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

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Date:   Sat, 18 Jun 2022 08:23:04 +0800
From:   Xing Zhengjun <zhengjun.xing@...ux.intel.com>
To:     Ian Rogers <irogers@...gle.com>,
        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>
Cc:     Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH v6 0/4] Rewrite jevents program in python

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.

> 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