On Sat, Sep 02, 2006 at 12:38:45AM +0200, [EMAIL PROTECTED] wrote: > U?ytkownik edwardsa <[EMAIL PROTECTED]> napisa?: > >I have a question about your claim of performance degradation. See below. > > > ... > > >Is this degradation true for all applications? To be clear, are you > >saying that if > >I compile a fortran code using either pgi, or the 64-bit libraries of > >g77, that it will run more slowly on a 32-bit compatible distro than it > >will on a pure-64 bit Debian? > >If so, why? > > I wrote: "...as someone mentioned here some time ago, this 32bit > compatiblity makes them slower than pure 64bit debian..." > > But it turned out that no one mentioned it here (on the list) - I searched > the list archive and havent found the info and have just remembered that > I read it here: > https://alioth.debian.org/docman/view.php/30192/21/debian-amd64-howto.html#id272321 > > Quote: > "...While architectures like sparc64 or powerpc64, which provide lib for > default 32bit libraries and lib64 for extra 64bit libraries, default to > executing 32bit applications, amd64 defaults to 64bit binaries because of > the performance benefits it offers in 64bit mode..." > > So I don't know exactly what are the benefits, but am beliving what was > written on the above given site. And I don't know why there is a > performance degradation.
I think they are referring to comparison between 32- and 64-bit applications. If the word size were half, then data is moved more slowly from memory. Also, 64-bit may have a much richer set of machine instructions so that a given operation can take one clock cycle in 64-bit mode where it might take multiple cycles in 32-bit. If I'm right, then I don't think that there would be any degradation on a distro with mixed 32/64 bit libraries, compared to debian's preference for a chroot. It's more a question of organization. Art Edwards -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
