From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ya-Yunn Su Subject: xenoprof passive mode overhead Date: Thu, 25 Mar 2010 14:06:26 -0400 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Hi all, I'd like to use xenoprof passive mode on domain-0 to calculate L2 cache missed for each guest domain. I setup oprofile daemon as followed opcontrol --start-daemon --event=LLC_MISSES:4000 --xen=/boot/xen-3.4.2.gz --vmlinux=/scratch/xen-3.4.2/build-linux-2.6.18-lttng-xen0_x86_32/vmlinux --passive-domains=1,2 --passive-images=/scratch/xen-3.4.0/build-linux-2.6.18-xenU_x86_32/vmlinux,/scratch/xen-3.4.0/build-linux-2.6.18-xenU_x86_32/vmlinux My machine has two cores and I pinned domain-0 to one core and guest domains to the other. When I ran oprofile to calculate cache misses/sec every 5 seconds on domain 0, I noticed that the transient CPU utilization can be as high as 30%. This affects the performance of whatever benchmark I'm running in the guest domain. Is this 30% overhead for domain-0 common or am I doing something obviously wrong? Any suggestion is appreciated. Thank you, Ya-Yunn