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From:   Ian Rogers <irogers@google.com>
Date:   Wed, 11 May 2022 07:00:35 -0700
Message-ID: <CAP-5=fXjW7L+dfW9wfHuG70Ne6rWAHwx1krQUTiB7xEyJ-rmMA@mail.gmail.com>
Subject: Re: [PATCH 0/7] Rewrite jevents program in python
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     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>,
        Zhengjun Xing <zhengjun.xing@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>,
        Stephane Eranian <eranian@google.com>
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On Wed, May 11, 2022 at 6:56 AM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Wed, May 11, 2022 at 06:50:59AM -0700, Ian Rogers wrote:
> > On Wed, May 11, 2022 at 12:35 AM Peter Zijlstra <peterz@infradead.org> wrote:
> > >
> > > On Wed, May 11, 2022 at 12:01:26AM -0700, Ian Rogers wrote:
> > >
> > > > 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).
> > >
> > > You mean just building perf (not the docs) will now require snake stuff?
> > >
> > > That's very tedious :/ I don't typically have snakes on my machines.
> >
> > Hi Peter,
> >
> > You're right that after these changes python is a build requirement
> > for jevents. We could keep the C code around for the case that python
> > isn't there, but I want to do things like remove the string
> > relocations, sort the events by name so we don't linearly search, etc.
> > which would be a massive chore to keep alive on the C side. An
> > alternative would be to have an empty pmu-events.c file that is used
> > for this case. If you wanted to keep things in C and have jevents like
> > event names, you could use the empty version and link in libpfm4.
>
> I'm not normally linking to libpfm4. All I really care about is that I
> can still build a bare cli perf (not even tui). If all the snake stuff
> is purely optional and it just disables some features, but I do get a
> perf out at the end, then I'm all good.
>

Great! I'll add a conditional "empty" file version for this case.

Thanks,
Ian