From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Dunlap Subject: Re: CAP and performance problem Date: Thu, 6 Jun 2013 11:44:01 +0100 Message-ID: <51B067F1.1010008@eu.citrix.com> References: <519B3832.30608@di.unipmn.it> <1370451024.18519.190.camel@Solace> <1370452319.18519.197.camel@Solace> <51AF6FBD.9090007@di.unipmn.it> <1370507870.18519.224.camel@Solace> <51B04F0E.5040506@di.unipmn.it> <51B066CC.4060900@ts.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51B066CC.4060900@ts.fujitsu.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Juergen Gross Cc: Dario Faggioli , Massimo Canonico , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 06/06/13 11:39, Juergen Gross wrote: > On 06.06.2013 10:57, Massimo Canonico wrote: >> >> On 06/06/2013 10:37 AM, Dario Faggioli wrote: >>> On mer, 2013-06-05 at 19:05 +0200, Massimo Canonico wrote: >>>> Hi Dario, >>>> and thanks for these test. >>>> >>>> I forgot to ask you which xen version has beed used for your >>>> experiments. >>>> >>> Yeah, me too! :-) >>> >>> I'm using xen-unstable, pulled yesterday (commit id >>> e430510e5cbbfcdc1077739292def633e70fedea), compiled and installed on a >>> Debian unstable system. Dom0 kernel is a bit old, as it's a 3.6. >>> >>> What about you? >> xen 4.2.2 >> kernel dom0: 3.8.11-200.fc18.x86_64 > > Just had an idea: is there any other load on the system during your > test (other > domains, dom0 load)? If not, it could be that the power management is > reducing > the cpu speed during idle (when the cap applies). This could lead to > reduced > performance overall. > > You can test this by setting the xen hypervisor boot option > > cpufreq=none > > and run your test again (with and without cap). Ah, genius Juergen! That would make total sense. -George