Benchmarks: AMD64 vs i386 on Dual 246 Opteron

[Dag-Erling Smørgrav]

ray at redshift.com writes:
> While this sounded like a long shot, I loaded FreeBSD 5.4 i386 on
> the machine and after applying the exact same configuration to the
> OS, Apache, PHP and MySQL, re-ran the benchmarks.  Much to my
> surprise, just changing the OS from 64 bit to 32 bit caused the
> machine to double in speed.  The results are attached in an Excel
> spreadsheet.  So the exact same machine, running the identical
> configuration, performed roughly twice as fast when running FreeBSD
> 5.4 i386 vs FreeBSD 5.4 AMD64.  Something about this seems so wrong
> to me :-)

64-bit code uses up to twice as much CPU cache and twice as many
memory accesses to do the same work as the equivalent 32-bit code.

DES
-- 
Dag-Erling Smørgrav - des at des.no