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Message
From: Joachim Strömbergson<Joachim.Strombergson@I...>
Date: Thu Jul 15 08:31:47 CEST 2004
Subject: [oc] Why open processors are so much slower than commercial ones?
Aloha!Mikhail Matusov wrote:
> Can someone explain why MicroBlaze seems to be so much
> faster than any of the free cores out there?
What do you mean with "faster"? Faster in terms of clock frequency or faster
in terms of execution performance i.e. efficiency?
Is it the first version, then, as others have stated, Xilinx have invested in
hand-mapping and tweaking the micro-arch to take advantage of the FPGA-arch,
something they should be the experts on.
You could/should be able to get very close if you did the same thing and
people have in fact designed processing elements (PEs) specifically for a
given FPGA-arch. Also, check out the work by Ray Andraka, who for many years
have hand tweaked DSP-cores for FPGA with impressive results:
http://www.andraka.com/
If it's the second version of "faster", then I'm not totally convinced that
OC-cores are that much worse. I've done some benchmarking of the OpenRisc and
it's not that bad, and part of that is quite probably also related to the code
generator in the compiler, not the core itself.
Also, if you look at, for example Alteras first Nios processor it actually had
a pretty inefficient API which resulted in big programs and low execution
performance. The new Nios II is *much* better. The MicroBlaze API is good, but
IMHO not mind bogglingly impressive and unique in terms of performance in the
world of processor cores.
--
Med vänlig hälsning, Yours
Joachim Strömbergson - Alltid i harmonisk svängning.
VP, Research & Development
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