Ars Technica has an interesting article on a new 64-core CPU designed by Tilera. The TILE64 chip is aimed at embedded applications, so don’t expect to see it pop up in desktops anytime soon. However, Tilera claims that TILE64 is the “first significant new chip architectural development in a decade.” This new architecture appears to be based on a Raw concept pioneered by Tilera founder and MIT professor Dr. Anat Agarwal.
The basic idea behind Raw, a project that was started well before Moore’s Law stopped delivering huge clockspeed increases, was that as the number of transistors on a chip increases, wire delay becomes an architecturally significant factor in chip design. The Alpha 21164, Pentium 4, and PowerPC 970 are all examples of the first wave of commodity processors that had made major microarchitectural concessions (i.e., dedicated pipeline stages and increased load-use latencies for certain sequences of integer operations) for wire delay, but the effects of wire delay were still hidden from programmers as far as possible.
Agarwal’s idea was to expose wire delay to programmers via the ISA. The Raw project, the name of which seems to be a recursive acronym for “Raw Architecture Workstation,” exposes wire delay to the programmer as hops on an on-chip mesh network. It takes one cycle for data to move from one tile to the next, with the result that a compiler can statically schedule operations among multiple tiles’ ALUs by taking into account the exact number of cycles that it takes for a result to propagate across the chip.
TILE64 will debut at clock speeds between 600MHz and 900MHz and first be made available on PCI Express daughterboards.