linux-kernel - Re: [PATCH v1 0/4] perf cs-etm: Fix synthesizing instruction samples

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Date:   Fri, 1 Nov 2019 10:10:55 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        Mike Leach <mike.leach@...aro.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        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>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Coresight ML <coresight@...ts.linaro.org>,
        Robert Walker <robert.walker@....com>
Subject: Re: [PATCH v1 0/4] perf cs-etm: Fix synthesizing instruction samples

On Thu, Oct 31, 2019 at 11:14:15AM -0600, Mathieu Poirier wrote:
> On Thu, 24 Oct 2019 at 09:15, Leo Yan <leo.yan@...aro.org> wrote:
> >
> > This patch series is to address the issue for synthesizing instruction
> > samples, especially when the instruction sample period is small enough,
> > the current logic cannot synthesize multiple instruction samples within
> > one instruction range packet.
> >
> > To fix this issue, patch 0001 avoids to reset the last branches for
> > every instruction sample; if reset the last branches when every time
> > generate instruction sample, then the later samples in the same range
> > packet cannot use the last branches anymore.
> >
> > Patch 0002 is the main patch to fix the logic for synthesizing
> > instruction samples; it allows to handle different instruction periods.
> >
> > Patch 0003 is an optimization for copying last branches; it only copies
> > last branches once if the instruction samples share the same last
> > branches.
> >
> > Patch 0004 is a minor fix for unsigned variable comparison to zero.
> >
> > To verify my changing for synthesizing instruction samples, I added
> > some logs in the code, and reviewed the output log manually for
> > instuctions samples.  The below commands are tested on DB410c board:
> >
> >   # perf script --itrace=i2
> >   # perf script --itrace=i2li16
> >   # perf inject --itrace=i2il16 -i perf.data -o perf.data.new
> >   # perf inject --itrace=i100il16 -i perf.data -o perf.data.new
> >
> >
> > Leo Yan (4):
> >   perf cs-etm: Continuously record last branches
> >   perf cs-etm: Correct synthesizing instruction samples
> >   perf cs-etm: Optimize copying last branches
> >   perf cs-etm: Fix unsigned variable comparison to zero
> 
> I have reviewed and agree with the changes in this set but won't move
> forward until Mike has looked at patch 2/4.

Thanks a lot for reviewing, Mathieu.

Sorry I forgot to loop Mike in this patch set, and respin patch for v2
and have sent to mailing list.  @Mike, please review patch set v2 as
you received, Thanks!

Thanks,
Leo Yan