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 ?
Thanks.
It's usually a setting in the BIOS to disable Hyperthreading then
reconfigure the kernel to only use 2 cores (which it might do
automatically).
Hyperthreading is outside the world of FreeBSD. As far as it knows there
is still 4 "logical processors". Disabling hyperthreading it should see
2 LPs.
Richard
--
Richard Collyer
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
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