Joe Landman wrote:

>4-threads
>
>Copy:        6645.4125       0.0965       0.0963       0.0976
>Scale:       6994.6233       0.0916       0.0915       0.0917
>Add:         6373.0207       0.1508       0.1506       0.1509
>Triad:       6710.7522       0.1432       0.1431       0.1433
>
>I may have been Bill's 10 GB/s source, and that may have been a mixup on my part.

10 GB/sec of course comes from the advertised bandwidth off a single socket.

Yes, this is quite disappointing because the "on-paper" numbers from each
socket to the Northbridge are nicely balanced with the 4-channel FB-DIMM
numbers. Then there is all the discussion of the advantages of the shared L2 cache and the shared-cache-intelligent pre-fetch engines and cool memory dis-ambiguation.
Seemingly irrelevant I guess, if the Northbridge is still under designed.

Is it possible that the compilers are just not ready to effectively use some of these features ... ?? ... on the other hand stream is sufficiently simple that these features probably do not come into play anyway. The real application benchmarks with
some quantity of locality look better.

Any one working on compilers care to comment what's the bottleneck really is?

rbw






--

Richard B. Walsh

Project Manager
Network Computing Services, Inc.
Army High Performance Computing Research Center (AHPCRC)
[EMAIL PROTECTED]  |  612.337.3467

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