Roger Cruz
2011-Mar-02 18:08 UTC
[Xen-devel] Powertop shows xenconsoled the reason why CPU wakes up from C-sleep states
I''ve been examining battery drain issues and when we run a PV linux kernel guest on Xen 3.4 with a dom0 2.6.32 kernel, I can see that xenconsoled is the one marked as responsible for a big percentage of the wake ups (using Powertop). Using strace, I can see that xenconsoled is pending in select without a timeout. that is, the application never really runs when the cpu wakes up. Using Xentrace, I can see that VCPUs are awaked, a few hypercalls from the kernel take place and then it puts itself to sleep. Then in about 30 pm ticks, the other CPU wakes up to run vcpu #2, which executes pretty much the same hypercalls and puts itself to sleep. This goes back and forth causing each CPU to wake up momentarily and go to sleep again. I did some research on the web and this thread appears to be relevant. Even though I don''t see events/0, I see xenconsoled which was mentioned this thread. http://www.gossamer-threads.com/lists/linux/kernel/1281515 Has anyone else seen this type of ping-pong behavior? Any idea how to fix this? thanks Roger _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel