Re: Speed comparison of regex versus index, lc, and / /i

On Sat, 31 May 2008 07:19:24 +0000, John W. Krahn wrote:

On my machine and version of Perl a get a speed improvement by using a C
style for loop instead:

I think this is just an artifact of using a string which matches
several times.

On my machine and version of Perl regex_unur_find() and
regex_morrow_find() are statically the same;

Rate regex regex_unur regex_morrow index_while
index_for
regex 144442/s -- -5% -6% -16%
-17%
regex_unur 151952/s 5% -- -1% -11%
-13%
regex_morrow 154059/s 7% 1% -- -10%
-12%
index_while 171325/s 19% 13% 11% --
-2%
index_for 174905/s 21% 15% 14% 2%

I repeated the test with Perl 5.8 and got similar results to you.

It seems like the Ben Morrow version has been de-optimized, and the
A. Sinan Unur version optimized, in Perl 5.10.

Perl 5.10:

regex_morrow 138889/s -- -32% -40% -40%
regex 204082/s 47% -- -12% -12%
regex_unur 232558/s 67% 14% -- -0%
index 232558/s 67% 14% 0% --

Perl 5.8:

regex 178571/s -- -7% -7% -21%
regex_unur 192308/s 8% -- -0% -15%
regex_morrow 192308/s 8% 0% -- -15%
index 227273/s 27% 18% 18% --

(repeating the test several times gave both faster and slower times
for unur and morrow versions, with both being roughly the same.)
.

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