From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juergen Gross Subject: Re: Poor HVM performance with 8 vcpus Date: Wed, 14 Oct 2009 11:11:42 +0200 Message-ID: <4AD595CE.8090402@ts.fujitsu.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: Gianluca Guida , "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org Keir Fraser wrote: > On 14/10/2009 09:16, "Juergen Gross" 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@ts.fujitsu.com Otto-Hahn-Ring 6 Internet: ts.fujitsu.com D-81739 Muenchen Company details: ts.fujitsu.com/imprint.html