Re: [libvirt-users] problem when get the vm cpu stat

-----Original Message----- From: Michal Privoznik [mailto:mprivozn@redhat.com] Sent: Friday, April 19, 2013 10:53 PM To: Wangkai (Kevin,C) Cc: libvirt-users(a)redhat.com Subject: Re: [libvirt-users] problem when get the vm cpu stat On 19.04.2013 09:40, Wangkai (Kevin,C) wrote: > Hi all, > > > > I try to get vm cpu stat by function "virDomainGetCPUStats", when the vm > > > > Cpu usage is 100%, I can see from the vm shell by "top", when the info > > > > Get by the "virDomainGetCPUStats" show only the "cpu_time" increased, > > > > "user_time" and "system_time" was not changed at all. > > > > Is that correct ? How can I get the vm cpu usage? > > > > nparams = virDomainGetCPUStats(domain, NULL, 0, -1, 1, 0); > > virDomainGetCPUStats(domain, params, nparams, -1, 1, 0); You can gather statistics in similar way that 'top' does. Query current usage in loops and divide increment by time. Something like: nparams = virDomainGetCPUStats(domain, NULL, 0, -1, 1, 0); while (1) { struct timeval now, then; int i, j; gettimeofday(&now, NULL); virDomainGetCPUStats(domain, params_now, nparams, -1, 1, 0); /* some sleep, e.g. 500ms */ usleep(5000); virDomainGetCPUStats(domain, params_then, nparams, -1, 1, 0); gettimeofday(&then, NULL); /* find appropriate i and j */ /* virDomainGetCPUStats is returning time in microseconds IIRC */ float usage_in_percent = (params_then[i] - params_now[j]) / (then.tv_usec - now.tv_usec) / 1000; printf("%f\n", usage_in_percent); }