RE: Re[2]: [Haskell-cafe] Substring replacements

From: Bulat Ziganshin Reply-To: Bulat Ziganshin To: "Branimir Maksimovic" CC: daniel.is.fischer@web.de, Haskell-Cafe@haskell.org Subject: Re[2]: [Haskell-cafe] Substring replacements Date: Fri, 16 Dec 2005 16:51:32 +0300

Hello Branimir,

Friday, December 16, 2005, 5:36:47 AM, you wrote: BM> I've also performed tests on dual Xeon linux box and results are

just to let you know - GHC don't uses pentium4 hyperthreading, multiple cpus or multiple cores in these tests Oh yes it does. I clearly see multiple threads that take unequal percentage on each virtual CPU. I guess that other thread is garbage collector

thread. In case of hyperthreading, speed is gained by reduced memory latency by 30-60 %

only way to make ghc using multiple processors is to use 6.5 beta version, compile with "-smp" and explicitly fork several threads

This is not the case as I see. On windows search replace test programs spawn 3 threads and on linux I'm not sure, but I've checked program that calls Haskell from C++ and GHC spawns additional thread, which is not my thread, that also performs something constantly, and I didn't spawn any thread from Haskell. So hyperthreading helps as it helps to optimise when several threads accesses memory as is in this test case. I can't see any other explanation why KMP search is slower on AMD 20% , but faster on Intel 30%, then straightforward search with my test. Greetings, Bane. _________________________________________________________________ Express yourself instantly with MSN Messenger! Download today it's FREE! http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/