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

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Date:   Wed, 17 Mar 2021 11:06:27 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     "Jin, Yao" <yao.jin@...ux.intel.com>
Cc:     acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        Linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH v2 11/27] perf parse-events: Support hardware events
 inside PMU

On Wed, Mar 17, 2021 at 10:12:03AM +0800, Jin, Yao wrote:
> 
> 
> 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.

sure, but we don't support 'cpu/cycles/' but we support 'cpu/cpu-cycles/'
why do you insist on supporting cpu_core/cycles/ ?

jirka