From: Jiri Olsa <jolsa@redhat.com>
To: Ian Rogers <irogers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
lkml <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Michael Petlan <mpetlan@redhat.com>,
Song Liu <songliubraving@fb.com>,
"Frank Ch. Eigler" <fche@redhat.com>,
Stephane Eranian <eranian@google.com>,
Alexey Budankov <alexey.budankov@linux.intel.com>,
Andi Kleen <ak@linux.intel.com>,
Adrian Hunter <adrian.hunter@intel.com>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Yonghong Song <yhs@fb.com>
Subject: Re: [PATCH 02/26] perf: Introduce mmap3 version of mmap event
Date: Mon, 14 Sep 2020 22:07:11 +0200 [thread overview]
Message-ID: <20200914200711.GS1714160@krava> (raw)
In-Reply-To: <CAP-5=fUansxK_as61teHsLyRQu3Zu5UE-+SDqWVYGhSz36uCzQ@mail.gmail.com>
On Mon, Sep 14, 2020 at 10:08:01AM -0700, Ian Rogers wrote:
SNIP
> >
> > Using one of the MISC bits to resolve the union. Might actually bring
> > benefit to everyone. Us normal people get to have a smaller MMAP record,
> > while the buildid folks can have it too.
> >
> > Even more extreme would be using 2 MISC bits and allowing the union to
> > be 0 sized for anon.
> >
> > That said; I have the nagging feeling there were unresolved issues with
> > mmap2, but I can't seem to find any relevant emails on it :/ My
> > google-fu is weak today.
>
> Firstly, thanks Jiri for this really useful patch set for our
> use-cases! Some thoughts:
>
> One issue with mmap2 events at the moment is that they happen "after"
> the mmap is performed. This allows the mapped address to be known but
> has the unfortunate problem of causing mmap events to get "extended"
> due to adjacent vmas being merged. There are some workarounds like
> commit c8f6ae1fb28d (perf inject jit: Remove //anon mmap events).
> Perhaps these events can switch to reporting the length the mmap
> requested rather than the length of the vma?
seems like separate feature, perhaps we could use another MISC bit for that?
>
> I could imagine that changes here could be interesting to folks doing
> CHERI or hypervisors, for example, they may want more address bits.
>
> BPF has stack traces with elements of buildid + offset. Using these in
> perf samples would avoid the need for mmap events, synthesis, etc. but
> at the cost of larger and possibly slower stack traces. Perhaps we
> should just remove the idea of mmap events altogether?
hm, we also need mmap events to resolve PERF_SAMPLE_IP, right?
also not sure how would we do that for dwarf unwind, and perhaps
there are some other places.. c2c data address resolving?
thanks,
jirka
next prev parent reply other threads:[~2020-09-14 20:07 UTC|newest]
Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-13 21:02 [RFC 00/26] perf: Add mmap3 support Jiri Olsa
2020-09-13 21:02 ` [PATCH 01/26] bpf: Move stack_map_get_build_id into lib Jiri Olsa
2020-09-14 6:09 ` Song Liu
2020-09-13 21:02 ` [PATCH 02/26] perf: Introduce mmap3 version of mmap event Jiri Olsa
2020-09-14 5:38 ` Namhyung Kim
2020-09-14 6:20 ` Song Liu
2020-09-14 19:38 ` Jiri Olsa
2020-09-14 15:28 ` Arnaldo Carvalho de Melo
2020-09-14 16:35 ` peterz
2020-09-14 17:08 ` Ian Rogers
2020-09-14 20:07 ` Jiri Olsa [this message]
2020-09-15 5:49 ` Adrian Hunter
2020-09-14 19:38 ` Jiri Olsa
2020-09-14 19:39 ` Jiri Olsa
2020-09-14 22:00 ` Arnaldo Carvalho de Melo
2020-09-15 5:39 ` Adrian Hunter
2020-09-14 19:38 ` Jiri Olsa
2020-09-15 2:54 ` Namhyung Kim
2020-09-14 6:41 ` Stephane Eranian
2020-09-14 9:08 ` peterz
2020-09-14 15:32 ` Arnaldo Carvalho de Melo
2020-09-14 17:26 ` Stephane Eranian
2020-09-14 19:56 ` Jiri Olsa
2020-09-15 0:03 ` Ian Rogers
2020-09-14 15:31 ` Arnaldo Carvalho de Melo
2020-09-14 19:50 ` Jiri Olsa
2020-09-14 22:38 ` Arnaldo Carvalho de Melo
2020-09-14 19:45 ` Jiri Olsa
