SUMMARY : Sparc 2000E --> UE6000 / What performance gains ??

Date: Wed Nov 11 1998 - 23:30:58 CST

WOW you guys are fast and good !! Below is a copy of my original question
and then a brief summary of the key points made in my responses ...

=======================8< BEGIN Original Question 8<=======================

> Hello Sun Managers,
> We have a Sparc 2000E with:
> (16) 60-MHz CPUs each with 2MB cache
> 3 Gig of RAM
> (2) XDBuses
> System clock frequency 50 MHz
> vmstat output NEVER shows the CPU %idle to be 0%, as a matter of fact it
> always above 10% idle. vmstat output looks to be normal (45% User, 35%
> system, 0% Wait I/O, and 20% idle with 0 jobs in the run queue). Without
> passing every piece of information, there are no obvious CPU, memory,
> network, or I/O bottlenecks. mpstat does not show any large fluctuation
> changes in any values (strangely the cross calls - xcal is always 0, I
> would expect a few xcals every now and then for a system with 16 CPUs).
> While I understand that code optimization is where we can expect to see
> largest gains in performance, we are getting ready to replace the Sparc
> 2000E with a new UE6000 with
> (16) 336-MHz CPUs each with 4 MB cache
> 3 Gig of RAM
> If the application is not stressing the current Sparc 2000E, as
> defined by vmstat ouput, I believe our gains will be minimal with the new
> UE6000, is this true ?? From a performance stand point, what gains can
> expected ??

=======================8< END Original Question 8<=======================

1) Looking at vmstat %idle for a 16-CPU system can be misleading when
trying to measure a system's CPU performance. A better solution is to look
at the output of mpstat, which gives %idle for each processor, and make
sure that the work load is evenly balanced among all processors.

2) The gains will depend on the application - individual processes or
threads will run approximately 5 times faster ( 60 --> 336 ). If you have
a CPU-intensive task that does not scale well (or at all) on a system with
multiple processors (such as program compiles), these processes will be
much faster. If the application is truely 100% scalable among processors
on a multi-processor system, you may not see huge performance gains, but
single threaded applications will benefit from the processor upgrade.

3) Xcals typically exists when a system is not busy, no Xcals implies very
good scheduling and very little shared memory usage.

4) The new 336 MHz processors contain 4MB of cache (as opposed to 2MB of
cache on the current 60 MHz processors). This additional cache will help
with DNLC hit rate. When the new processors "miss" on the DNLC the new UPA
bus (backplane on the UE6000s) will handle the miss much quicker than the
XDbus (backplane on the Sparc 2000E). These in turn will improve the
performance of your system.

I should also point out that several people mentioned the fact that Sun is
about to release thier 400 MHz processors.

Thanks to the many who replied, with special thanks to:

Peter Polasek
Kevin Sheehan

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