Re: [PATCH] perf util: Display warning when perf report/annotate is missing some libs

Jin, Yao
2018-03-23T03:09:07Z

On 3/22/2018 4:51 PM, Jiri Olsa wrote:
> On Thu, Mar 22, 2018 at 09:04:10AM +0800, Jin, Yao wrote:
>>
>>
>> On 3/21/2018 11:38 PM, Jiri Olsa wrote:
>>> On Wed, Mar 21, 2018 at 10:11:10AM +0800, Jin, Yao wrote:
>>>> Hi Jiri,
>>>>
>>>> I'm still thinking it's worth displaying the warning when perf missing some
>>>> libraries.
>>>>
>>>> Somebody just told me that perf didn't work well. While after some
>>>> investigations, I found it's just missing some libraries when building the
>>>> perf.
>>>>
>>>> But I have spent some time on getting the root cause. If with this patch, it
>>>> should be very easily to know that.
>>>
>>> true.. Arnaldo, any feedback on this one?
>>>
>>>>> I just think it'd better provide some hints to user. For example,
>>>>> "symbol is disabled and you need to install libelf/xxx", say something
>>>>> like that.
>>>>>
>>>>> But it looks the column can't contain too much information (i.e. no more
>>>>> space to contain the entire hints).
>>>>>
>>>>> Any idea? Or just add this warning in verbose mode?
>>>>>
>>>>>> also your change does not affect tui mode
>>>>>>
>>>>>> annotation for some reason does not start at all.. could be
>>>>>> little more verbose ;-)
>>>>>>
>>>>>> jirka
>>>>>>
>>>>>
>>>>> Yes, it doesn't affect tui mode.
>>>>>
>>>>> Or we just add this warning in verbose mode?
>>>>>
>>>>> e.g. perf report -v?
>>>
>>> how about displaying libraries separately with -vv output,
>>> that would mimic the build message, like:
>>>
>>> $ ./perf -vv
>>> perf version 4.16.rc6.g18fd48
>>>
>>> dwarf: [ on ]
>>> dwarf_getlocations: [ on ]
>>> glibc: [ on ]
>>> gtk2: [ on ]
>>> libaudit: [ on ]
>>> 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 ]
>>>
>>> and perf -vvv could display the 'make VF=1' info
>>>
>>> jirka
>>>
>>
>> I'm just afraid that the newbie will not check the -vv on his own when he
>> gets trouble in using perf.
>>
>> In other words, if a user is experienced and he knows -vv yet, I may assume
>> that he should know installing all libraries before building the perf.
>>
>> This patch is specific for the perf newbie. It will directly shows the
>> error/warning when the user launches the perf binary. It will have a little
>> bit helps, I guess. :)
>
> I just don't like the idea that when you run perf report,
> or annotate it spits out lines for every missing feature
>
> maybe we could detect missing features for given command
> and display line about missing features and say something
> like:
>
> 'Warning: symbol,dwarf support not compiled in (for more details run perf -vv)'
>
> or somwthing like that.. ;-)
>
> jirka
>

Hi Jiri,

I think your idea is very good!

I guess following it's just an example copied from perf building
process, right?

$ ./perf -vv
perf version 4.16.rc6.g18fd48

dwarf: [ on ]
dwarf_getlocations: [ on ]
glibc: [ on ]
gtk2: [ on ]
libaudit: [ on ]
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 ]

We can check some CFLAGS like "#ifdef HAVE_XXX" in perf code to
determine if some libraries are compiled in.

For example,

#ifdef HAVE_LIBNUMA_SUPPORT
printf("libnuma: [ on ]");
#endif

For some features, such as "numa_num_possible_cpus", which doesn't have
CFLAGS variables. Maybe we can ignore them in report?

I'd like to upgrade my patch to support perf -vv.

Thanks
Jin Yao