linux-kernel - Re: [PATCH v1 0/3] Support perf -vv

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Date:   Mon, 26 Mar 2018 21:06:30 +0800
From:   "Jin, Yao" <yao.jin@...ux.intel.com>
To:     Jiri Olsa <jolsa@...hat.com>, Andi Kleen <ak@...ux.intel.com>
Cc:     acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        Linux-kernel@...r.kernel.org, kan.liang@...el.com,
        yao.jin@...el.com
Subject: Re: [PATCH v1 0/3] Support perf -vv



On 3/26/2018 5:07 PM, Jiri Olsa wrote:
> On Mon, Mar 26, 2018 at 02:00:31AM -0700, Andi Kleen wrote:
>> On Tue, Mar 27, 2018 at 12:07:01AM +0800, Jin Yao wrote:
>>> We keep having bug reports that when users build perf on their own,
>>> but they don't install some needed libraries such as libelf,
>>> libbfd/libibery.
>>>
>>> The perf can build, but it is missing important functionality. And
>>> users may complain that perf has issue or bug.
>>>
>>> This patch-set support 'perf -vv' which will print the compiled-in
>>> status of libraries. Once users think perf missing some functionality,
>>> it should be very easy for them to check the libraries status.
>>
>> I don't think this solves the problem. How should the user know
>> that they need to run perf -vv. Also normal users don't know
>> that libelf is needed for symbols for example.
>>
>> We need a warning that is visible together with the symbols
>> and that clearly describes the problem.
> 
> IIRC we decided to go *with* the message in the perf report
> or other affected command that would suggest to run 'perf -vv'
> for more details
> 
> jirka
> 

Hi Andi,

For how the users know they should run 'perf -vv', as the discussion 
with Jiri and Arnaldo, the message will be displayed if necessary when 
users perform perf report or other perf commands. That could be 
implemented in a follow-up patch (not in this patch-set).

For let user know what the library they need, maybe we can add more 
information in 'perf -vv', for example, add something like,

"Please install libelf-dev, libelf-devel or elfutils-libelf-devel before 
building perf"

Thanks
Jin Yao

>>
>> -Andi
>>
>>>
>>> For example:
>>>
>>> $ ./perf -vv
>>> perf version 4.13.rc5.g9b7a81b
>>>                   dwarf: [  on ]
>>>      dwarf_getlocations: [  on ]
>>>                   glibc: [  on ]
>>>                    gtk2: [  on ]
>>>                libaudit: [ off ]
>>>                  libbfd: [  on ]
>>>                  libelf: [  on ]
>>>                 libnuma: [  on ]
>>> numa_num_possible_cpus: [  on ]
>>>                 libperl: [  on ]
>>>               libpython: [  on ]
>>>                libslang: [  on ]
>>>               libcrypto: [  on ]
>>>               libunwind: [  on ]
>>>      libdw-dwarf-unwind: [  on ]
>>>                    zlib: [  on ]
>>>                    lzma: [  on ]
>>>               get_cpuid: [  on ]
>>>                     bpf: [  on ]
>>>
>>> Jin Yao (3):
>>>    perf config: Add -DNO_GLIBC to CFLAGS
>>>    perf version: Print the status of compiled-in libraries
>>>    perf: Support perf -vv
>>>
>>>   tools/perf/Makefile.config   |   2 +
>>>   tools/perf/builtin-version.c | 125 +++++++++++++++++++++++++++++++++++++++++++
>>>   tools/perf/builtin.h         |   1 +
>>>   tools/perf/perf.c            |   6 +++
>>>   4 files changed, 134 insertions(+)
>>>
>>> -- 
>>> 2.7.4
>>>