Date: Thu, 5 Jan 2006 18:34:52 +0100 From: Walter Hop <freebsd@walter.transip.nl> To: freebsd-questions@freebsd.org Subject: Kernel forces machdep.hlt_cpus, how to change? Message-ID: <60578543.20060105183452@lifeforms.nl>
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Hello all, I'm testing out FreeBSD 6.0R on a Dual Xeon. I want to do some benchmarking of hyperthreading before I put this machine into use, so I am trying to turn off the HLTing of logical cpu's. A stock "SMP" kernel without any options gives the following sysctl's on this machine: machdep.hlt_cpus: 10 machdep.hlt_logical_cpus: 0 machdep.logical_cpus_mask: 10 So even though I have hlt_logical_cpus at 0, the kernel seems to have decided to HLT my cpu's 8 and 2, the 'logical' threads on each Xeon I assume. I've tried to get around this by setting the following: test# cat /boot/loader.conf machdep.hlt_cpus=0 machdep.hlt_logical_cpus=0 But still after booting I get the same result with the cpu's HLTed. I'm not sure if using them for user processes actually helps, but I'd like to experiment with the setting. Any ideas how I should accomplish this? Cheers! Walter Hop Transip BV -- Transip BV | http://www.transip.nl/ Hoogwaardige Innovatie | Aangename Zekerheid
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