On Fri, Dec 05, 2008 at 04:42:57PM +0000, George Dunlap wrote: > IIRC, only w2k3sp2+, vista, and w2k8 have lazy TPR. Not positive > about w2k3sp1, but I think it doesn't. WinXP does not have lazy TPR > in any service pack, AFAIK. > > What service pack of w2k3 did you do those tests with? > I'm not sure, because the ISO was provided by a colleague. I think it's the original release of w2k3, with no service packs. However, what I was mostly curious about was why specifying apic when the guest was created made so much different to performance. Gary > Hopefully, sometime in the next few weeks, I'll be able to release my > 'xenalyze' tool, which will help a lot with analyzing what's really > going on with these kinds of workloads. > > -George > > On Fri, Dec 5, 2008 at 2:45 PM, Keir Fraser <keir.fraser@xxxxxxxxxxxxx> wrote: > > On 05/12/2008 14:03, "Gary Pennington" <Gary.Pennington@xxxxxxx> wrote: > > > >> My next question is: What is really happening when APIC is specified for > >> a windows guest and why does performance vary so much according to whether > >> it's specified or not? > > > > Older Windows kernels update the APIC TPR a lot, and unless you have a very > > modern Intel processor every one of those TPR updates causes a vmexit. > > > > Modern Windows (including possibly latest w2k3 service pack, but I'm not > > totally certain) includes lazy TPR, which gets rid of the vast majority of > > TPR updates, and hence will go much faster. > > > > -- Keir > > > > > > > > _______________________________________________ > > Xen-devel mailing list > > Xen-devel@xxxxxxxxxxxxxxxxxxx > > http://lists.xensource.com/xen-devel > > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@xxxxxxxxxxxxxxxxxxx > http://lists.xensource.com/xen-devel -- Gary Pennington Solaris Core OS Sun Microsystems Gary.Pennington@xxxxxxx _______________________________________________ et-mgmt-tools mailing list et-mgmt-tools@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/et-mgmt-tools
