Re: Clocking Portion of Your Perl Code

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Re^2: Clocking Portion of Your Perl Code by salva (Canon) on Jun 12, 2005 at 12:00 UTC
just a warning about the use of profiling modules to time things: perl profilers work running additional perl code between every instruction and subroutine call. That introduces overhead and affects performance and timing, sometimes in a no linear fashion. What looks faster under a profiler will actually run slower in normal execution. So, profilers are good to find hot spoots in code but not to compare different algorithms or implementations.	[reply]
Re^3: Clocking Portion of Your Perl Code by Anonymous Monk on Jun 12, 2005 at 16:02 UTC
That introduces overhead and affects performance and timing Dear salva, Thanks so much for your important comment! Does that also affect timing with Benchmark or Benchmark::Timer? If so what's the best way to time the portion of your code without having have to add overhead.	[reply]
Re^4: Clocking Portion of Your Perl Code by salva (Canon) on Jun 12, 2005 at 18:47 UTC
You can usually trust Benchmark (I don't know about Benchmark::Timer)... but it's not perfect either: Benchmark.pm: Does subroutine testing order bias results? Sometimes, timing the full program (or a script specially written for the ocasion) from the shell with `time` is also a good solution.	[reply] [d/l]
Re^2: Clocking Portion of Your Perl Code by Anonymous Monk on Jun 12, 2005 at 03:32 UTC
In Benchmark module, I also mean that with 'timethese' etc method. I do have to _separate out_ the code that I want to measure the time. This is inconvenient. Is it possible to time those part without altering the overall structure of my code? Devel::Profiler only time the code as a whole not portion of it.	[reply]
Re^2: Clocking Portion of Your Perl Code by Anonymous Monk on Jun 12, 2005 at 03:22 UTC
I thought Benchmark is only used for "comparing" subroutines, etc. I don't recall any method in Benchmark that does stand-alone time measurement.	[reply]
Re^3: Clocking Portion of Your Perl Code by monkfan (Curate) on Jun 12, 2005 at 03:26 UTC
Check these methods in Benchmark: `timethis timeit countit` [download] Regards, Edward	[reply] [d/l]