Messages in this thread | | | Date | Tue, 17 May 2022 11:32:04 +0100 | Subject | Re: [PATCH v2 6/7] perf jevents: Switch build to use jevents.py | From | John Garry <> |
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On 13/05/2022 16:58, Ian Rogers wrote: > On Fri, May 13, 2022 at 8:38 AM John Garry <john.garry@huawei.com> wrote: >> >> On 11/05/2022 22:15, Ian Rogers wrote: >>> # jevents.py uses os.scandir and type hints present in Python 3.5 released in Sept. 2015. >>> + JEVENTS_PYTHON_GOOD := $(shell $(PYTHON) -c 'import sys;print("1" if(sys.version_info.major >= 3 and sys.version_info.minor >= 5) else "0")') >> >> I think that many - like me - will have python 2.7, so now will find no >> pmu-events generated any longer after missing this message in the build :( >> >> Maybe many will have python >= 3.5 - but I don't know... > > So Python 2 has been end-of-life for over 2 years now: > https://www.python.org/doc/sunset-python-2/ > There have been a number of LKML patches upgrading python to version 3. > > Python 3.5 has some very nice features of os.scandir and type hints, > so if I set the bar lower than this it hurts the code quality. It is > also at least 6 years old at this point, and so hopefully not > unreasonable for a distribution to have picked it up :-) Looking at > the change to C11 thread: > https://lore.kernel.org/lkml/20220228103142.3301082-1-arnd@kernel.org/ > It seems the motivation for picking a language version is the features > it provides and compatibility. If we choose pre-Python 3.5 we get more > compatibility but we lose language features. > > My feeling is that we shouldn't need to support things that are no > longer maintained (like Python 2) but I'm less clear if Python 3.5 is > sufficiently compatible for everyone's needs. I kind of hope so, hence > making the patches this way.
Fine, I just think that you need to make this transition as seamless as possible, otherwise it can be judged as a regression.
For example, I have now python 3.6 (default) and 2.7 but it still doesn't seem to work:
john@localhost:~/acme/tools/perf> make BUILD: Doing 'make -j4' parallel build Warning: Kernel ABI header at 'tools/include/linux/coresight-pmu.h' differs from latest version at 'include/linux/coresight-pmu.h' diff -u tools/include/linux/coresight-pmu.h include/linux/coresight-pmu.h Makefile.config:593: No sys/sdt.h found, no SDT events are defined, please install systemtap-sdt-devel or systemtap-sdt-dev Makefile.config:871: Python interpreter too old (older than 3.5) disabling jevent generation Makefile.config:904: Old version of libbfd/binutils things like PE executable profiling will not be available Makefile.config:1092: 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 john@localhost:~/acme/tools/perf>
which I need to figure out...
> >> > + ifneq ($(JEVENTS_PYTHON_GOOD), 1) >> > + $(warning Python interpreter too old (older than 3.5) disabling >> jevent generation) >> > + NO_JEVENTS := 1 >> >> It is possible to flip NO_JEVENTS to be JEVENTS, i.e. no >> double-negatives, like NO_JEVENTS := 0 > > Agreed that double negatives are bad. The NO_... pattern is kind of > throughout the make files and build files. I preferred the NO_... for > consistency but if there's a consensus I'm happy to change. >
I have no strong preference. I just find that double negatives boggle the mind.
Thanks, john
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