Re: [PATCH v2 3/3] qemu: Provide virDomainGetCPUStats() implementation for session connection

On Wed, Jan 18, 2023 at 10:58:19AM +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. > > Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; > --- > src/qemu/qemu_driver.c | 52 ++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 50 insertions(+), 2 deletions(-) > > diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c > index 25c681bfd2..cc10dd87e2 100644 > --- a/src/qemu/qemu_driver.c > +++ b/src/qemu/qemu_driver.c > @@ -16006,6 +16006,50 @@ qemuDomainGetMetadata(virDomainPtr dom, >     return ret; > } > > +#define QEMU_CPU_STATS_PROC_TOTAL 3 > + > +static int > +qemuDomainGetCPUStatsProc(virDomainObj *vm, > +                          virTypedParameterPtr params, > +                          unsigned int nparams) The only thing I do not like about this patch is that we would now have both:     static int     qemuDomainGetCPUStatsProc(virDomainObj *vm,                               virTypedParameterPtr params,                               unsigned int nparams) and:     static int     qemuDomainGetStatsCpuProc(virDomainObj *vm,                               virTypedParamList *params) doing almost, but not completely, the same thing.  And there is no nice way to avoid it.  I just haven't noticed in v1, sorry.  Or is there a way to converge at least some of these?