[plug] SMP vs memory, was: *athon

[Mike Holland]

On Fri, 23 Jul 1999, Greg Mildenhall wrote:

> > Yes, and I'm saying the thrashing process shouldnt affect the others,
> > _unless_it_is_swapping_.

> Close but no cigar. You also have to consider cache-thrashing, since the
> process moves from a CPU whose cache has what the program needs in it, to
> another CPU that has been running a different task. Shifting all that data
> back and forth between the caches has a very bad effect on performance
> - not as bad as swapping, but you can't get rid of it by adding more RAM.

Interesting. What size time-slice is used by Linux?
I would have thought that it was kept big enough to keep the average
hit-ratio reasonably high.
  Is there more than one cache level on a PII, Celeron, or PIII ?

> Linux SMP is not really tuned for a desktop.

I was describing a single-CPU example.

> It does help, because it reducing cache-thrashing, as long as the
> scheduler doesn't bounce the CPU-hog back and forth between processors.

Thanks.

Mike Holland <mike at golden.wattle.id.au>            Perth, Australia.
                          --==--
	"Disraeli was pretty close: actually, there are Lies, Damn lies,
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