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

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Date:   Tue, 16 Mar 2021 15:04:07 +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 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