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SubjectRe: Ideas for reducing memory copying and zeroing times

Just as a point of reference, Sparc's previous to the recent
UltraSparc V9's could not do bcopy/bzero using floating point as
someone suggested could be done on the intel. The reason being is
that the fpu can only use the same speed load/store double-word
instructions to move values in and out of the fpu regs as the integer
unit can, so there would be no advantage. So what they did was add
special stream copy/fill hardware onto the Sparc which could do burst
copy/fill at full bus burst chunk size.

With the UltraSparc they have the same similar bcopy hardware
available but the FPU can be used efficiently now for such purposes
because there is a special load/store which can throw the entire
floating point register set to/from memory (64 64-bit registers ==
512k at a time).

Later,
David S. Miller
davem@caip.rutgers.edu


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