RE:(2) Algorithm Efficiency (function overhead)

aighearach, I saw the same thing, but forgot to post anything about it. Thank you.

I wonder about this as well. I suspected it was the profiler causing the extra overhead, but your results show it happening with just Benchmark. I have run it this way myself and found similar results.

This is funny. I "preach" to co-workers to forget their 'C' days, and ignore performance. "Perl is about programmer efficiency, not CPU efficiency," I say. Now, I am fascinated with this discussion, which is all about esoteric trivia of Perl efficiency.

:-)

Russ

Comment on RE:(2) Algorithm Efficiency (function overhead)

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RE: RE:(2) Algorithm Efficiency (function overhead) by btrott (Parson) on Jun 21, 2000 at 00:53 UTC
No, it's not the extra weight of the subroutine calls, although sub calls do cause more overhead. What's causing this is what I mentioned earlier: you have scoping problems. None of the code you're benchmarking is actually using a valid value for either %url or $now. So your results are completely bogus. The valid results are those that use a properly scoped variable. Aighearach's code did this, though I'm not sure it did so intentionally. You can accomplish this by declaring your vars as package globals: `use vars qw/$now %url/; $now = 8; %url = ( monday => { @{[map(($_,1), (1..1000))]} } );` [download] This gives valid results. `Benchmark: timing 1000 iterations of Grep, Max, Ternary... Grep: 6 wallclock secs ( 5.49 usr + 0.00 sys = 5.49 CPU) Max: 5 wallclock secs ( 5.81 usr + 0.00 sys = 5.81 CPU) Ternary: 7 wallclock secs ( 6.42 usr + 0.00 sys = 6.42 CPU)` [download]	[reply] [d/l] [select]

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RE: RE:(2) Algorithm Efficiency (function overhead)
by btrott (Parson) on Jun 21, 2000 at 00:53 UTC

The valid results are those that use a properly scoped variable. Aighearach's code did this, though I'm not sure it did so intentionally.

You can accomplish this by declaring your vars as package globals:

    use vars qw/$now %url/;

    $now = 8;
    %url = ( monday => { @{[map(($_,1), (1..1000))]} } );
[download]

Benchmark: timing 1000 iterations of Grep, Max, Ternary...
      Grep:  6 wallclock secs ( 5.49 usr +  0.00 sys =  5.49 CPU)
       Max:  5 wallclock secs ( 5.81 usr +  0.00 sys =  5.81 CPU)
   Ternary:  7 wallclock secs ( 6.42 usr +  0.00 sys =  6.42 CPU)
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