Messages in this thread | | | Date | Wed, 5 Jan 2005 00:05:45 +0100 (CET) | From | Jesper Juhl <> | Subject | Re: Very high load on P4 machines with 2.4.28 |
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On Tue, 4 Jan 2005, 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). > > >Willy > > Indeed. AIX (sorry) 5.3 on POWER5 explicitly disables SMT (IBM > hyperthreading) if the load doesn't warrant it. > Heh, yeah, that's pretty funky. I was initially pretty baffled first time topas on a AIX 5.3 box showed me I had 6 CPU's but quitting it and starting it 2sec later showed me 8 CPU's (box has 4 physical CPUs). That send me hunting through docs. On the surface it seems like a nice feature, but if it makes any real difference or not I've had difficulty in determining.
-- Jesper Juhl
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