64-bit Kernel Question

Chris Adams cmadams at hiwaay.net
Mon Mar 9 18:51:22 UTC 2009


Once upon a time, Petrus de Calguarium <kwhiskerz at gmail.com> said:
> As memory requirements for 64-bit are anywhere from 50-100% greater and 
> the only appreciable difference is a "psychological" performance boost, what 
> REAL benefit is there, actually?

I don't "feel" that RAM requirements are that much greater in practice.
The virtual size is a lot higher for everything, but the actual resident
size is not.

There is a real performance boost, because the x86_64 architecture has a
larger register set than i386 (which is a relatively register starved
architecture).  This allows code to hit main memory less and run faster.

Also, as things grow and you add RAM, i386 tops out at 4G unless you use
PAE (which still has a 4G process-size limit and has a performance
impact), while x86_64 can handle much more RAM (more than any consumer
motherboard can hold today by far).  It may sound silly today, but RAM
usage is only going up (because programs do more, we run more programs
simultaneously, and because of ever-present bloat).

-- 
Chris Adams <cmadams at hiwaay.net>
Systems and Network Administrator - HiWAAY Internet Services
I don't speak for anybody but myself - that's enough trouble.




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