Re: [PATCH v2 11/27] perf parse-events: Support hardware events inside PMU

[Jin, Yao]

On 3/16/2021 10:04 PM, Jiri Olsa wrote:
> On Tue, Mar 16, 2021 at 09:49:42AM +0800, Jin, Yao wrote:
>
> SNIP
>
> >   Performance counter stats for 'system wide':
> >
> >         136,655,302      cpu_core/branch-instructions/
> >
> >         1.003171561 seconds time elapsed
> >
> > So we need special rules for both cycles and branches.
> >
> > The worse thing is, we also need to process the hardware cache events.
> >
> > # ./perf stat -e cpu_core/LLC-loads/
> > event syntax error: 'cpu_core/LLC-loads/'
> >                                \___ unknown term 'LLC-loads' for pmu 'cpu_core'
> >
> > valid terms: event,pc,edge,offcore_rsp,ldlat,inv,umask,frontend,cmask,config,config1,config2,name,period,percore
> >
> > Initial error:
> > event syntax error: 'cpu_core/LLC-loads/'
> >                                \___ unknown term 'LLC-loads' for pmu 'cpu_core'
> >
> > If we use special rules for establishing all event mapping, that looks too much. :(
>
> hmmm but wait, currently we do not support events like this:
>
>    'cpu/cycles/'
>    'cpu/branches/'
>
> the pmu style accepts only 'events' or 'format' terms within //
>
> we made hw events like 'cycles','instructions','branches' special
> to be used without the pmu
>
> so why do we need to support cpu_code/cycles/ ?
>
> jirka

Actually we have to support pmu style event for hybrid platform.

User may want to enable the events from specified pmus and also with flexible grouping.

For example,

perf stat -e '{cpu_core/cycles/,cpu_core/instructions/}' -e '{cpu_atom/cycles/,cpu_atom/instructions/}'

This usage is common and reasonable. So I think we may need to support pmu style events.

Thanks
Jin Yao