About 10 years ago, I was in charge of the product definition of our next IP to be released, the PCI Express gen-1 Controller. I was also involved in the decision process to select the new functions to develop, in respect with the market size, all of this being the definition of “marketing”. The reason why our company decided not to develop Serial RapidIO was because the engineering team was far too busy (PCIe IP sales were exploding). At that time, we also had Hyper Transport protocol in the radar. Fortunately, we did not select Hyper Transport, but we may have decided to add Serial RapidIO to our port-folio. Serial RapidIO is very complementary with PCI Express, as the protocol’s strengths are the PCIe’s weaknesses:
- Serial RapidIO offers a very low latency (compared with PCIe, and Ethernet)
- Serial RapidIO is a “routable” protocol: it can be used to interconnect a (very) large number of processors together (when PCI Express native topology is based on a tree: one Root agent is interconnected to several Endpoints)
If you want to dig more, and better understand the differences between PCI Express, RapidIO and Ethernet, you will find an excellent article, on RapidIO web site, in Technology Comparison section. The article is written by Sam Fuller, and Sam was a founder of the RapidIO Trade Association and now serves as Head of System Solutions, Digital Networking at Freescale Semiconductor.
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