On Sunday 31 August 2003 16:52, Filipe Joel Almeida wrote:
Well Adalberto, that was definitively a pretty good explanation!
Thanks :)
But personally I'm also curious about something else. I have asked this lots of times, one of them in this list, but noone has been able to give me a good answer.
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?
I think the great advantage is the increase in memory address space. Right now, linux running in x86 has a limit of 2GB (31 bits) of memory per process (no matter how much system memory you have). With substantial kernel meddling (don't have the refs at hand) apparently you can get to 3.5 GB per process. It's very easy to hit that barrier for some applications (big databases probably being one case). Speed wise, I don't see much benefit in the case at hand. I confess I'm not familiar with the opteron's architecture, but I assume it's little more than a wider athlon (as opposed to the itanium series, which is actually a very very different beast than the pentium - but even there the speed gains are hard to measure, since the performance depends a lot on compiler intelligence) which would explain why it can have a 32 bit 'mode' (according to a recent article in The Register, AMD is even going to start shipping 32 bit locked opterons under the Athlon XP label) where it is binary compatible with x86. So, no substantial speed gains should be expected there, besides the ones derived from Moore's law.