How can I disable hyperthreads, but NOT smp ?
richard at blueapex.co.uk
Tue Sep 20 21:28:21 UTC 2011
On 20/09/2011 21:34, Jason Usher wrote:
> FreeBSD 6.4-RELEASE system with two physical CPUs, each of which are HT capable. From dmesg:
> cpu0 (BSP): APIC ID: 0
> cpu1 (AP): APIC ID: 1
> cpu2 (AP): APIC ID: 6
> cpu3 (AP): APIC ID: 7
> I also see this:
> machdep.hyperthreading_allowed: 0
> The problem is, I have reason to believe that my workload benefits greatly from SMP, but is not playing nicely with hyperthreading. That is, it is trying to farm out 4 things at a time to a cpu setup that really is only able to do two things at a time.
> How can I disable HT completely, but still retain ALL the benefits of SMP ?
It's usually a setting in the BIOS to disable Hyperthreading then
reconfigure the kernel to only use 2 cores (which it might do
Hyperthreading is outside the world of FreeBSD. As far as it knows there
is still 4 "logical processors". Disabling hyperthreading it should see
Blue Apex Ltd
07900 997 380
Registered as a company in England and Wales (Reg Number: 05982514).
Registered Address: 42 King Richards Hill, Earl Shilton, Leicester, LE9 7EY
__________ Information from ESET NOD32 Antivirus, version of virus signature database 6480 (20110920) __________
The message was checked by ESET NOD32 Antivirus.
More information about the freebsd-questions