[Haskell-cafe] Threading and Mullticore Computation

Bulat Ziganshin bulat.ziganshin at gmail.com
Tue Mar 3 13:40:20 EST 2009

Hello Andrew,

Tuesday, March 3, 2009, 9:21:42 PM, you wrote:

> I just tried it with GHC 6.10.1. Two capabilities is still slower. (See
> attachments. Compiled with -O2 -threaded.)

i don't think so:

  Total time    4.88s  (  5.14s elapsed)

  Total time    7.08s  (  4.69s elapsed)

so with 1 thread wall clock time is 5 seconds, with 2 thread wall time
is 4.7 seconds

cpu time spent increased with 2 threads - this indicates that you
either use hyperthreaded/SMT-capable cpu or speed is limited by memory
access operations

so, my conclusion - this benchmark limited by memory latencies so it
cannot be efficiently multithreaded

Best regards,
 Bulat                            mailto:Bulat.Ziganshin at gmail.com

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