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

From: Xing Zhengjun <zhengjun.xing@linux.intel.com>
To: Ian Rogers <irogers@google.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
	John Garry <john.garry@huawei.com>,
	Kan Liang <kan.liang@linux.intel.com>,
	Andi Kleen <ak@linux.intel.com>, Felix Fietkau <nbd@nbd.name>,
	Qi Liu <liuqi115@huawei.com>, Like Xu <likexu@tencent.com>,
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
	Nick Forrington <nick.forrington@arm.com>,
	Kajol Jain <kjain@linux.ibm.com>,
	James Clark <james.clark@arm.com>,
	Andrew Kilroy <andrew.kilroy@arm.com>,
	"Paul A . Clarke" <pc@us.ibm.com>, Will Deacon <will@kernel.org>,
	Mathieu Poirier <mathieu.poirier@linaro.org>,
	ananth.narayan@amd.com, ravi.bangoria@amd.com,
	santosh.shukla@amd.com, sandipan.das@amd.com,
	Caleb Biggers <caleb.biggers@intel.com>,
	Perry Taylor <perry.taylor@intel.com>,
	Kshipra Bopardikar <kshipra.bopardikar@intel.com>
Cc: Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH v6 0/4] Rewrite jevents program in python
Date: Sat, 18 Jun 2022 08:23:04 +0800	[thread overview]
Message-ID: <d3b39b1c-7d2e-0acd-fa92-8e05a3bad1fb@linux.intel.com> (raw)
In-Reply-To: <20220618000907.433350-1-irogers@google.com>

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@aculab.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@huawei.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@huawei.com>) and fixes the
>      build for python not being present or too old (Suggested-by: Peter
>      Zijlstra <peterz@infradead.org>/John Garry <john.garry@huawei.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