linux-kernel - Re: [PATCH v4 0/5] perf cs-etm: Fix synthesizing instruction samples

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Message-ID: <20200218184934.GA11448@xps15>
Date:   Tue, 18 Feb 2020 11:49:34 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Leo Yan <leo.yan@...aro.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Robert Walker <robert.walker@....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@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Coresight ML <coresight@...ts.linaro.org>
Subject: Re: [PATCH v4 0/5] perf cs-etm: Fix synthesizing instruction samples

On Thu, Feb 13, 2020 at 05:41:59PM +0800, Leo Yan wrote:
> This patch series is to address issues 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.
> 
> Patch 0001 is to swap packets for instruction samples, so this allow
> option '--itrace=iNNN' can work well.
> 
> Patch 0002 avoids to reset the last branches for every instruction
> sample; if reset the last branches for every time generating sample, the
> later samples in the same range packet cannot use the last branches
> anymore.
> 
> Patch 0003 is the fixing for handling different instruction periods,
> especially for small sample period.
> 
> Patch 0004 is an optimization for copying last branches; it only copies
> last branches once if the instruction samples share the same last
> branches.
> 
> Patch 0005 is a minor fix for unsigned variable comparison to zero.
> 
> This patch set has been rebased on the latest perf/core branch; and
> verified on Juno board with below commands:
> 
>   # perf script --itrace=i2
>   # perf script --itrace=i2il16
>   # perf inject --itrace=i2il16 -i perf.data -o perf.data.new
>   # perf inject --itrace=i100il16 -i perf.data -o perf.data.new
> 
> Changes from v3:
> * Refactored patch 0001 with new function cs_etm__packet_swap() (Mike);
> * Refined instruction sample generation flow with single while loop,
>   which completely uses Mike's suggestions (Mike);
> * Added Mike's review tags for patch 01/02/04/05.
> 
> Changes from v2:
> * Added patch 0001 which is to fix swapping packets for instruction
>   samples;
> * Refined minor commit logs and comments;
> * Rebased on the latest perf/core branch.
> 
> Changes from v1:
> * Rebased patch set on perf/core branch with latest commit 9fec3cd5fa4a
>   ("perf map: Check if the map still has some refcounts on exit").
> 
> 
> 
> Leo Yan (5):
>   perf cs-etm: Swap packets for instruction samples
>   perf cs-etm: Continuously record last branch
>   perf cs-etm: Correct synthesizing instruction samples
>   perf cs-etm: Optimize copying last branches
>   perf cs-etm: Fix unsigned variable comparison to zero

For all the patches in this set:

Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>

Unless Arnaldo says otherwise, I suggest you send a new V5 with Mike's RB for
patch 3/5 and mine for all of them.  That way he doesn't have to edit the
patches when applying them.

Thanks,
Mathieu

> 
>  tools/perf/util/cs-etm.c | 157 +++++++++++++++++++++++++++------------
>  1 file changed, 111 insertions(+), 46 deletions(-)
> 
> -- 
> 2.17.1
>