Title: Re: [PERFORM] 64-bit vs 32-bit performance ... backwards?
Opteron is ~20% faster at executing code in 64-bit mode than 32-bit because of the extra registers made available with their 64-bit mode:
http://www.tomshardware.com/2003/04/22/duel_of_the_titans/page7.html
Doubling the GPRs from 8 to 16 has generally made a 20%-30% difference in CPU-bound work:
http://www.tomshardware.com/2003/04/22/duel_of_the_titans/page18.html
If the task is memory bandwidth bound, there should be an advantage to using less memory for the same task, but if the database is using types that are the same width for either execution mode, you wouldn't expect a significant difference just from wider pointer arithmetic.
- Luke
