On Mon, 2009-03-09 at 12:54 -0600, Kevin DeKorte wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Petrus de Calguarium wrote: > > So, there has been a lot of discussion and information about this issue. I > > am presently burning the DVD, might buy another 2 GB of RAM, and am about > > to commence installing the x86_64 version of F11alpha to a spare partition. > > > > Now, I have another question, having arisen out of this discussion (and not > > precluding others that could easily arise, once I have a running system): > > > > As memory requirements for 64-bit are anywhere from 50-100% greater and > > the only appreciable difference is a "psychological" performance boost, what > > REAL benefit is there, actually? > > > > > > 64bit processors generally have more registers to work with, so you can > get 10-20% speed increases when the compiler takes advantage of them, > and I believe gcc does. That depends on the architecture family. This is true for x86 vs. x86_64 because the 32-bit x86 family is so register-starved. AMD chose to fix this when they developed the x86_64 ISA and added all the extra registers. Otoh, on PPC/PPC64 this isn't true. The 32-bit CPUs/modes have exactly the same number of GPRs as the 64-bit versions so this benefit does not exist there. That's why Fedora/RHEL on 64-bit ppc has a mostly 32-bit userland: there's no benefit to using 64-bit processes unless they really do require the larger address space possible with 64-bit addressing (the 64-bit -libs and -devel packages are included for this reason). Regards, Bryn. -- fedora-test-list mailing list fedora-test-list@xxxxxxxxxx To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-test-list
