linux-kernel - Re: [PATCH 2/3] perf mem: Fix missed p-core mem events on ADL and RPL

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Message-ID: <ZttgvduaKsVn1r4p@x1>
Date: Fri, 6 Sep 2024 17:06:21 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: "Liang, Kan" <kan.liang@...ux.intel.com>
Cc: namhyung@...nel.org, irogers@...gle.com, jolsa@...nel.org,
	adrian.hunter@...el.com, linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] perf mem: Fix missed p-core mem events on ADL and RPL

On Fri, Sep 06, 2024 at 12:08:52PM -0400, Liang, Kan wrote:
> On 2024-09-06 10:17 a.m., Arnaldo Carvalho de Melo wrote:
> > On Thu, Sep 05, 2024 at 03:47:03PM -0400, Liang, Kan wrote:
> >> On 2024-09-05 3:33 p.m., Arnaldo Carvalho de Melo wrote:
> >>> But can we reconstruct the events relationship (group, :S, etc) from
> >>> what we have in the perf.data header?

> >> Do you mean show the group relation in the perf evlist?

> >> $perf mem record sleep 1
> >> [ perf record: Woken up 1 times to write data ]
> >> [ perf record: Captured and wrote 0.027 MB perf.data (10 samples) ]

> >> $perf evlist -g
> >> cpu_atom/mem-loads,ldlat=30/P
> >> cpu_atom/mem-stores/P
> >> {cpu_core/mem-loads-aux/,cpu_core/mem-loads,ldlat=30/}
> >> cpu_core/mem-stores/P
> >> dummy:u

> >> The -g option already did it, although the group modifier looks lost.

> > Right, I can reproduce that, but I wonder if we shouldn't make this '-g'
> > option the default?

> I think the evlist means a list of events. Only outputting the events
> makes sense to me.
> With -g, the extra relationship information is provided.

At first 'perf evlist' showing just the events present in the perf.data
file seems enough, and maybe it should continue like that.

It is just that this relationship is so critical that not showing it by
default looks suboptimal :-\

Perhaps we should add some warning at the end mentioning the special
relationships present and suggest using '-g' to see it?

- Arnaldo