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Subject: Re: [boost] [xpressive] Performance Tuning?
From: Paul Baxter (pauljbaxter_at_[hidden])
Date: 2009-07-28 15:52:05

I'm really appreciative of the testing you are all doing with parsing code
and hope that at the end we can see both how fast and how clear and
maintainable the various styles of parser code become (focus on accuracy,
speed then perhaps more on the clarity).

Its great to see the enthusiasm and results. Looking forward to more tips
once we have a fair test directly pitting spirit with expressive and other
parsing methodologies.

I also am encouraged by what Edward's timer might add though I'm a little
wary of possible inclusion of code following FFTW's license as it may be
incompatible with Boost.

Edward, I do wonder about the statistical significance metrics you provide
(great idea by the way).
I'm wondering if your code assumes a normal timing duration distribution and
if so, can it 'measure' whether the distribution of results conform to this

In my experience, timing benchmarks can suffer from having outliers (usually
OS-induced by not having a RTOS) that make the distribution less than

Would it be possible to establish that the given sample set of timings
correspond to a normal distribution (or perhaps discard a certain percentage
of outliers if necessary). I'm no statistics person, but I have seen cases
where 10,000 timing samples have been biased by 10 samples that probably
relate to a program issue or a severe OS issue. e.g. normally 1 ms per
iteration, 10 @ 1-10s each

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