[Haskell-cafe] Re: Odd parallel haskell observations (some more numbers)

Hi.

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On Mon, 9 Aug 2010 09:44:00 +0200 "JG" == Jean-Marie Gaillourdet wrote: JG> JG> I am no expert in web server tuning, but I will share my thoughts JG> about your approach and expectations nevertheless.

I would better think about ghc than about web server. I believe, that numbers I already provided (especially their deviation) illustrate that sometimes ghc runtime perform quite bad. I also found out that it can do better than it does by default, I can accept that runtime might be not capable to adjust itself to any taks the best way, but then it will be nice to know, for instance, why for such I/O that GC settings change performance in times. To illustrate even more that httpd has nothing to do with the phenomenon I wrote a small C application which does pretty much the same. Numbers tells that apache can serve much faster that it was required to please haskell version (I will remind that it was 3.4 for single-threaded haskell and went as low as 1.9s for 4-threaded). I attached the code just in case. 10:27 sacha@loft4633:~/work/cube-server/tests 99> for i in 1 2 3 4; do for j in `seq 1 5`;do ./getc $i 10000;done;done 1 1.352978 1 1.348888 1 1.344545 1 1.345116 1 1.189060 2 0.668219 2 0.625113 2 0.698073 2 0.732621 2 0.722310 3 0.569121 3 0.581570 3 0.563512 3 0.566186 3 0.564232 4 0.510132 4 0.496181 4 0.529212 4 0.504506 4 0.511847