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

[Xing Zhengjun]

Hi Ian,

On 6/18/2022 9:41 AM, Ian Rogers wrote:
> On Fri, Jun 17, 2022 at 5:23 PM Xing Zhengjun
> <zhengjun.xing@xxxxxxxxxxxxxxx> 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 :-)

I test python3.8 and python3.10, both can build successfully.
I also check the "pmu-events.c" generated by both C and python code, 
they are the same.

Tested-by: Zhengjun Xing <zhengjun.xing@xxxxxxxxxxxxxxx>

> Ian
>
> > > v5. Adds a 2>/dev/null as suggested by David Laight
> > >       <David.Laight@xxxxxxxxxx>.
> > > 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@xxxxxxxxxx>). 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@xxxxxxxxxxxxxxx/
> > >       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@xxxxxxxxxx>) and fixes the
> > >       build for python not being present or too old (Suggested-by: Peter
> > >       Zijlstra <peterz@xxxxxxxxxxxxx>/John Garry <john.garry@xxxxxxxxxx>).
> > >
> > > 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

--
Zhengjun Xing