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How do profilers work?

Started by CloudNine Apr 7, 2005 at 7:10 AM 2 replies 900+ views

Original Post

Apr 7, 2005 at 7:10 AM

Lo, How do code profilers like Intel's VTune profile the code? Do they instrument the code with timers etc. automatically, and if so, how? I know GNU gprof is a good free software profiler, is it a typical example of a profiler? I've always been interested in how they work, and the detail of VTune surprises me. CloudNine

Trap

Apr 7, 2005 at 7:37 AM

There essentially are 2 ways to do profiling:
a) intrusive (place timers in code)
b) statistical (every x cycles check location in code)

Usually statistical profiling is what you want to use because it shows the behaviour of the real code.

Skizz

Apr 7, 2005 at 7:39 AM

You can also do it through simulation, which VTune does as well as the above. By this I mean analysing the code for potential stalls and such like.

Skizz

CloudNine

Apr 7, 2005 at 10:19 AM

Ah, interesting. Is the statistical profiling performed from outside the application, and if so, how is it possible to get the instruction pointer of the task?

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