Re: [GIT PULL 0/6] perf/core improvements and fixes

["Wangnan (F)" <wangnan0@huawei.com>]

On 2015/6/4 13:48, Ingo Molnar wrote:
> * Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
>
>> Hi Ingo,
>>
>> 	Please consider applying.
>>
>> 	One of the next requests probably will have the eBPF work by Wang Nan,
>> but I am still going thru it and want to test it thoroughly.
>>
>> 	BTW: Have you looked at it lately? It is at:
>>
>> http://lkml.kernel.org/r/1433144296-74992-1-git-send-email-wangnan0@huawei.com
>>
>> Super summary from the above cover letter:
>>
>> ---------------------
>> It enables 'perf record' to filter events using eBPF programs like:
>>
>>   # perf record --event bpf-file.o sleep 1
>>
>> Events are selected and filtered according to definitions in bpf-file.o.
> Looks useful, but I think the UI needs one more tweak: could you fix it to be able
> to filter based on the eBPF _source_ file, not just the object file?
>
> People want to tweak such filters as they profile, so we should use the eBPF
> source code as the primary interface. We can compile it internally to the .o just
> fine. The .o file is a totally uninteresting intermediate product in itself.
>
> I.e. we need to first think through such profiling workflows from beginning to end
> before allowing them upstream.

In a private mail Alexei Starovoitov disscussed with me about this. He 
said that he is working
on a shared object which can compile C program into BPF bytecode on the 
fly. After he done his
work, I think perf can support dtrace-like profiling that, users will be 
able to feed source
code to perf directly on cmdline. He said he can release it on June. I 
added him to the CC-list.

However I think the '.o' intermediate is still needed. I'd like to share 
a real profiling
experience using eBPF today, please keep an eye on it. In my experience, 
since we are using C
instead of dtrace, the code piece could be relative complex. Therefore, 
even if perf is able
to compile the C source on the fly, I think user still need to transfer 
the profiling scripts
to the target machine. Therefor, for him, precompiling and do some 
debugging on a high-end server
then transfer it into target machine (like a smartphone) is tolerable, 
and useful for me.

Thank you.

>> ---------------------
>>
>> 	The first two patches from that series are in this pull req, as
>> they just move stuff into tools/include/linux/ from tools/perf/include.
>>
>> Regards,
>>
>> - Arnaldo
>>
>> The following changes since commit 5c9b9bc67c684e40b3a5e7e9facde0fb7200cd8c:
>>
>>    Merge tag 'perf-core-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core (2015-05-29 20:19:02 +0200)
>>
>> are available in the git repository at:
>>
>>    git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git tags/perf-core-for-mingo
>>
>> for you to fetch changes up to 1f121b03d058dd07199d8924373d3c52a207f63b:
>>
>>    perf tools: Deal with kernel module names in '[]' correctly (2015-06-03 10:02:38 -0300)
>>
>> ----------------------------------------------------------------
>> perf/core improvements and fixes:
>>
>> User visible:
>>
>> - Fix 'perf probe' segfault when glob matching function without debuginfo (Wang Nan)
>>
>> - Remove newline char when reading event scale and unit (Madhavan Srinivasan)
>>
>> - Deal with kernel module names in '[]' correctly (Wang Nan)
>>
>> Infrastructure:
>>
>> - Fix the search for the kernel DSO on the unified list (Arnaldo Carvalho de Melo)
>>
>> - Move tools/perf/util/include/linux/{kernel.h,list.h,poison.h} to tools/include,
>>    to be used in tools/lib/bpf/ (Wang Nan)
>>
>> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
>>
>> ----------------------------------------------------------------
>> Arnaldo Carvalho de Melo (1):
>>        perf machine: Fix the search for the kernel DSO on the unified list
>>
>> Madhavan Srinivasan (1):
>>        perf tools: Remove newline char when reading event scale and unit
>>
>> Wang Nan (4):
>>        perf probe: Fix segfault when glob matching function without debuginfo
>>        perf tools: Move linux/kernel.h to tools/include
>>        tools: Move tools/perf/util/include/linux/{list.h,poison.h} to tools/include
>>        perf tools: Deal with kernel module names in '[]' correctly
>>
>>   tools/{perf/util => }/include/linux/kernel.h |  4 +-
>>   tools/{perf/util => }/include/linux/list.h   |  6 +--
>>   tools/include/linux/poison.h                 |  1 +
>>   tools/perf/MANIFEST                          |  3 ++
>>   tools/perf/tests/kmod-path.c                 | 72 ++++++++++++++++++++++++++++
>>   tools/perf/util/dso.c                        | 47 ++++++++++++++++--
>>   tools/perf/util/dso.h                        |  2 +-
>>   tools/perf/util/header.c                     |  8 ++--
>>   tools/perf/util/include/linux/poison.h       |  1 -
>>   tools/perf/util/machine.c                    | 22 ++++++++-
>>   tools/perf/util/pmu.c                        | 11 ++++-
>>   tools/perf/util/probe-event.c                | 26 ++++++++--
>>   12 files changed, 179 insertions(+), 24 deletions(-)
>>   rename tools/{perf/util => }/include/linux/kernel.h (97%)
>>   rename tools/{perf/util => }/include/linux/list.h (90%)
>>   create mode 100644 tools/include/linux/poison.h
>>   delete mode 100644 tools/perf/util/include/linux/poison.h
> Pulled, thanks a lot Arnaldo!
>
> 	Ingo