From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juergen Gross Subject: Re: CAP and performance problem Date: Thu, 06 Jun 2013 15:02:59 +0200 Message-ID: <51B08883.50003@ts.fujitsu.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> <51B067F1.1010008@eu.citrix.com> <51B08606.9090105@di.unipmn.it> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51B08606.9090105@di.unipmn.it> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Massimo Canonico Cc: George Dunlap , Dario Faggioli , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 06.06.2013 14:52, Massimo Canonico wrote: > > On 06/06/2013 12:44 PM, George Dunlap wrote: >> 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 >> > Unfortunately, this did not change much. I set "cpufreq=none" in the boot line You added the boot parameter for the hypervisor, not dom0? And (please forgive my paranoia) you rebooted the complete system after that? > and restart my experiment. > With no cap I got 298.029 > with cap=50% I got 910.272 > (average values of 3 experiments for each cap setting) > > dom0 load during the experiment is less than 1% (that says xentop) What was the load reported by xentop for your domu? Could you try: xl vcpu-list; sleep 10; xl vcpu-list when the test is running and post the output? Juergen -- Juergen Gross Principal Developer Operating Systems PBG PDG ES&S SWE OS6 Telephone: +49 (0) 89 3222 2967 Fujitsu Technology Solutions e-mail: juergen.gross@ts.fujitsu.com Domagkstr. 28 Internet: ts.fujitsu.com D-80807 Muenchen Company details: ts.fujitsu.com/imprint.html