4.8 hyperthreading changes

[Aristedes Maniatis]

 From the 4.8 changes page I found this:

> FreeBSD now has rudimentary support for HyperThreading (HTT). SMP 
> kernels with the HTT  kernel option will detect and start up the 
> logical processors on HTT-capable machines. The logical processors 
> will be treated like additional physical processors for the purposes 
> of process scheduling.

On the 4.7 deployment systems I am running I have dual Xeon CPUs with 
hyperthreading. They appear as 4 CPUs in 'top'. That would seems to 
indicate to me that FreeBSD is scheduling them as four separate 
processors, however the note from:

http://www.freebsd.org/relnotes/4-STABLE/relnotes/i386/x19.html#KERNEL

makes it seem like this is a new 4.8 feature. Should I be concerned 
about upgrading when 4.8 is released in order to obtain the benefits of 
better use of these CPUs?


Ari Maniatis

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