Date: Thu, 14 Sep 2006 09:40:27 -0400 From: Mike Meyer <mwm-keyword-freebsdhackers2.e313df@mired.org> To: Danny Braniss <danny@cs.huji.ac.il> Cc: freebsd-hackers@freebsd.org, Kris Kennaway <kris@obsecurity.org> Subject: Re: numbers don't lie ... Message-ID: <17673.23499.581046.259914@bhuda.mired.org> In-Reply-To: <E1GNoDy-0004CF-5k@cs1.cs.huji.ac.il> References: <E1GNoDy-0004CF-5k@cs1.cs.huji.ac.il>
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In <E1GNoDy-0004CF-5k@cs1.cs.huji.ac.il>, Danny Braniss <danny@cs.huji.ac.il> typed: > > In <E1GNOLq-000DC2-1Q@cs1.cs.huji.ac.il>, Danny Braniss <danny@cs.huji.ac.il> typed: > > What's the CPU configuration? The AMD is dual core - is that it? Could > > the Xeon be dual-core and hyperthreaded, so it's got that many more > > CPUs to contribute towards user time? > > > > To illustrate, I have numbers for "make -j4" for a P4 with and without > > hyperthreading enabled: > > > > machdep.hyperthreading_allowed: 1 -> 0 > > 50m55.99s real 35m28s.19 user 8m20s.02 sys > > machdep.hyperthreading_allowed: 0 -> 1 > > 38m48s.85 real 55m2s.43 user 12m27s.90 sys > > > > Note the effect of the second CPU on the user time. > > > i did the tests with hyperbluffing disabled in the bios. > now, since you asked i tried: > sysctl machdep.cpu_idle_hlt=0 > machdep.cpu_idle_hlt: 1 -> 0 > dell-2950 : make -j8 TARGET_ARCH=amd64 buildworld : 23m55.03s real 1h2m54.84s > user 16m48.79s sys > and no difference, by the way, i did this also changing the bios setting > (called logical cpus :-), but again, no difference. Um - what version of FreeBSD are you running? I don't change machdep.cpu_idle_hlt on mine; I chang machdep.hyperthreading_allowed (as indicated in the tests). Did you check to see if the system actually saw more cpus when you changed it? <mike -- Mike Meyer <mwm@mired.org> http://www.mired.org/consulting.html Independent Network/Unix/Perforce consultant, email for more information.
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