Re: [Xen-devel] CPU Utilization

Rob Gardner
Mon, 12 Dec 2005 19:23:19 -0000

>I have a question concerning the CPU utilization number provided by
>the ''xm top'' command in xen 3.0.  I''ve noticed
that if I run a TCP
>performance tool on domain 0 which simply receives and echos back
>a TCP stream, the output of ''xm top'' during the test does
not match
>up with the output of ''top'' on domain 0 in terms of CPU
utilization
>(nor with the CPU utilization computed by the test program).
>
>...
>
>Any idea why these displays disagree?
>
>

Top shows cpu usage for user processes in dom0, while xm top shows cpu
usage for the domain, which includes cpu time spent in the dom0 kernel.
Perhaps the thing you''re running incurs lots of kernel cpu time, but
not
user time?

Rob