Date: Thu, 04 May 2006 17:54:24 -0400 From: "Jonathan Noack" <noackjr@alumni.rice.edu> To: "Marc G. Fournier" <scrappy@hub.org> Cc: freebsd-stable@freebsd.org Subject: Re: Hyperthreading in 6.x ... still frowned upon? Message-ID: <445A7810.5010702@alumni.rice.edu> In-Reply-To: <20060503113955.U1147@ganymede.hub.org> References: <20060503113955.U1147@ganymede.hub.org>
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Marc G. Fournier wrote: > In 4.x, it was a 'shut it off' sort of deal .. my new amd64 don't appear > to have it enabled, but my older i386 server that I just upgraded to 6.x > does: > > user pid %cpu %mem vsz rss tt state start time command > root 14 104.0 0.0 0 8 ?? RL 11:38AM 0:55.02 [idle: > cpu0] > root 11 99.1 0.0 0 8 ?? RL 11:38AM 0:00.00 [idle: > cpu3] > root 13 99.1 0.0 0 8 ?? RL 11:38AM 0:00.00 [idle: > cpu1] > root 12 98.0 0.0 0 8 ?? RL 11:38AM 0:54.54 [idle: > cpu2] > > Is it still something that I should disable, and, if so, how in 6.x? According to the 6.0 i386 Release Notes, you should use the machdep.hyperthreading_allowed sysctl to disable Hyper-Threading. If you are concerned with security, you should disable it. If you are more concerned with performance, you should test your workload with/without Hyper-Threading and choose the configuration which performs best. -Jonathan
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