Re: Very high load on P4 machines with 2.4.28

From: Con Kolivas
Date: Tue Jan 04 2005 - 20:42:34 EST


Nicholas Berry wrote:
Willy Tarreau <willy@xxxxxxxxx> 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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