RE: [Xen-devel] CPU Utilization

["Dave Thompson \(davetho\)" <davetho@xxxxxxxxx>]

> -----Original Message-----
> From: Rob Gardner [mailto:rob.gardner@xxxxxx] 
> Sent: Monday, December 12, 2005 1:23 PM
> To: Dave Thompson (davetho)
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] CPU Utilization
> 
> Dave Thompson (davetho) wrote:
> 
> >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.

Doesn't top's CPU summary line show both?  I thought us=user space,
sy=system, ni=nice, id=idle, hi=hwintr, si=softintr.  So in my
example 1% in user space, 7.3% in system level, 3.3% in h/w intr,
and 15% in soft intr.  Total of 26.6% utilized of which 25.6% is
in kernel.
 
> Perhaps the thing you're running incurs lots of kernel cpu 
> time, but not 
> user time?
> 
> Rob
> 

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