linux-kernel - Re: [PATCH v4 0/6] perf arm-spe: Enable timestamp

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Date:   Thu, 15 Apr 2021 22:56:22 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     James Clark <james.clark@....com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Al Grant <Al.Grant@....com>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <will@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Dave Martin <Dave.Martin@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 0/6] perf arm-spe: Enable timestamp

On Thu, Apr 15, 2021 at 05:43:24PM +0300, James Clark wrote:
> Hi Leo,
> 
> I was looking at testing this on N1SDP and I thought I would try the round trip with perf inject and
> then perf report but saw that perf inject with SPE always results in an error (unrelated to your change)
> 
> 	 -> ./perf report -i per-thread-spe-time.inject.data
> 	0x1328 [0x8]: failed to process type: 9 [Bad address]
> 	Error:
> 	failed to process sample
> 
> 
> Do you have any test suggestions other than looking at the raw data?

Good catching!  I didn't use inject mode for Arm SPE before (it's not
not like Arm CoreSight for instruction sample, or SPE's branch sample
is statistical so we cannot generate branch samples based on accurate
interval).

For the debugging, it's good to use "git grep" to search "Bad address"
to check where the error happens, and can use gdb.  I personally think
it's possible to go back to check the sythenization flow, simply to
say, it might have problems when inject samples but not in the
decoding flow.

Thanks,
Leo