question about Intel P4 versus Alpha's

[Henderson, TL Todd]

I've just put a new cluster in place and have been monitoring some things
via top and found something peculiar and was wondering what others thought.

I have an app, that scaled out to the 30ish XP1000's we had very nicely,
basically linearly.  If you looked at top, it was almost always in the
95-100%cpu utilization range.  However, now we have a cluster of P4's and
when I look at top, it is more like 70-80% cpu usage.  This is using the
same number of cpu's, the same switch, same code, and same problem for the
code.  The jobs are still completing in about 30-40% less time, so we are
getting a speed up.

My guesstimate was that this was an indication of the memory bandwidth and
speed to memory.  I know the XP1000's have a nice memory subsystem.  Was/is
it that much better than the 533/2.4 ghz P4's?

Any thoughts/comments/speculation?

Just curious.
Thanks,
Todd