On Sunday 31 August 2003 21:52, Filipe Joel Almeida wrote: <SNIP>
What are the major benefits of a 64 bit processor over a 32 bit processor?
Let's say for mail or Database server... would there be significant benefits from having a Dual Opteron over a Dual Xeon, and stuff like that?
Can anyone please shed some light on this subject?
SFAIUI, assuming you are running a 64bit OS with apps compiled for 64bit, then there are several ways that the apparent speed may be improved: - with 64-bit internal registers, number crunching can operate directly on larger values, so maths-intensive processes can obviously benefit. The Opteron and Athlon-64 also have a different memory access archetecture so fetch and put operations are (supposed to be) more efficient. - 64-bit Address registers means more memory is directly addressable, meaning that larger files (or portions of them) can be kept in RAM at a time. This meand a database (for example) can potentially have a 'live' copy of an entire (set of) table(s) im memory, rather than paging sections to disk, and that swap may become effectively redundant. Also, larger memory blocks are directly accessible, meaning that block operations can be performed on larger blocks of memory. This would also speed up databases, and especially graphics and video apps. - 64-bit instruction registers opens up a whole magnitude of space for new CPU instructions (in principle if not yet in practice) to allow the processor to do a wider range of operations as primitive instructions (for example, fetch, shift-left, put could be a single opcode instead of three) or provide for sub-instructions or parameterised instructions. All this means less instructions would need to be fetched to perform the same ammount of work. The AMD chips are backwards compatible, so they will run existing OS's (albeit in 32-bit state), and 32 (or even 16) -bit apps on 64bit OS's natively. The Intel offering is NOT backwards compatible in that it requires a 64 OS, but can run 32-bit apps (under a 64-bit OS) in a mode which emulates a 32-bit Intel chip. I'm sure there's other benefits as well... Dylan -- Sweet moderation Heart of this nation Desert us not We are between the wars - Billy Bragg