2020-09-14 9:36 ` peterz
2020-09-13 21:02 ` [PATCH 03/26] tools headers uapi: Sync tools/include/uapi/linux/perf_event.h Jiri Olsa
2020-09-14 5:39 ` Namhyung Kim
2020-09-13 21:02 ` [PATCH 04/26] perf tools: Add filename__decompress function Jiri Olsa
2020-09-14 15:35 ` Arnaldo Carvalho de Melo
2020-09-14 20:43 ` Jiri Olsa
2020-09-17 18:54 ` Arnaldo Carvalho de Melo
2020-09-18 10:51 ` Jiri Olsa
2020-09-13 21:02 ` [PATCH 05/26] perf tools: Add build_id__is_defined function Jiri Olsa
2020-09-14 5:44 ` Namhyung Kim
2020-09-14 16:03 ` Arnaldo Carvalho de Melo
2020-09-14 20:49 ` Jiri Olsa
2020-09-14 20:47 ` Jiri Olsa
2020-09-14 21:51 ` Arnaldo Carvalho de Melo
2020-09-13 21:02 ` [PATCH 06/26] perf tools: Add support to read build id from compressed elf Jiri Olsa
2020-09-14 16:04 ` Arnaldo Carvalho de Melo
2020-09-14 20:49 ` Jiri Olsa
2020-09-13 21:02 ` [PATCH 07/26] perf tools: Add check for existing link in buildid dir Jiri Olsa
2020-09-14 5:54 ` Namhyung Kim
2020-09-14 20:18 ` Jiri Olsa
2020-09-13 21:02 ` [PATCH 08/26] perf tools: Use struct extra_kernel_map in machine__process_kernel_mmap_event Jiri Olsa
2020-09-13 21:02 ` [PATCH 09/26] perf tools: Try load vmlinux from buildid database Jiri Olsa
2020-09-14 6:25 ` Namhyung Kim
2020-09-14 20:29 ` Jiri Olsa
2020-09-15 2:58 ` Namhyung Kim
2020-09-13 21:02 ` [PATCH 10/26] perf tools: Enable mmap3 map event when supported Jiri Olsa
2020-09-14 16:05 ` Arnaldo Carvalho de Melo
2020-09-13 21:02 ` [PATCH 11/26] perf tools: Add mmap3 support Jiri Olsa
2020-09-13 21:02 ` [PATCH 12/26] perf tools: Set build id for kernel dso objects Jiri Olsa
2020-09-13 21:03 ` [PATCH 13/26] perf tools: Plug in mmap3 event Jiri Olsa
2020-09-13 21:03 ` [PATCH 14/26] perf tools: Add mmap3 events to --show-mmap-events option Jiri Olsa
2020-09-14 6:30 ` Namhyung Kim
2020-09-14 20:29 ` Jiri Olsa
2020-09-13 21:03 ` [PATCH 15/26] perf tools: Synthesize proc tasks with mmap3 Jiri Olsa
2020-09-14 16:07 ` Arnaldo Carvalho de Melo
2020-09-14 20:51 ` Jiri Olsa
2020-09-13 21:03 ` [PATCH 16/26] perf tools: Synthesize modules " Jiri Olsa
2020-09-14 16:07 ` Arnaldo Carvalho de Melo
2020-09-15 20:17 ` Ian Rogers
2020-09-16 8:20 ` Jiri Olsa
2020-09-16 14:07 ` Arnaldo Carvalho de Melo
2020-09-16 14:17 ` peterz
2020-09-16 15:10 ` Arnaldo Carvalho de Melo
2020-09-16 15:20 ` peterz
2020-09-16 15:21 ` Jiri Olsa
2020-09-16 15:42 ` Arnaldo Carvalho de Melo
2020-09-13 21:03 ` [PATCH 17/26] perf tools: Synthesize kernel " Jiri Olsa
2020-09-14 16:08 ` Arnaldo Carvalho de Melo
2020-09-13 21:03 ` [PATCH 18/26] perf tests: Add mmap3 support for perf record test Jiri Olsa
2020-09-13 21:03 ` [PATCH 19/26] perf tools: Add buildid-list support for mmap3 Jiri Olsa
2020-09-13 21:03 ` [PATCH 20/26] perf tools: Add build_id_cache__add function Jiri Olsa
2020-09-14 16:13 ` Arnaldo Carvalho de Melo
2020-09-13 21:03 ` [PATCH 21/26] perf tools: Add machine__for_each_dso function Jiri Olsa
2020-09-14 16:15 ` Arnaldo Carvalho de Melo
2020-09-13 21:03 ` [PATCH 22/26] perf tools: Use machine__for_each_dso in perf_session__cache_build_ids Jiri Olsa
2020-09-13 21:03 ` [PATCH 23/26] perf tools: Add __perf_session__cache_build_ids function Jiri Olsa
2020-09-13 21:03 ` [PATCH 24/26] perf tools: Add buildid-list --store option Jiri Olsa
2020-09-14 6:42 ` Namhyung Kim
2020-09-14 15:14 ` Arnaldo Carvalho de Melo
2020-09-14 20:42 ` Jiri Olsa
2020-09-14 20:42 ` Jiri Olsa
2020-09-13 21:03 ` [PATCH 25/26] perf tools: Move debuginfo download code into get_debuginfo Jiri Olsa
2020-09-13 21:03 ` [PATCH 26/26] perf tools: Add report --store option Jiri Olsa
2020-09-14 5:25 ` [RFC 00/26] perf: Add mmap3 support Namhyung Kim
2020-09-14 15:13 ` Arnaldo Carvalho de Melo
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