mtrr funnies

[Jerry Feldman]

Roger Heflin wrote:
>
> You can never generalize about 64bit is always faster, some are going
> to be faster on 32-bit (as you found) some are going to be faster on
> 64-bit, too many people assume that since 64-bit has more registers,
> and a few extra instructions that it is always faster than 32-bit.
Roger, I'm glad you posted this statement. I've worked in the 64-bit
world for over 10 years (Digital Alpha, PA-RISC, IA64, X86-64), and
there is some code that certainly performs better in 32-bit mode, not
only on X86-64, but in the other platforms.
In 64-bit, you not only have more registers, but memory addresses are
64-bit, so executables and libraries take more space, and context
switches require saving more registers.

-- 
Jerry Feldman <gaf at blu.org>
Boston Linux and Unix
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