

The Problem with Larrabee: Memory bandwidth - bensummers
http://perilsofparallel.blogspot.com/2010/01/problem-with-larrabee.html

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jacquesm
I think the author is miscalculating the memory bandwidth requirements. There
is a big difference between hitting the cache and hitting main memory, and it
could very well be that what he interpreted as main memory accesses were in
fact meant as cache hits.

Given what we know about GDDR5 if Intel chooses to use a 512 bit wide
interface then at 900 Mhz you'd get 512/8 *.9 = 57.6GB/sec.

That's at 900 MHz, by upping that to 1066 you'd get 68.2 GB/sec.

High end graphics cards are now around 150 GBps, so larrabee is fast but not
requiring a revolution in memory architecture.

The fastest demoed version of larrabee was around 1Tflop, which in terms of
GPU performance puts it somewhere around december 2006, which is the major
reason it wasn't released, a high end Nvidia card does about 1.7.

