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SubjectRe: Very high load on P4 machines with 2.4.28
Nicholas Berry wrote:
>>>>Willy Tarreau <willy@w.ods.org> 01/04/05 5:05 PM >>>
>>>
>>>Oh, while I'm at it, are you using hyperthreading, and if so, could
>
> you
>
>>>disable it ? I have seen many cases where it degrades performances
>>>significantly (eg: highly loaded user space network applications).
>
>
> Indeed. AIX (sorry) 5.3 on POWER5 explicitly disables SMT (IBM
> hyperthreading) if the load doesn't warrant it.
>
> (Now how about that for Linux?) :)

Didn't he say that it degrades performance under load? You're asking to
disable it under low load. The 2.6 scheduler is already supposed to try
and move tasks to full cores if they're empty instead of smt siblings.

Con
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