AEMB Benchmarked!

The AEMB has actually been benchmarked! I have claimed that the AEMB is the world’s fastest and smallest 32-bit multi-threaded RISC processor. Chapter 2 of this thesis put it in terms of real numbers!

Extracting the pertinent section of the results:

Name/Flipflops/LUTs/MHz
AEMB/711/926/279
LEON3/1133/3448/183
OpenFire/207/752/198
OpenRisc/1577/3802/185
Plasma/1297/2457/73

The AEMB has a MHz/LUT result of (0.3 MHz/LUT), which is way ahead of the rest. The thesis goes on to do a software Dhrystone and Fibonacci benchmark and found the performance to be good too.

Unfortunately, there were many issues faced during the implementation of the AEMB the resulted in the author dropping the use of the AEMB in favour of making a custom processor.

The main issue was that the author had difficulties targeting an ASIC platform because the AEMB was designed for the FPGA and optimised for an FPGA (which shows in the results). There were many design trade-offs that were made to make it very small and fast on an FPGA platform. Unfortunately, this is a show stopper as trying to port it to an ASIC technology would essentially require a redesign of the entire architecture.

There were other issues as well, including poor documentation and bad sample software. While I will agree with the part on poor documentation, I think that the author probably mistook the old AEMB sample software for the new AEMB sample software. This is something that can be avoided with better documentation to make it clear. So, ditto – it’s bad documentation. This needs to be fixed for the next generation.

Regardless, I’m happy that we can now put some numbers to my claims!

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Published by

Shawn Tan

Chip Doctor, Chartered Engineer, Entrepreneur, Law Graduate.

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