cvs commit: src/sys/amd64/amd64 mp_machdep.c src/sys/i386/i386 mp_machdep.c

Maxim Sobolev sobomax at
Sat Nov 10 01:29:21 PST 2007

Bruce Evans wrote:
> Off is a good default since hyperthreading seems to be a pessimization
> in most casts.

Well, actually it all depends on workload and scheduling. I believe ULE 
is expected to improve things quite a bit in scheduling department. 
However, even with ol'good SCHED_BSD we measured noticeable performance 
increase (15-25%) in CPU intensive real-world tasks  with HTT enabled on 
2-way SMP Xeon system. It was in 2004, both CPUs and schedules should 
have been improved since that time.


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