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

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Date:   Thu, 18 Mar 2021 12:51:45 +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 08:17:52PM +0800, Jin, Yao wrote:

SNIP

> > > 
> > > 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
> > 
> 
> I'm OK to only support 'cpu_core/cpu-cycles/' or 'cpu_atom/cpu-cycles/'. But
> what would we do for cache event?
> 
> 'perf stat -e LLC-loads' is OK, but 'perf stat -e cpu/LLC-loads/' is not supported currently.

ugh, I keep forgetting those ;-)

> 
> For hybrid platform, user may only want to enable the LLC-loads on core CPUs
> or on atom CPUs. That's reasonable. While if we don't support the pmu style
> event, how to satisfy this requirement?
> 
> If we can support the pmu style event, we can also use the same way for
> cpu_core/cycles/. At least it's not a bad thing, right? :)

right, it's probably best to use the pmu/LLC-.../ for this,
I'll check the patch again

jirka