Re: Remote fork() and Parallel programming

Alan Cox (alan@lxorguk.ukuu.org.uk)
Mon, 15 Jun 1998 11:38:35 +0100 (BST)


> Process migration on SMP is a horrible idea. As I have mentioned
> repeatedly, read any one of the dozens of papers on a cache affinity.
> They all show how in almost all cases, the absolute worst thing you
> could do for performance is to reschedule a process on another CPU.

Its a matter of time scales. Leaving a cpu idle for 60 seconds with two
jobs on another CPU is bad on a conventional SMP box - by then cache
affinity is noise in the efficiency graph.

The same is going to be true for dynamic load balancing - if you are talking
about this sort of balancing on large enough timescales it will make sense
- true it may be every 30 minutes and you may try to do minimal movement

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