[ale] mosix clusters?

[Jeff Hubbs]

On Sun, 2002-06-23 at 23:12, Joseph A Knapka wrote:
> Jeff Hubbs wrote:
> > 
> > To revisit a bit, you'd need to know if, on a given 1-CPU machine, two
> > SAH WUs run at once is faster than, slower than, or as fast as two WUs
> > run end-to-end in the typical fashion.  If it's slower, then there is
> > absolutely nothing to be gained by running more SAH WUs at once than you
> > have CPUs.  My experience suggests that it would be slower, implying
> > that one instance per CPU is OPTIMAL; I say this because on a 2-CPU
> > machine, both CPUs get saturated, which tells me that memory I/O is not
> > an issue.  One instance per CPU is no different than what I do on every
> > machine I can get my hands on, Mosix-less.
> 
> Surely it is impossible for two WUs to run simultaneously on
> a single-CPU box in less time than they would run serially,
> since in the simultaneous case both WUs would presumably
> always be runnable, and thus you'd have context-switch
> overhead that wouldn't be present if single WU were the
> only runnable process on the box.
> 

Joe -

That's what I would assume as well.  I don't have the 'fu to know just
how much context-switching overhead that would entail.  I do wonder,
though, if there might be some "sweet spot" that takes advantage of the
way the processes use the CPU/mobo architecture, what with instruction
pipelining and L1/L2 cache.  


---
This message has been sent through the ALE general discussion list.
See http://www.ale.org/mailing-lists.shtml for more info. Problems should be 
sent to listmaster at ale dot org.