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Date:   Sun, 10 Apr 2022 22:35:17 +0800
From:   Leo Yan <leo.yan@linaro.org>
To:     Arnaldo Carvalho de Melo <acme@kernel.org>
Cc:     Namhyung Kim <namhyung@kernel.org>,
        James Clark <james.clark@arm.com>,
        linux-perf-users <linux-perf-users@vger.kernel.org>,
        leo.yan@linaro.com, German Gomez <German.Gomez@arm.com>,
        John Garry <john.garry@huawei.com>,
        Will Deacon <will@kernel.org>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Ravi Bangoria <ravi.bangoria@linux.ibm.com>,
        linux-arm-kernel@lists.infradead.org,
        linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] perf: arm-spe: Fix perf report --mem-mode
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On Sat, Apr 09, 2022 at 12:12:37PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Sat, Apr 09, 2022 at 05:59:41PM +0800, Leo Yan escreveu:
> > On Fri, Apr 08, 2022 at 11:13:09AM -0700, Namhyung Kim wrote:
> > > Hello,
> > > 
> > > On Fri, Apr 8, 2022 at 7:41 AM James Clark <james.clark@arm.com> wrote:
> > > >
> > > > Since commit bb30acae4c4d ("perf report: Bail out --mem-mode if mem info
> > > > is not available") "perf mem report" and "perf report --mem-mode" don't
> > > > allow opening the file unless one of the events has PERF_SAMPLE_DATA_SRC
> > > > set.
> > > >
> > > > SPE doesn't have this set even though synthetic memory data is generated
> > > > after it is decoded. Fix this issue by setting DATA_SRC on SPE events.
> > > > This has no effect on the data collected because the SPE driver doesn't
> > > > do anything with that flag and doesn't generate samples.
> > > >
> > > > Fixes: bb30acae4c4d ("perf report: Bail out --mem-mode if mem info is not available")
> > > > Signed-off-by: James Clark <james.clark@arm.com>
> > > 
> > > Acked-by: Namhyung Kim <namhyung@kernel.org>
> > 
> > Tested-by: Leo Yan <leo.yan@linaro.org>
> > 
> > It's a bit awkward that after the commit bb30acae4c4d we cannot be
> > backward compatible and any old perf data file will be failed to
> > support by 'perf mem report' tool.
> 
> oh well, I think we should put in place a mechanism to run perf record
> before some change, then make sure that a new perf is able to process
> it after a rebuild.
> 
> If its something unsurmountable, then a proper explanation should be
> done with a workaround to process those older files, even if pointing
> out  to the perf version that is able to process the old file.

I will follow up to add a sub test case for Arm SPE with 'perf mem'.

I tried to find possible workround for old perf data files but failed,
the 'perf mem' tool reports error in a very early time so I cannot add
workaround in Arm SPE specific code (e.g. arm_spe_process_auxtrace_info()).
I will check furthermore, as a backup will send a patch to remind
suitable perf version.

A backlog task for me is to setup an automatic testing envoirnment
for daily testing perf on Arm64.  I will setup an automatic testing
for this.

> Anyway, applying this pa tch.

Thanks!

Leo