Date: Sat, 4 Oct 2003 16:39:03 +0200 (CEST) From: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz> To: freebsd-hackers@freebsd.org Subject: Hyperthreading slowdown Message-ID: <Pine.LNX.4.58.0310041623250.6065@artax.karlin.mff.cuni.cz>
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Hi I installed FreeBSD 4.9RC1 on P4 3GHz with hyperthreading and I see drastic slowdown when kernel with hyperthreading is booted. For example program compilation took this time: hyperthreading kernel, make -j 1 --- 1:09 hyperthreading kernel, make -j 2 --- 0:42 singlethreading kernel, make -j 1 --- 0:45 singlethreading kernel, make -j 2 --- 0:41 Compilation does very few system calls so when I compile with only one process (-j 1), it should be as fast as with singlethreading kernel. Do you have any idea why is it so slow? Mikulas
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