On 12/06/2009 01:28 PM, Gareth Bult wrote:
Hi, Specific example of SMP slowdowns; Two hosts (A), (B) running Ubuntu 9.10. One guest on (B) running Ubuntu 9.10 on two cores. VPN connection (OpenVPN) between host (A) and Guest. Copy file over VPN from host (A) to Guest over VPN. Copy seems slow. Guest CPU usage is around 25% using "top" inside guest. Host A usage is minimal (5-10%). Host B CPU usage is around 160%. I'm expecting Host (B) usage to be ~ 30% ish - this is a huge discrepancy. I'm also noticing during lots of disk/network IO (virtio driver) whereas client / VM load averages tend to be up around the 1.0 mark, looking at the host the load average is showing 10+. (not a specific problem, but curious and concerning) In real terms, if I do a raw copy (not via the VPN, so it's all IO and no CPU) the copy (scp) runs through at around 40Mb/sec. Via the VPN, I'm getting ~ 6Mb/sec. If I reduce the VM to 1 core, I get 12Mb/sec .. so doubling the cores on the VM halves the speed!
Is the time reported on the host user time or system time? Please post a kvm_stat report when the slowdown occurs. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
