Re: [Haskell-cafe] haskell version of fractal benchmark

dons:

sic:

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* Andrew Coppin [070608 02:45]:

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Bayley, Alistair wrote:

[[1]mailto:haskell-cafe-bounces@haskell.org] On Behalf Of Andrew Coppin

Donald Bruce Stewart wrote:

Some things to remember using Doubles:

* {-# OPTIONS -fexcess-precision #-} * -fvia-C * -fbang-patterns * -optc-O2 -optc-mfpmath=sse -optc-msse2 * -optc-march=pentium4

1. What do all those things do? 2. Is the effect actually that large?

Large? Depends what you mean by large, but adding a few flags to get just a 10-20% speedup isn't to be ignored:

Sure - if it really is 10-20%. (And not, say, 0.001 - 0.002%.)

A single data point for all of this, I have a program that calculates:

P^1_i = S_i/sum_k S_k P^m_i = sum_{k!=i} P^1_k*P^m-1_i(S_~k)

Here's timings for the different options:

options run time compile time none 46.401 3.136 -O 5.033 4.906 -O2 4.967 6.755 -O2 -fexcess-precision 3.710 6.396 all listed options 3.602 6.344

My apologies. Misread that last line. /me drinks more tea. -- Don