Re: [libvirt-users] data monitored by "virDomainBlockStats" API not consistent with ones reading from /proc/[pid]/io, and corrugated with /proc/diskstats

coperd
Thu, 26 Jun 2014 02:00:55 -0000

On Jun 26, 2014, at 2:50 AM, Eric Blake <eblake@redhat.com> wrote:

> I'm still not clear how you are getting vcpu PID numbers for reading
> from /proc; it's not something that libvirt is currently advertising.

I thought the VM process’s /proc statistics information is exactly the same
as the guest’s behaviour. It turns out to be my misunderstanding.

Each vcpu is a thread of the VM process in qemu implementation, whose
thread id can be obtained by the “-L” option of the “ps” command.  It seems
that I don't mention the vcpu PID. I’m referring to the VM process’s
/proc/$pid.

If running a VM whose image file is located on the local disk, how can i
calculate the disk bandwidth(the percentage, e.g. 40% disk) used by the VM?