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Re: Differential profiling

by BrowserUk (Pope)
on Jun 26, 2013 at 16:28 UTC ( #1040816=note: print w/ replies, xml ) Need Help??


in reply to Differential profiling

At the moment I am trying to find the best settings for such parameters by doing multiple test runs with the profiler enabled, but with different settings for the parameters, and then comparing the html reports visually

Be aware that the vary act of profiling can significantly change the relative performance of different parts of your code in addition to an across the board slowdown.

Profilers have a habit of adding a fixed overhead to every instrumented point which means they have a disproportionate affect in tight, fast loops and small subroutines and methods.

It's often good to sanity check what you're doing by logging a few hires timestamps at critical junctures: each iteration of an outer loop; or the start and end of each major phase of the program. It's easy to spend your time chasing the dragon of pretty graphs only to find you've expended undue energies on insignificant parts of your program because of the disproportionate affects of the profiling probes.


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Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
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