[libvirt] [PATCH 1/1] perf: add more perf events support

[Ren, Qiaowei]

> -----Original Message-----
> From: libvir-list-bounces at redhat.com [mailto:libvir-list-bounces at redhat.com]
> On Behalf Of Ren, Qiaowei
> Sent: Sunday, June 12, 2016 10:14 AM
> To: Peter Krempa <pkrempa at redhat.com>
> Cc: libvir-list at redhat.com
> Subject: Re: [libvirt] [PATCH 1/1] perf: add more perf events support
> 
> > > diff --git a/include/libvirt/libvirt-domain.h
> > > b/include/libvirt/libvirt-domain.h
> > > index cba4fa5..99c4c48 100644
> > > --- a/include/libvirt/libvirt-domain.h
> > > +++ b/include/libvirt/libvirt-domain.h
> > > @@ -1928,6 +1928,45 @@ void
> > virDomainStatsRecordListFree(virDomainStatsRecordPtr *stats);
> > >   */
> > >  # define VIR_PERF_PARAM_MBML "mbml"
> >
> > [...]
> >
> > > +/**
> > > + * VIR_PERF_PARAM_INSTRUCTIONS:
> > > + *
> > > + * Macro for typed parameter name that represents instructions perf
> > > + * event which can be used to measure the amount of instructions
> > > + * by applications running on the platform. It corresponds to the
> > > + * "perf.instructions" field in the *Stats APIs.
> >
> > I'm not sure if I understand the implications and usability of this stat parameter.
> > Could you elaborate on how this can be used?
> >
> > > + */
> > > +# define VIR_PERF_PARAM_INSTRUCTIONS "instructions"
> > > +
> > > +/**
> > > + * VIR_PERF_PARAM_CPU_CYCLES:
> > > + *
> > > + * Macro for typed parameter name that represents cpu_cycles perf
> > > +event
> > > + * which can be used to measure how many cycles one instruction needs.
> > > + * It corresponds to the "perf.cpu_cycles" field in the *Stats APIs.
> >
> > And same for this. I don't really see how this can be used.
> >
> 
> Peter, thanks for your feedback!
> 
> Instructions and cycles can be used to gain IPC (Instructions Per Clock, =
> Instructions/Cycles), and a low IPC ratio indicates the code of the process makes
> poor use of the CPU.
> 

Peter, do you have any other comments about this patch?

Thanks,
Qiaowei