Re: [cmake-developers] Profile Cmake scripts

[Alexander Neundorf]

On Sunday, December 27, 2015 18:40:27 Dimitar Yordanov wrote:
> Hi all,
> 
> I was searching for a way to profile CMake scripts in order to find
> bottlenecks and possibilities to improve performance. I found out that
> someone already invested time on that [1] providing a minimal 
solution. The
> idea behind it is to use the cmake "--trace" option and to output a time
> stamp and a stack depth with each executed command. The trace log 
is
> afterwards used by a Python script, which transforms it into a more
> readable format.

I actually simply used valgrind/callgrind and got useful results from that.
Usually you see mostly string handling related functions.

Alex

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[cmake-developers] Profile Cmake scripts

[Dimitar Yordanov]

Hi all,

I was searching for a way to profile CMake scripts in order to find
bottlenecks and possibilities to improve performance. I found out that
someone already invested time on that [1] providing a minimal solution. The
idea behind it is to use the cmake "--trace" option and to output a time
stamp and a stack depth with each executed command. The trace log is
afterwards used by a Python script, which transforms it into a more
readable format.

In [1] there existed already a patch for CMake 2.8. This can be easily
adapted for CMake 3.4. One of the issues with that approach is that the
add_subdirectory() command creates a new stack and thus starts the depth
count back from one again. I think it would be more appropriate to work
around that in the Python script, which does the processing. A time stamp
at the end of the whole execution would also be needed in order to
calculate the time needed for the last command.

Alternatively, the trace could output a time stamp at the beginning and at
the end of each command. But that would produce larger traces.

So, I would like to ask you for your opinion and if there is willingness to
integrate such a patch in CMake.

For the Python script itself I thought that it would maybe make sense to
create an output in the Callgrind format. No idea if it is possible
though.

1 - https://github.com/volo-zyko/cmake-profile-stats

Regards,
Dimitar
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Re: [cmake-developers] Profile Cmake scripts

[Dimitar Yordanov]

2015-12-27 21:05 GMT+01:00 Alexander Neundorf :
>
> On Sunday, December 27, 2015 18:40:27 Dimitar Yordanov wrote:
>
> > Hi all,
>
> >
>
> > I was searching for a way to profile CMake scripts in order to find
>
> > bottlenecks and possibilities to improve performance. I found out that
>
> > someone already invested time on that [1] providing a minimal solution. The
>
> > idea behind it is to use the cmake "--trace" option and to output a time
>
> > stamp and a stack depth with each executed command. The trace log is
>
> > afterwards used by a Python script, which transforms it into a more
>
> > readable format.
>
>
>
> I actually simply used valgrind/callgrind and got useful results from that.

I agree with you. Running valgrind directly on the cmake binary
provides useful information: I can see which internal cmake functions
are used the most and consume most of the time.

Nevertheless, I think it would be useful to have a higher level
overview. E.g. to see if there are some issues with the scripts
themselves that I use in my project ...

> Usually you see mostly string handling related functions.

malloc and free are on the top of what I see for a random project used
mostly by std::string. Maybe we can optimize something here too?

Regards,
Dimitar
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