On Thu, 29 Jun 2006 01:40:50 PDT, Paul Jackson said:

> Jay - what happens if we have 1024 CPUs (the current default config
> for ia64/sn2)?
> 
> My naive expectation would be that the rate of exits/sec would go up as
> the number of CPUs. In other words, I'd expect the exits/sec/CPU to be
> a rough constant, slowly increasing over the years as the CPU clock
> rate goes up.

You're probably correct on that model. However, it all depends on the actual
workload. Are people who actually have large-CPU (>256) systems actually
running fork()-heavy things like webservers on them, or are they running things
like database servers and computations, which tend to have persistent
processes?

Of course, I'm biased by my environment - the big Mac cluster and 2 larger SGI
boxes we have quite likely spend hours at a time where the exit/sec for the
entire image is in the single and low double digits, and the per-cpu value
is down in the noise.  But they're pure machoflops boxes....