linux-kernel - Re: [PATCH v2 1/4] perf header: Write out even empty die_cpus

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Message-ID: <CAP-5=fXsO2i6UE6FrQFLOyJP4xbH1E0-2W5b1ejN=MsGs0d0QQ@mail.gmail.com>
Date: Mon, 16 Dec 2024 08:56:47 -0800
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	Kan Liang <kan.liang@...ux.intel.com>, Sun Haiyong <sunhaiyong@...ngson.cn>, 
	Yanteng Si <siyanteng@...ngson.cn>, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/4] perf header: Write out even empty die_cpus_list

On Sun, Dec 15, 2024 at 5:46 PM Ian Rogers <irogers@...gle.com> wrote:
>
> Reading the CPU topology is tolerant to the dies_cpus_list being
> missing by using the feature's size in the data file/pipe. However,
> the feature's size is just the header size and may be
> unaligned. Making the header size aligned breaks detecting a missing
> die_cpus_list. To allow the header size to be aligned always write the
> die_cpus_lists even if empty.
>
> Signed-off-by: Ian Rogers <irogers@...gle.com>

This change breaks the "Session topology" test on ARM with "Cpu map -
Die ID doesn't match" . One die id is -1 and the other is 0. I'll look
into addressing this in v3.

Thanks,
Ian