From mboxrd@z Thu Jan 1 00:00:00 1970 From: Massimo Canonico Subject: Re: CAP and performance problem Date: Wed, 22 May 2013 16:42:17 +0200 Message-ID: <519CD949.5040906@di.unipmn.it> References: <519B3832.30608@di.unipmn.it> <519B6089.9050909@di.unipmn.it> <1369141576.12423.73.camel@Solace> <519B8474.40501@di.unipmn.it> <1369147649.12423.98.camel@Solace> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1369147649.12423.98.camel@Solace> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Dario Faggioli Cc: George Dunlap , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org I have run other tests, changing the run duration but it seems that CAP mechanism has some problem. I always get response time too much longer (3 times instead of 2). Any idea about how to fix the problem? Did someone try to make a similar experiment? Thanks, M On 05/21/2013 04:47 PM, Dario Faggioli wrote: > On mar, 2013-05-21 at 15:28 +0100, Massimo Canonico wrote: >> On 05/21/2013 03:06 PM, Dario Faggioli wrote: >>> Also, when inspecting the vCPU utilization, do you see the VM vCPU busy >>> up to 100% without cap (or with cap set to 100) and, OTOH, up to 50% >>> with cap set to 50? >> I have monitored the CPU usage with xentop during the experiment and >> I got what you said: my application always use the total amonut of CPU >> available. >> > Ok. > >>> Well, looks like a scheduling issue, or, in any case, one where >>> something is interacting with the scheduling. Can you perhaps boot Dom0 >>> so that it uses only 2 or 3 cores (or arrange for that later, e.g., with >>> cpupools) and pin the vCPU of the VM on the 4th one? >> In my experiments, I pin the vCPU of the VM on one core and other cores >> are pinned to Dom0. >> [root@csitest ~]# xl vcpu-list >> Name ID VCPU CPU State Time(s) CPU >> Affinity >> Domain-0 0 0 0 --- 383.3 0 >> Domain-0 0 1 0 -b- 358.1 0 >> Domain-0 0 2 0 -b- 224.3 0 >> Domain-0 0 3 0 r-- 256.8 0 >> rubis-web 1 0 2 -b- 9250.9 2 >> >> (rubis-web is, of course, the VM where my application run) >> >> Is this configuration what you meant? >> > Sort of. However, since (you said) you have 4 cores, what I was thinking > was more a situation where you have the 4 Dom0 vCPUs pinned to cores > 0-2, and the VM vCPU pinned to core 3. > > You should be able to achieve that by doing right this: > > # xl vcpu-pin 0 all 0-2 > # xl vcpu-pin rubis-web all 3 > > Does it make sense? Oh, and also, you have 4 _actual_cores_, right? Or > is there any hyperthreading involved? > > Dario >