Re: Help needed

[William C. <wc...@re...>]

On 4/5/22 05:59, Giri Prasad wrote:
> 1) I installed operf in linux machine, below is the version:
> 
> operf: oprofile 1.3.0 compiled on Feb  2 2020 20:33:34
> 
> 2) I wrote a simple program and ran : *operf ./a.out*
> 
> 3) it generated the folder: *oprofile_data*
> *
> *
> 4) when i run opreport as below:
> *
> *
> *##> opreport session:oprofile_data event:DATA_MEM_REFS
> Using /home/prasadgi/tools/cpp/oprofile_data/samples/ for samples directory.
> opreport error: No sample found: Please specify a session containing
> sample data.*
> *
> *
> *Please help what is missing ?*
> *
> *
> Regards,
> Giri Prasad
> 
> 
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Hi,

By default operf is going to use a clock cycle event to record samples .   You should see samples if you do "opreport".  However, if the program runs for a very short amount of time there might not be enough events (cycles) to trigger a sample.  If you want to get samples of the DATA_MEM_REFS you are going to need to specify the events with the --events / -e option for operf:


https://oprofile.sourceforge.io/doc/controlling-profiler.html#controlling-operf

You might also consider using linux perf:

https://perf.wiki.kernel.org/index.php/Main_Page

-Will