News Focus
News Focus
icon url

Elmer Phud

06/26/03 11:32 AM

#7471 RE: Haddock #7469

Haddock -

Amazing what you can do when the entire benchmark fits in on-die cache!

I'm sure there will be plenty of other benchmarks on Monday.


icon url

wbmw

06/26/03 11:58 AM

#7474 RE: Haddock #7469

Haddock, Re: Amazing what you can do when the entire benchmark fits in on-die cache!

If that were the case, how does Power4 not do any better, given that it has 128MB of cache at its disposal?

Or to argue another way, consider the scalability of Madison over McKinley. 2x the cache and 50% more frequency yields about 46% in SPECfp. If the benchmark suddenly fit inside the cache where it did not before, then you would expect a much higher score, since cache latency is an order of magnitude better than memory latency. On the other hand, if the benchmark fit inside the cache in McKinley as well as Madison, you would expect a lower score, since SPECfp does not scale very well with frequency alone. The 46% improvement tells me that there is still a significant amount of the benchmark that resides outside the cache, but a higher hit rate allows better scalability than just the raw frequency boost.
icon url

jhalada

06/26/03 2:25 PM

#7510 RE: Haddock #7469

Haddock,

Time to go long SGI? Altix is pretty impressive. But then so is having a negative book value :-)

I guess these "commitments" to Itanium were not cheap.

Joe
icon url

chipguy

06/26/03 2:36 PM

#7511 RE: Haddock #7469

Amazing what you can do when the entire benchmark fits in on-die cache!

Nice theory but the only company that can come close to that is IBM with 128 MB
L3 in POWER4(+) systems.

http://www.specbench.org/cpu2000/analysis/memory/

SPEC CPU 2K was engineered to run on systems with a minium of 256 MB of
memory and blow past the 4 to 8 MB external caches common to high end RISC
systems of the late 1990s. Many component programs use 180-190 MB. Half the
programs use over 100 MB of memory when running. BTW, the next version of
SPEC CPU will likely increase memory usage by up to 4 or maybe even 8 fold.