在 2012年3月28日 下午5:02，Osier Yang <jyang@redhat.com> 写道：
On 03/28/2012 01:44 PM, Zhihua Che wrote:
Hi, everyone I'm writing a virtual machine monitor based on libvirt. As I read the api reference, I found I'm confused by some terms.
1, What is cumulative I/O wait CPU time? API reference says that VIR_NODE_CPU_STATS_IOWAIT indicate cumulative I/O wait CPU time. I'm confused by this time. As far as I know, when cpu meets IO wait situation, it will schedule another task, so, how this IO wait time is accounted?
It's from /proc/stat, see man proc (/proc/stat).
2, How do I get VCPU runtime? In my mind, VIR_DOMAIN_CPU_STATS_CPUTIME indicates the physical cpu time consumed by the domain. Is there any API by which I can query virtual CPU running stats in one domain?
See virDomainGetVcpus, though it doesn't returns the usertime and systime seperately, only cputime (usertime + systime) for each vCPU thread.
Regards, Osier
I guess I miss some important points. I find that the cpu_time returned by virDomainGetCPUStats is always increasing despite it's restarted. Precisely, after calling virDomainGetCPUStats, it return a array of virTypedParameter, each element for each cpu. one example is { .fiedl = "cpu_time", .type = 4, .value.ul = 7744142223 } I guess this value is cumulative running time of the domain since it's created? Is that right?