by Greg Pfister
The recent near-simultaneous announcements of IBM’s POWER7 and Intel’s Itanium 9300 (”Tukwila”) invites some background on how those differ in essential architecture, why VLIW (Itaniam’s architecture) never was a good idea in the first place, and how they compare to the alternative simple multicore systems such as Sun’s (now Oracle’s) Niagara.

Why do this when this blog is about parallel stuff, and they’re all, except Sun, devoted to single-stream performance? This isn’t “The Perils of Serial,” and won’t become that, but it nevertheless is wise to know thy enemy. Besides, it will explain what “small simple core” really means compared with the alternatives.

So: POWER is Superscalar, Itanium is VLIW (Very Long Instruction Word; Intel calls its version EPIC for Explicitly Parallel Instruction Computer), and Niagara is composed of many simple cores.

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