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

From: John Garry
Date: Tue Jun 14 2022 - 11:50:07 EST

On 01/06/2022 23:43, Ian Rogers wrote:
On Wed, Jun 1, 2022 at 9:17 AM John Garry<john.garry@xxxxxxxxxx> 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)
```

That gives:

Makefile.config:459: No libdw DWARF unwind found, Please install elfutils-devel/libdw-dev >= 0.158 and/or set LIBDW_DIR
Makefile.config:464: No libdw.h found or old libdw.h found or elfutils is older than 0.138, disables dwarf support. Please install new elfutils-devel/libdw-dev
Makefile.config:617: DWARF support is off, BPF prologue is disabled
Makefile.config:667: No debug_frame support found in libunwind-aarch64
Makefile.config:738: No debug_frame support found in libunwind
Makefile.config:906: *** sys.version_info(major=2, minor=7, micro=13, releaselevel='final', serial=0).Stop.
Makefile.perf:239: recipe for target 'sub-make' failed
make[1]: *** [sub-make] Error 2
Makefile:69: recipe for target 'all' failed
make: *** [all] Error 2
john@debian:~/linux/tools/perf$ python --version
Python 3.6.9
john@debian:~/linux/tools/perf$

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.

diff -u tools/perf/trace/beauty/include/linux/socket.h include/linux/socket.h
Makefile.config:259: *** which python-config not found. Stop.
Makefile.perf:239: recipe for target 'sub-make' failed
make[1]: *** [sub-make] Error 2
Makefile:69: recipe for target 'all' failed
make: *** [all] Error 2
john@debian:~/linux/tools/perf$

JFYI, this is my alternatives:

sudo update-alternatives --config python
There are 3 choices for the alternative python (providing /usr/bin/python).

Selection Path Priority Status
------------------------------------------------------------
0 /usr/local/bin/python3.6 50 auto mode
1 /usr/bin/python2.7 1 manual mode
2 /usr/bin/python3.5 2 manual mode
* 3 /usr/local/bin/python3.6 50 manual mode

Press <enter> to keep the current choice[*], or type selection number:


Can someone else try this? Arnaldo?

Sorry for being useless with this....