From: Bulat Ziganshin <[EMAIL PROTECTED]>
Reply-To: Bulat Ziganshin <[EMAIL PROTECTED]>
To: "Branimir Maksimovic" <[EMAIL PROTECTED]>
CC: [EMAIL PROTECTED], 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.
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