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Re: [Xen-devel] Poor HVM performance with 8 vcpus

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>

From: Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>

Date: Wed, 14 Oct 2009 11:11:42 +0200

Cc: Gianluca Guida <Gianluca.Guida@xxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>

Delivery-date: Wed, 14 Oct 2009 02:12:11 -0700

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Keir Fraser wrote: > On 14/10/2009 09:16, "Juergen Gross" <juergen.gross@xxxxxxxxxxxxxx> wrote: > >> as the performance of BS2000 seems to be hit by OOS optimization, I'm >> thinking of making a patch to disable this feature by a domain parameter. >> >> Is there a way to do this without having to change all places where the >> #if statements are placed? >> I think there should be some central routines where adding an "if" could >> be enough (setting oos_active to 0 seems not to be enough, I fear). >> >> Do you have any hint? > > How about disabling it for domains with more than four VCPUs? Have you > measured performance with OOS for 1-4 VCPU guests? This is perhaps not > something that needs to be baked into guest configs. The same benchmark with 4 vcpus showed an improvement of about 6 % with OOS disabled. A 1 vcpu BS2000 showed no change in performance. And as Tim writes: there are systems with more than 4 vcpus which are still faster with OOS optimization active. Juergen -- Juergen Gross Principal Developer Operating Systems TSP ES&S SWE OS6 Telephone: +49 (0) 89 636 47950 Fujitsu Technolgy Solutions e-mail: juergen.gross@xxxxxxxxxxxxxx Otto-Hahn-Ring 6 Internet: ts.fujitsu.com D-81739 Muenchen Company details: ts.fujitsu.com/imprint.html _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel

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