linux-kernel - Re: [PATCH] perf cs-etm: Delay decode of non-timeless data until cs_etm__flush

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Message-ID: <YN34LlxuaNo60CGu@kernel.org>
Date:   Thu, 1 Jul 2021 14:15:26 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     James Clark <james.clark@....com>, coresight@...ts.linaro.org,
        leo.yan@...aro.org, al.grant@....com, branislav.rankov@....com,
        denik@...omium.org, suzuki.poulose@....com,
        anshuman.khandual@....com, Mike Leach <mike.leach@...aro.org>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf cs-etm: Delay decode of non-timeless data until
 cs_etm__flush_events()

Em Mon, Jun 14, 2021 at 09:54:42AM -0600, Mathieu Poirier escreveu:
> On Wed, Jun 09, 2021 at 04:04:20PM +0300, James Clark wrote:
> > Currently, timeless mode starts the decode on PERF_RECORD_EXIT, and
> > non-timeless mode starts decoding on the fist PERF_RECORD_AUX record.
> > 
> > This can cause the "data has no samples!" error if the first
> > PERF_RECORD_AUX record comes before the first (or any relevant)
> > PERF_RECORD_MMAP2 record because the mmaps are required by the decoder
> > to access the binary data.
> > 
> > This change pushes the start of non-timeless decoding to the very end of
> > parsing the file. The PERF_RECORD_EXIT event can't be used because it
> > might not exist in system-wide or snapshot modes.

<SNIP>

> This looks good to me but I'd like to have other people testing it.

So Leo reviewed and tested this, I'm taking your "looks good to me" as
an Acked-by, as per Documentation/process/submitting-patches.rst.

- Arnaldo
 
> Thanks,
> Mathieu