After upgrading to the most recent VirtIO drivers (from Fedora, version 0.1-65), I am noticing very weird CPU activity on my W2K8 R2 guests, that are running 2+ cores. Maybe someone can enlighten me ... Please see attached screenshots for the details.
The host is Ubuntu 13.04, running kernel 3.8.0. System is built on two 6-core Intel E5-2630L processors, with 64MB of RAM (32MB for each). I upgraded the VirtIO storage, VirtIO NIC, and VirtIO Balloon drivers last Friday from, I believe, version 0.1-30 (July 2012). Another bit of info that might be of value -- I also installed the "pm-utils" package for Ubuntu at the same time as upgrading the drivers, which was not installed previously.
In Windows, running the Performance Monitor, I notice that the processor counter "% C1 Time" is directly proportional to this weird activity. When the processor time shows ~20%+ and the total user/privileged CPU time is less than 1-2%, the % C1 Time is ~80% ... And when the processor time is where I expect it should be (a total of the user+privileged time), the % C1 Time is at about 100%.
This particular screenshot shows the C1 time averaging about 90%, with the processor time averaging about 10%. Total CPU usage is around 1-2%, and idle CPU is 98-99%.
I don't know whether or not the weird activity has something to do with pm-utils or the VirtIO drivers, nor do I know whether or not this is something I should be concerned about. Any thoughts, suggestions, or answers would be very much appreciated. Thank you so much.