Re: [Haskell-cafe] Haskell Speed Myth

Recently I wrote computation intensive program that could easily utilize both cores. However, there was overhead just from compiling with -threaded and making some forkIO's. Still, the overhead was not larger than 50% and with 4 cores I would probably still get the results faster - I didn't experience an order of magnitude slowdown. Perhaps it's the issue with OS X. On Sat, Aug 23, 2008 at 21:19, Thomas Davie wrote:

On 23 Aug 2008, at 20:01, Luke Palmer wrote:

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2008/8/23 Thomas Davie :

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Finally, that threading example... WOW! 65 times faster, and the code is *really* simple. The C on the other hand is a massive mess.

I've been wondering about this, but I can't check because I don't have a multi core cpu. I've heard GHC's single threaded runtime is very very good. What are the results for the threading example when compiled with -threaded and run with at least +RTS -N2?

That's really interesting -- I just tried this.

Compiling not using -threaded: 1.289 seconds Compiling using -threaded, but not running with -N2: 3.403 seconds Compiling using -threaded, and using -N2: 55.072 seconds

Wow! Haskell's runtime really is a *lot* better than trying to use operating system threads. I wonder if there's a point at which it becomes better to use both CPUs, or if the overhead of using OS threads for that problem is just too high.

Bob _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe