[Linux-ia64] Itanium gets supercomputing software
rbw at ahpcrc.org
Tue Apr 15 11:08:20 EDT 2003
On Tue Apr 15 09:45:03 2003, Joseph Landman wrote:
>I remember the Trace Multiflow in 1991 or so, where compiling my
>molecular dynamics code took the better part of a day. Made debugging
>interesting, as the "bug" only appeared in the optimized code.
Don't think EPIC compile times compare to those of the MultiFlow, but
I have no direct experience.
I do think EPIC is valuable on several scores. First, it frees real
estate on the chip by reducing/eliminatin out-of-order execution hardware
allowing for larger caches (3 MB on chip today) and future additional
functional unit parallelism or additional cores on the same chip. Second,
it allows generated code to be tuned to the width (number of simultaneous
instructions alowed) of the processor. Finally, its predicate/nat analysis
can completely remove traditional stall points where the CPU must wait
for data from memory or conditions to be computed before proceeding to
execution. The last advantage is a useful way of using increasingly
redundant core hardware to speed results through the processor. "Micro-
threads/paths" are simultaneously computed using hardware that for the
moment would be idle anyway and results that are later proven to
to un-needed are be discarded.
The benefits are hard to quantify, but I believe significant part
of the I2's SpecFP score is EPIC derived.
I am guessing others disagree ... ;-) ... Oui?
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