Re: [PATCH 3/3] scripts/performance: Add perf_top_25.py script

[Alex Bennée]

Ahmed Karaman <ahmedkhaledkaraman@gmail.com> writes:

> On Wed, Jun 17, 2020 at 2:21 PM Alex Bennée <alex.bennee@linaro.org> wrote:
>
>> > +
>> > +# Run perf repcord and report
>> > +os.system('sudo perf record {} {} 2> /dev/null \
>> > +            && sudo perf report --stdio > tmp.perf.data'
>> > +          .format(qemu_path, executable))
>>
>> Why sudo?
>
> This is the default requirement by perf. You can modify the
> kernel.perf_event_paranoid setting to run without root privileges.

Right - which I do as a developer. It would be rude to sudo things if
you don't need to because then you end up running your potentially
un-trusted application with root privileges.

Could we either probe for the requirement or require an explicit sudo
flag which we can prompt for if it fails?

>
>> Also redirecting just stderr? why?
>
> Perf, as well as Valgrind, print their output on stderr not stdout.

Right so I think a bit of splitting apart and use of subprocess can make
this cleaner and not involve quite so much being done with shell
redirection in one invocation.

>
>> I think you could separate the steps (as well as use the subprocess
>> api).
>
> Noted!
>
>> Again os.unlink()
>
> Noted!


-- 
Alex Bennée