From: "Anand K. Mistry" <amistry@google.com>
To: Andi Kleen <ak@linux.intel.com>
Cc: linux-perf-users@vger.kernel.org,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Ingo Molnar <mingo@redhat.com>, Jiri Olsa <jolsa@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Namhyung Kim <namhyung@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] perf record: Use an eventfd to wakeup when done
Date: Mon, 25 May 2020 11:43:00 +1000 [thread overview]
Message-ID: <CAATStaOY+JJ7mXWRwfXWuR_imhwsv=PecKSWiuZUetHTcz3EXg@mail.gmail.com> (raw)
In-Reply-To: <87a71y93lr.fsf@linux.intel.com>
On Sat, 23 May 2020 at 23:35, Andi Kleen <ak@linux.intel.com> wrote:
>
> Anand K Mistry <amistry@google.com> writes:
> > }
> >
> > + done_fd = eventfd(0, EFD_NONBLOCK);
>
> This will make perf depend on a recent glibc or other library
> that implements eventfd. Wouldn't surprise me if some kind
> of build time check is needed for this to pass all of Arnaldo's
> built tests.
Looks like Arnaldo made that change when merging:
https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/commit/?h=perf/core&id=e9db221d37f91409040cf7f3fbed08b44e055ae9
This makes me curious. How old a kernel should modern tools support?
From the man page, eventfd was added in 2.6.22 (and eventfd2 in
2.6.27), which was 2007 (or 2008 for eventfd2) and glibc-2.8 which was
2008. I understand the kernel's policy of never breaking userspace,
but what about userspace tools?
>
>
> -Andi
--
Anand K. Mistry
Software Engineer
Google Australia
prev parent reply other threads:[~2020-05-25 1:43 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-08 4:56 [PATCH] perf record: Use an eventfd to wakeup when done Anand K Mistry
2020-05-11 11:28 ` Jiri Olsa
2020-05-12 4:59 ` Anand K Mistry
2020-05-12 12:12 ` Jiri Olsa
2020-05-12 14:12 ` Arnaldo Carvalho de Melo
2020-05-13 2:30 ` Anand K. Mistry
2020-05-13 2:20 ` [PATCH v3] " Anand K Mistry
2020-05-13 11:39 ` Jiri Olsa
2020-05-13 14:03 ` Arnaldo Carvalho de Melo
2020-05-20 15:47 ` Arnaldo Carvalho de Melo
2020-05-23 13:34 ` Andi Kleen
2020-05-25 1:43 ` Anand K. Mistry [this message]
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