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

From: Arnaldo Carvalho de Melo <[email-masked]>
Date: Tue, 18 Feb 2020 16:30:11 -0300

Em Tue, Feb 18, 2020 at 11:49:34AM -0700, Mathieu Poirier escreveu:
> 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 <[email-masked]>
> 
> 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.

Yeah, that would make things easier for me, always appreciated.

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

-- 

- Arnaldo

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