linux-kernel - Re: [PATCH v1 1/2] perf auxtrace: Add 'T' itrace option for timestamp trace

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Message-ID: <20231107141808.GD656098@leoy-yangtze.lan>
Date:   Tue, 7 Nov 2023 22:18:08 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        James Clark <james.clark@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        John Garry <john.g.garry@...cle.com>,
        Will Deacon <will@...nel.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@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>, coresight@...ts.linaro.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/2] perf auxtrace: Add 'T' itrace option for
 timestamp trace

On Tue, Nov 07, 2023 at 12:16:25PM +0200, Adrian Hunter wrote:

[...]

> >>>> "If users know" <- how would users know?  Could the kernel
> >>>> or tools also figure it out?
> >>>
> >>> Adrian, I'm trying to go all the outstanding patches, do you still have
> >>> any issues with this series?
> >>
> >> No, although the question wasn't actually answered.  I presume users
> >> just have to try the 'T' option and see if it helps.
> > 
> > Sometimes, users are software developers in SoC companies, they can
> > know well for the hardware design but are confused why current
> > implementation cannot use timestamp trace.  This is the main reason
> > I sent this patch set.
> > 
> > An example hardware platform is DB410c [1], we know its CoreSight can
> > support timestamp trace, but if without this adding option 'T', we
> > have no chance to use it due to it its CPU arch is prior to Armv8.4.
> 
> perf config might be better than an itrace option, but you decide.

I understand perf config is a better approach due to users don't need
to bother inputting options after set it once.  I will look at it and
respin new patch set.

Thanks for suggestion!

Leo