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What you need to know about Intel's Nehalem CPU

@ 2008/04/09

In this article, I'll give a general overview of Nehalem, focusing on the major changes and big new features that the architecture will eventually bring to Intel's entire x86 processor line. A more in-depth examination of Nehalem from me will show up later in the spring; for now, read on for the highlights. Here's what you need to know about Nehalem.

Comment from Kougar @ 2008/04/14

Quote:

Originally Posted by jmke

doesn't 64-bit improvements come from applications written especially for 64-bit, which take advantage of the upgraded architecture ?

Not sure the program must be natively 64bit to see an improvement. If I understand this Nehalem will simply act upon several specific 64bit instruction sets, and fuse them together for processing in half the time. Same principle as the current 32bit macrofusion. Except with Core 2 Duo 64bit instructions are first split into 32+32, then processed.

64bit applications on 64bit Operating Systems would no longer need to be split into 32bit+32bit. Instead, select 64+64 instruction sets would be processed in the same clock cycle previously taken to process a 32+32bit (A single split 64bit) instruction set. Or am I wrong?

Comment from Rutar @ 2008/04/14

What we need to know? It made the CTO of AMD resign =P

Comment from jmke @ 2008/04/14

doesn't 64-bit improvements come from applications written especially for 64-bit, which take advantage of the upgraded architecture ?

Comment from Kougar @ 2008/04/14

Great article. I didn't realize the changes were quite so numerous such as the loop stream detector.

Quote:

Nehalem widens the number of x86 instructions that can be macrofused in two ways. First, it expands four new compare + jump branch conditions to the list of macrofusable instruction pairs. Second—and this is major—it can now macrofuse 64-bit instructions

Macrofusion is partly what gives C2D it's performance advantage, it will be very interesting to see if this new 64-bit capable version means 64-bit OS's will offer better performance at long last?

I still am still betting QPI is going to show a significant performance improvement with the Nehalem generation thanks to all these changes. SMT should actually be useful this time around.

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