Hennessy and Patterson

Ostensibly one of the most widely used books for studying computer architecture so I had a look, and... WTF? Possible future CPU designers are being fed with tripe like this?

http://i62.tinypic.com/xakqr.png

Despite all the focus on MIPS and performance, it is suspiciously missing any real benchmarks of MIPS processors.

They have an interesting definition of a "desktop computer":
http://i60.tinypic.com/4lq2j7.png

"Heineken and Pilsner" would be a better name for this book, as its authors appear to be as knowledgeable about real-world computer architecture as drunken fools.

>>24
15GB/s is good for nearly 600FPS of 24-bit 4096x2160 uncompressed video. Framebuffers don't need anywhere near that amount of bandwidth.

25

In that case the RISCs would've slowly evolved toward something with the complexity of x86 once they realised that the new bottleneck was memory bandwidth and not instruction decode/execute. Just look at all the instructions ARM have been adding, Thumb mode, etc.

Also got a chance to do this test on the Pentium MMX 200 (P54C), and it's different again from the P5s benchmarked above:

http://i58.tinypic.com/2jfjd3t.png

The MMX and FPU on this one is bloody fast at small sizes - we do see it beating REP MOVSD by ~2x - but using the registers, an unrolled loop using the registers (2x and 64x), and REP MOVSD are essentially identical in performance despite the unrolled loop being extremely cache-bloating. It looks like MOVSB/MOVSW haven't been optimised yet as they are definitely moving half and quarter as much data as MOVSD.

This is why CISC has so much potential. Complex instructions don't get slower, they get faster over time and give hardware designers more room to optimise with each new microarchitecture and make existing software faster. RISC is a dumb, overly simplistic, and ridiculously shortsighted design decision by people who don't understand the laws of physics.

I think all the claims of P&H have been thoroughly debunked now, unless anyone has a Sandy Bridge or newer and wants to test?