Linked by Tony Bourke on Thu 22nd Jan 2004 21:29 UTC
Benchmarks When running tests, installing operating systems, and compiling software for my Ultra 5, I came to the stunning realization that hey, this system is 64-bit, and all of the operating systems I installed on this Ultra 5 (can) run in 64-bit mode.
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Re: Responses
by Gandalf on Fri 23rd Jan 2004 00:18 UTC

> What you said is not true. On everything >= SuperSPARC and everything >= i387, the FPU is at least 64-bits.

I didn't deny that. Actually quite the opposite.
Often it's 80bit or even 128bit.

FPU Datatypes (differ from platform to platform):

float: most often 32bit
double: >= 64bit (eg. on ix86 it's 80bit internally)
long double: 80bit or 128bit

But ... the load/store of the 64bit/128bit values is slower for 32bit builds than for 64bit builds, amongst other things (eg. conversation etc.)

The performance for >=64bit floating point arithmetic (at least double precision) is *slower* for 32bit systems than on 64bit systems. It's not a huge difference, but noticable.