Messages in this thread | | | Date | Fri, 9 Apr 1999 19:49:20 -0400 (EDT) | From | Gregory Maxwell <> | Subject | Re: CPU affinity |
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On Sat, 10 Apr 1999, Orlando Andico wrote:
> > Hello all, > > Are there any patches available to enable some sort of CPU affinity? this > would be useful for some software (e.g. Informix Dynamic Server) and in > general would reduce cache thrashing on SMP boxes.
Linux already uses a simple form of CPU affinity. Although it is quite simple, it is quite effective. I worked on it for about a week somewhere around 2.1.4x and was unable to acheve any intresting improvements.
With more complicated schemes I had the following problems:
1) The added computation time outweighed the benifit. 2) The 'smart' method slowed cpu load imbalance rebalencing and slowed things down. or 3) It broke even.
However, this was on a Dual P5/166MMX with a combined L2 cache. On PPRO+ the L2 caches are seperate so better affinity gives you a bigger win. I havn't done any expirmentation on PPRO+ SMP systems, so it might be a win there...
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