[Beowulf] Opinions of Hyper-threading?
landman at scalableinformatics.com
Tue Feb 26 13:42:05 PST 2008
Bruno Coutinho wrote:
> Yes, and more than an out of order processor. A out of order processor,
> can reorder the instructions whenever a hazard occurs. A in order
> processor, on the other hand, has to wait. With SMT, it can switch to
> another thread.
> And today memory access can stall up to hundreds of cycles, so any
> processor can hide this latency by switching to another thread.
My gosh ... we have re-invented the Tera MTA. ...
> But the you have to make sure the processor has enough cache and memory
> bandwidth to handle the increased memory traffic (like Sun Niagara).
The problem with many (cores|threads) is that memory bandwidth wall. A
fixed size (B) pipe to memory, with N requesters on that pipe ...
Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics LLC,
email: landman at scalableinformatics.com
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