On 02/27/2013 08:25 PM, 张章 wrote:
>
> Hi,all
> I want to get a relatively accurate cpu usage of a domain. I have a few
> questions about virDomainGetInfo: struct virDomainInfo{ unsigned char
> state : //the running state, one of virDomainState unsigned long maxMem
> :// the maximum memory in KBytes allowed unsigned long memory :// the
> memory in KBytes used by the domain unsigned short nrVirtCpu :// the number
> of virtual CPUs for the domain unsigned long long cpuTime : //the CPU time
> used in nanoseconds }
> If a domain is assigned to 4 vcpus and my machine has 6 physical cores, then
> the cpuTime in virDomainInfo should be the sum of cpu time of the 4 vcpus.
> When I want to calculate the cpu usage, which of the following is more
> accurate? 1/4 * cpu time / total time or 4/6 * cpu time / total time
> or just cpu time / total time [Can you please convince your mailer to wrap long lines, and use proper line breaks when quoting code, so that your mail is legible?] At this point, I'd suggest the best way of knowing what times are returned is checking the source code; but patches to make the documentation more obvious for the next person would be appreciated. If you want more statistics, which might provide you with more accuracy, you might also be interested in looking at the virDomainGetCPUStats. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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