Description of problem: Running 'virsh list' or 'xm list' consumes too much CPU time. When the number pf VMs is relatively high (10) and they are loaded with network activity the answer to the vmlist command may become very long (minutes) or may sometimes never complete. This problem existed to some extent in RHEL 5.1, but has gotten worse in RHEL 5.2. It appears xenstored is taking up most of the CPU time. Version-Release number of selected component (if applicable): xen-3.0.3-41.el5 How reproducible: Can be reproduced after a fashion by running 'xm list' or 'virsh list' in a while loop in a script: #!/bin/bash trap "exit;" INT while true; do xm list &> /dev/null; usleep 5000;done If you taskset the script to a single CPU, it will consume >75% of that CPU. Steps to Reproduce: 1. See above. Actual results: 'xm list'/xenstored takes up lots of CPU time and/or runs slowly when there are lots of VMs on the system. Expected results: 'xm list'/xenstored shouldn't consume as much CPU time. Additional info: http://lists.xensource.com/archives/html/xen-devel/2006-10/msg00487.html A workaround that we've come up with is to mount /var/lib/xenstored on tmpfs. This reduces the overall system load when 'xm list' is run.
This request was evaluated by Red Hat Product Management for inclusion in a Red Hat Enterprise Linux maintenance release. Product Management has requested further review of this request by Red Hat Engineering, for potential inclusion in a Red Hat Enterprise Linux Update release for currently deployed products. This request is not yet committed for inclusion in an Update release.
Created attachment 311576 [details] Allow putting xenstored on tmpfs NB, with this patch applied, the user still needs to opt-in by setting XENSTORED_TMPFS=yes in /etc/sysconfig/xend
*** Bug 434146 has been marked as a duplicate of this bug. ***
Built into xen-3.0.3-67.el5
The performance is increased by a huge factor. Tested with 10-15 virt machines and it did not consume more than 20% of processor with xm list running all the time.
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on therefore solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHBA-2009-0118.html