Re: [PATCH v3 0/3] Rewrite jevents program in python

[Ian Rogers <irogers@google.com>]

On Wed, Jun 1, 2022 at 9:17 AM John Garry <john.garry@huawei.com> wrote:
>
> On 27/05/2022 19:54, 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.
> >
>
> Hi Ian,
>
> I still see this:
>
> ...
> Makefile.config:906: Python interpreter too old (older than 3.6)
> disabling jevent generation
> Makefile.config:939: Old version of libbfd/binutils things like PE
> executable profiling will not be available
> Makefile.config:1127: No openjdk development package found, please
> install JDK package, e.g. openjdk-8-jdk, java-1.8.0-openjdk-devel
>
> Auto-detecting system features:
> ...                         dwarf: [ on  ]
> ...            dwarf_getlocations: [ on  ]
> ...                         glibc: [ on  ]
> ...                        libbfd: [ OFF ]
> ...                libbfd-buildid: [ OFF ]
> ...                        libcap: [ on  ]
> ...                        libelf: [ on  ]
> ...                       libnuma: [ on  ]
> ...        numa_num_possible_cpus: [ on  ]
> ...                       libperl: [ on  ]
> ...                     libpython: [ on  ]
> ...                     libcrypto: [ on  ]
> ...                     libunwind: [ on  ]
> ...            libdw-dwarf-unwind: [ on  ]
> ...                          zlib: [ on  ]
> ...                          lzma: [ on  ]
> ...                     get_cpuid: [ on  ]
> ...                           bpf: [ on  ]
> ...                        libaio: [ on  ]
> ...                       libzstd: [ on  ]
> ...        disassembler-four-args: [ on  ]
>
>
> make[3]: Nothing to be done for 'install_headers'.
> john@localhost:~/acme/tools/perf> python --version
> Python 3.6.12
>
> I need to figure out what is going wrong...

Thanks for testing John! Could you try adding something like this:
```
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 9538d737d655..c23f39e21a70 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -901,6 +901,8 @@ ifneq ($(NO_JEVENTS),1)
    NO_JEVENTS := 1
  else
    # jevents.py uses f-strings present in Python 3.6 released in Dec. 2016.
+    PYTHON_VERSION=$(shell $(PYTHON) -c 'import sys;print(sys.version_info)')
+    $(error $(PYTHON_VERSION))
    JEVENTS_PYTHON_GOOD := $(shell $(PYTHON) -c 'import sys;print("1"
if(sys.version_info.major >=
3 and sys.version_info.minor >= 6) else "0")')
    ifneq ($(JEVENTS_PYTHON_GOOD), 1)
      $(warning Python interpreter too old (older than 3.6) disabling
jevent generation)
```
You can also specify which python you want on the make command line,
for example adding PYTHON=`which python` at the end of your make
command.

Thanks,
Ian

> Thanks,
> John
>
> > 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 (3):
> >    perf jevents: Add python converter script
> >    perf jevents: Switch build to use jevents.py
> >    perf jevents: Remove jevents.c
> >
> >   tools/perf/Makefile.config               |   19 +
> >   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         |  392 +++++++
> >   tools/perf/pmu-events/jsmn.h             |   68 --
> >   tools/perf/pmu-events/json.c             |  162 ---
> >   tools/perf/pmu-events/json.h             |   39 -
> >   9 files changed, 444 insertions(+), 1630 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
> >
>