve IO performance, although if you assign a core to dom0 obviously other domains can''t use it for processing anymore. For other domains, you may still find it''s more flexible to let Xen schedule them across the available processors. You can still cap the amount of CPU a domain uses. But yes, you can pin domains to CPUs to get the effect of each core running a different domain. Hope this helps, Cheers, Mark> > On Nov 28, 2007 6:03 PM, Sadique Puthen < sputhenp@redhat.com > > <mailto:sputhenp@redhat.com>> wrote: > > > > Stephen Neoh wrote: > > > I''m quite new to XEN here. I got a question to ask about the XEN > > > configuration. Is it possible to disable the SMP function on the > > > > dom0 > > > > > and assign each single domU to have direct access on the multicore > > > processor like Intel Quadcore? > > > > Yes, Edit /etc/xend/xend-config.sxp and use (dom0-cpus x) to assign a > > single cpu to dom0. > > > > For domus, define vcpus = x and cpus = x in guest configuration > > file to > > assign a single core or cpu to a guest. See /etc/xen/xmexample1 > > for more > > details. > > > > --Sadique > > > > > > ------------------------------------------------------------------------ > > > > > _______________________________________________ > > > Xen-users mailing list > > > Xen-users@lists.xensource.com > > > <mailto:Xen-users@lists.xensource.com> > > > http://lists.xensource.com/xen-users > > > > <http://lists.xensource.com/xen-users>-- Dave: Just a question. What use is a unicyle with no seat? And no pedals! Mark: To answer a question with a question: What use is a skateboard? Dave: Skateboards have wheels. Mark: My wheel has a wheel! _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users