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Re: on the speed of std::string::find


Dennis Lubert wrote:

Hi, I did some simple benchmarks with the different implementation.
yours is the "new find patch" implementation, which seems to be a bit
faster at start, but scales worse. I didn't had enough time today, but I
think within the next few days I can build up a few charts with
descriptions of what I exactly did etc. pp.
http://www.projectiwear.org/~plasmahh/string_bench_simple.png


Dennis, thanks for your help, but something is certainly wrong in the benchmarking, we can't trust it. Likely, it's because of the optimization level, or something else. As I said already, you must use -O2, otherwise we are measuring something which nobody will see in practice. I'm saying that because the "new" implementation is *identical* to glibc' memmem, the difference should be withing a few % (indeed, the timings I'm seeing on many different machines are consistent with those your reported days ago, certainly about 1.5-2.0 x faster than the current implementation). Also, please use many different strings: either use our performance testcase or a bi amount of *real* data.

Please let me know ASAP if you are able to conduct such kind of tests, otherwise we are delaying unnecessarily closing the issue, thanks
Paolo.



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