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 <[EMAIL PROTECTED]> wrote: > > On 23 Aug 2008, at 20:01, Luke Palmer wrote: > >> 2008/8/23 Thomas Davie <[EMAIL PROTECTED]>: >>> >>> 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 > [email protected] > http://www.haskell.org/mailman/listinfo/haskell-cafe > _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
