Re: [PATCH] qemu: Provide virDomainGetCPUStats() implementation for session connection

On Tue, Jan 17, 2023 at 01:44:44PM +0100, Michal Privoznik wrote: > We have virDomainGetCPUStats() API which offers querying > statistics on host CPU usage by given guest. And it works in two > modes: getting overall stats (@start_cpu == -1, @ncpus == 1) or > getting per host CPU usage. > > For the QEMU driver it is implemented by looking into values > stored in corresponding cpuacct CGroup controller. Well, this > works for system instances, where libvirt has permissions to > create CGroups and place QEMU process into them. But it does not > fly for session connection, where no CGroups are set up. > > Fortunately, we can do something similar to v8.8.0-rc1~95 and use > virProcessGetStatInfo() to fill the overall stats. Unfortunately, > I haven't found any source of per host CPU usage, so we just > continue throwing an error in that case. > Looks ok, but there's one thing that's bothering me a bit.  On non-Linux platforms this API would start to work and returning zeros.  Could that be fixed somehow in a nice fashion or should I treat that as a non-issue?