[Xen-devel] Powertop shows xenconsoled the reason why CPU wakes up from C-sleep states

["Roger Cruz" <roger.cruz@xxxxxxxxxxxxxxxxxxx>]

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

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