From: Song Liu <songliubraving@fb.com>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>,
Stephane Eranian <eranian@google.com>,
Netdev <netdev@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
"daniel@iogearbox.net" <daniel@iogearbox.net>,
Kernel Team <Kernel-team@fb.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"namhyung@kernel.org" <namhyung@kernel.org>
Subject: Re: [PATCH v2 perf,bpf 08/11] perf, bpf: save btf information as headers to perf.data
Date: Fri, 15 Feb 2019 18:59:14 +0000 [thread overview]
Message-ID: <F6877640-F6A6-4F2D-B756-0092D7B1237F@fb.com> (raw)
In-Reply-To: <20190215182047.GL31177@kernel.org>
> On Feb 15, 2019, at 10:20 AM, Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
>
> Em Fri, Feb 15, 2019 at 05:47:58PM +0000, Song Liu escreveu:
>>
>>
>>> On Feb 15, 2019, at 9:40 AM, Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
>>>
>>> Em Fri, Feb 15, 2019 at 05:25:01PM +0000, Song Liu escreveu:
>>>>> On Feb 15, 2019, at 6:26 AM, Arnaldo Carvalho de Melo <acme@redhat.com> wrote:
>>>>> Em Thu, Feb 14, 2019 at 04:00:09PM -0800, Song Liu escreveu:
>>>>>> This patch enables perf-record to save btf information as headers to
>>>>>> perf.data A new header type HEADER_BTF is introduced for this data.
>>>
>>>>> Wouldn't it be better for this HEADER_BTF to be introduced
>>>>> already as an user space event, Song, see:
>>>
>>>>> tools/perf/util/event.h
>>>
>>>>> and:
>>>
>>>>> tools/perf/util/event.c
>>>
>>>>> perf_event__synthesize_cpu_map()
>>>
>>>> BTF would be short living for short living BPF programs. I guess
>>>> saving them as header is easier than merging them with samples.
>>>
>>>> What's the benefit of saving them as user space events?
>>>
>>> When we work with pipe mode, i.e.:
>>>
>>> perf record -o - | perf report -i -
>>>
>>> and other combinations (with 'perf script', 'perf inject', etc), we need
>>> a way to pass the headers to the other side, and the way was via user
>>> space events.
>>>
>>> This is something Stephane and Jiri have been discussing recently,
>>> probably they have more justifications, Stephane, Jiri?
>>>
>>> - Arnaldo
>>
>> I see. In this case, we will need some synchronization between main
>> thread and the polling thread, as they are both writing to the same
>> pipe.
>
> So, the whole context is that we need to have 'perf record' to start a
> thread per CPU and then read the already per-cpu mmap buffers in the
> matching thread, with the right affinity, numa settings to have the
> record phase not cause contention, etc, so it ends up dumping one stream
> per CPU in a separate file in a 'perf.data' directory instead of a
> perf.data file.
>
> Jiri is working on that, so, if you dump one more stream into that
> directory, it would, at post processing time, be ordered together with
> the other stream, the per-cpu ones.
>
> - Arnaldo
I see. This solution looks great.
For this set, how about I keep this part as-is (at least for v3)? In
this case, it will goes to the header file after Jiri's change. Once
Jiri's work is done, I will move them into per-cpu files.
Thanks,
Song
next prev parent reply other threads:[~2019-02-15 18:59 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-14 23:56 [PATCH v2 perf,bpf 00/11] perf annotation of BPF programs Song Liu
2019-02-14 23:58 ` [PATCH v2 perf,bpf 01/11] perf, bpf: consider events with attr.bpf_event as side-band events Song Liu
2019-02-15 14:14 ` Arnaldo Carvalho de Melo
2019-02-15 17:02 ` Song Liu
2019-02-15 18:04 ` Arnaldo Carvalho de Melo
2019-02-15 0:00 ` [PATCH v2 perf,bpf 02/11] bpf: libbpf: introduce bpf_program__get_prog_info_linear() Song Liu
2019-02-15 0:00 ` [PATCH v2 perf,bpf 03/11] bpf: bpftool: use bpf_program__get_prog_info_linear() in prog.c:do_dump() Song Liu
2019-02-15 0:00 ` [PATCH v2 perf,bpf 04/11] perf, bpf: synthesize bpf events with bpf_program__get_prog_info_linear() Song Liu
2019-02-15 0:00 ` [PATCH v2 perf,bpf 05/11] perf, bpf: save bpf_prog_info in a rbtree in perf_env Song Liu
2019-02-15 14:21 ` Arnaldo Carvalho de Melo
2019-02-15 17:04 ` Song Liu
2019-02-15 0:00 ` [PATCH v2 perf,bpf 06/11] perf, bpf: save bpf_prog_info information as headers to perf.data Song Liu
2019-02-15 0:00 ` [PATCH v2 perf,bpf 07/11] perf, bpf: save btf in a rbtree in perf_env Song Liu
2019-02-15 14:30 ` Arnaldo Carvalho de Melo
2019-02-15 0:00 ` [PATCH v2 perf,bpf 08/11] perf, bpf: save btf information as headers to perf.data Song Liu
2019-02-15 14:26 ` Arnaldo Carvalho de Melo
2019-02-15 17:25 ` Song Liu
2019-02-15 17:40 ` Arnaldo Carvalho de Melo
2019-02-15 17:47 ` Song Liu
2019-02-15 18:20 ` Arnaldo Carvalho de Melo
2019-02-15 18:59 ` Song Liu [this message]
2019-02-15 0:00 ` [PATCH v2 perf,bpf 09/11] perf-top: add option --bpf-event Song Liu
2019-02-15 14:27 ` Arnaldo Carvalho de Melo
2019-02-15 17:06 ` Song Liu
2019-02-15 18:05 ` Arnaldo Carvalho de Melo
2019-02-15 0:00 ` [PATCH v2 perf,bpf 10/11] perf, bpf: enable annotation of bpf program Song Liu
2019-02-15 0:00 ` [PATCH v2 perf,bpf 11/11] perf, bpf: save information about short living bpf programs Song Liu
2019-02-15 14:41 ` Arnaldo Carvalho de Melo
2019-02-15 17:13 ` Song Liu
2019-02-15 18:09 ` Arnaldo Carvalho de Melo
2019-02-15 18:13 ` Song Liu
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