On Thu, Dec 14, 2006 at 02:56:37PM -0800, Mark Crispin wrote: > Actually, what is it about 64-bit mode that people need? The list of > benefits that I can come up with: > . more address space if the application needs more than 4GB of VM > . faster arithmetic with integers greater than 2^31-1 (or 2^32-1 for > unsigned ints) > . faster arithmetic with high-precision floats (I agree that 32-bits > is woefully inadequate for floats). > . easier handling of long-file support (which is a separate issue, > and the mix format is probably a better solution for the large > mailbox problem than long-file flat files).
My understanding is that on the amd64 architecture, they also increased the number of CPU registers by 8 (from 8 to 16, i believe) vs. the 32-bit x86. I am not a CPU bit-head but I can imagine this could make a significant difference in the performance on (even integer) cpu-intensive operations. I am even less a compiler internals guy but I can imagine that this didn't require a lot of effort for the compiler to be modified to take advantage of. the extra registers are unavailable in 32-bit compatibility mode, even when running a 64-bit OS. This doesn't apply to the gentleman who's posting about his SPARC systems but it does apply to most of us. regarding apache/php, my experience is that PHP is a PIG and can use any extra CPU performance it can get. here's one reference that mentions this: http://www.pcstats.com/articleview.cfm?articleid=1466&page=3 danno -- Dan Pritts, System Administrator Internet2 office: +1-734-352-4953 | mobile: +1-734-834-7224 _______________________________________________ Imap-uw mailing list Imap-uw@u.washington.edu https://mailman1.u.washington.edu/mailman/listinfo/imap-uw
