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kaul84 / likwid

Automatically exported from code.google.com/p/likwid
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collecting pmu values at regular interval #140

Open GoogleCodeExporter opened 9 years ago

GoogleCodeExporter commented 9 years ago 
What steps will reproduce the problem?
1. Is it possible to collect the event stats at a regular interval of 10 
million instructions or so? I don't see the timeline function working properly 
for multithreaded program using perfcntr.
2.
3.

What is the expected output? What do you see instead?
Is it possible to make modifications in existing likwid-perfcntr?

What version of the product are you using?

Please provide any additional information below.

Original issue reported on code.google.com by sur...@gmail.com on 11 Mar 2014 at 1:31

GoogleCodeExporter commented 9 years ago 
Please provide more details on why timeline mode does not work for threaded 
case.

Original comment by jan.trei...@gmail.com on 8 May 2014 at 12:37

GoogleCodeExporter commented 9 years ago 
Since no additional information was postet by 'sursri' we cannot work on the 
problem with the multithreaded timeline measurements.

For your first question. Yes it is possible, but there is currently no 
implementation of this behavior. The steps are the following:
- Initialize counter as normal but enable interrupt on overflow (polling would 
also be possible but does not provide accurate results)
- Set desired counter register (  Something like PMC0 with event 
INSTRUCTIONS_RETIRED to 2^(register width) - (instruction interval)  )
- Start counters
- On interrupt read all configured counters and reinitialize counter registers.
And so on.

Original comment by Thomas.R...@googlemail.com on 5 Aug 2014 at 11:59

GoogleCodeExporter commented 9 years ago 
Not implemented in Likwid 4.0

Likwid does not use the interrupts, so only polling possible.

Original comment by Thomas.R...@googlemail.com on 5 May 2015 at 9:00