linux-kernel - Re: [PATCH v6 0/4] Rewrite jevents program in python

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Message-ID: <CAP-5=fUVWsVz2WguxDgiAEqG=eVAmJ+qkKDndDcfancsd8V2+A@mail.gmail.com>
Date:   Fri, 17 Jun 2022 18:41:50 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Xing Zhengjun <zhengjun.xing@...ux.intel.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        John Garry <john.garry@...wei.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>, Felix Fietkau <nbd@....name>,
        Qi Liu <liuqi115@...wei.com>, Like Xu <likexu@...cent.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Nick Forrington <nick.forrington@....com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        James Clark <james.clark@....com>,
        Andrew Kilroy <andrew.kilroy@....com>,
        "Paul A . Clarke" <pc@...ibm.com>, Will Deacon <will@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        ananth.narayan@....com, ravi.bangoria@....com,
        santosh.shukla@....com, sandipan.das@....com,
        Caleb Biggers <caleb.biggers@...el.com>,
        Perry Taylor <perry.taylor@...el.com>,
        Kshipra Bopardikar <kshipra.bopardikar@...el.com>,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH v6 0/4] Rewrite jevents program in python

On Fri, Jun 17, 2022 at 5:23 PM Xing Zhengjun
<zhengjun.xing@...ux.intel.com> wrote:
>
> Hi Ian,
>
> On 6/18/2022 8:09 AM, Ian Rogers wrote:
> > New architectures bring new complexity, such as Intel's hybrid
> > models. jevents provides an alternative to specifying events in the
> > kernel and exposing them through sysfs, however, it is difficult to
> > work with. For example, an error in the json input would yield an
> > error message but no json file or location. It is also a challenge to
> > update jsmn.c given its forked nature.
> >
> > The changes here switch from jevents.c to a rewrite in python called
> > jevents.py. This means there is a build time dependency on python, but
> > such a dependency already exists for asciidoc (used to generate perf's
> > man pages). If the build detects that python isn't present or is older
> > than version 3.6 (released Dec. 2016) then an empty file is
> > substituted for the generated one.
> >
> > A challenge with this code is in avoiding regressions. For this reason
> > the jevents.py produces identical output to jevents.c, validated with a
> > test script and build target.
> >
> > v6. Fixes an annotation and use of removesuffix that aren't present in
> >      Python 3.6. Linter issues are also fixed.The code was tested on
> >      Python 3.6 and 3.8 with docker.
>
> I just test it, now it can be built successfully with python 3.8.

Great! Tested-by/Reviewed-by/Acked-by always welcome :-)

Ian

> > v5. Adds a 2>/dev/null as suggested by David Laight
> >      <David.Laight@...lab.com>.
> > v4. Fixes the build for systems with python2 installed by adding a
> >      patch that makes python3 the preferred python (Reported-by: John
> >      Garry <john.garry@...wei.com>). It also fixes a bash-ism in the
> >      jevents-test.sh and fixes the handling of an empty string for a
> >      metric BriefDescription as one was added for sapphirerapids in the
> >      metric Execute.
> > v3. Updates the patches for merged changes (on
> >      acme/tmp.perf/core). Re-runs all comparisons to make sure the
> >      generated pmu-events.c isn't altered at all by this change. Adds
> >      the jevents.c ExtSel fix in:
> >      https://lore.kernel.org/lkml/20220525140410.1706851-1-zhengjun.xing@linux.intel.com/
> >      Bumps the python version from 3.5 to 3.6, as f-strings weren't
> >      introduced until 3.6.
> >
> > v2. Fixes the build for architectures that don't have pmu-events json
> >      (Suggested-by: John Garry <john.garry@...wei.com>) and fixes the
> >      build for python not being present or too old (Suggested-by: Peter
> >      Zijlstra <peterz@...radead.org>/John Garry <john.garry@...wei.com>).
> >
> > Ian Rogers (4):
> >    perf python: Prefer python3
> >    perf jevents: Add python converter script
> >    perf jevents: Switch build to use jevents.py
> >    perf jevents: Remove jevents.c
> >
> >   tools/perf/Makefile.config               |   27 +-
> >   tools/perf/Makefile.perf                 |   16 +-
> >   tools/perf/pmu-events/Build              |   15 +-
> >   tools/perf/pmu-events/empty-pmu-events.c |   21 +
> >   tools/perf/pmu-events/jevents.c          | 1342 ----------------------
> >   tools/perf/pmu-events/jevents.py         |  409 +++++++
> >   tools/perf/pmu-events/jsmn.h             |   68 --
> >   tools/perf/pmu-events/json.c             |  162 ---
> >   tools/perf/pmu-events/json.h             |   39 -
> >   9 files changed, 465 insertions(+), 1634 deletions(-)
> >   create mode 100644 tools/perf/pmu-events/empty-pmu-events.c
> >   delete mode 100644 tools/perf/pmu-events/jevents.c
> >   create mode 100755 tools/perf/pmu-events/jevents.py
> >   delete mode 100644 tools/perf/pmu-events/jsmn.h
> >   delete mode 100644 tools/perf/pmu-events/json.c
> >   delete mode 100644 tools/perf/pmu-events/json.h
> >
>
> --
> Zhengjun Xing