On Mon, 2009-03-09 at 20:22 -0400, Tom Lane wrote: > "Patrick O'Callaghan" <pocallaghan@xxxxxxxxx> writes: > > On Mon, 2009-03-09 at 12:49 -0700, Adam Williamson wrote: > >> The most common CPU-bound operation in our world, I guess, is > >> compilation, and you would notice a definite improvement in speed there, > >> running x86-64 vs x86-32 - not huge, but noticeable. Certain database > >> and I think scientific operations that are CPU-bound also derive a > >> significant benefit. It depends on whether the code can take advantage > >> of much bigger registers, AIUI. > > > Anyone who does even casual video processing (e.g. with transcode > > filters) definitely will notice. This is something that pegs both cores > > to 100% when I run it, until the fan kicks in and it slows a bit. > > It's not so much about *bigger* registers as *more* registers. The > x86 architecture is incredibly register-starved (what comes of being > bug-compatible with a 1971 CPU design...). When AMD did the x86_64 > redesign they took advantage of the opportunity to define a more > reasonable number of registers. Avoiding swapping values in and out > to memory all the time is a large chunk of the reason for the > performance boost in x86_64 code. It's not uncommon for x86_64 > code to be physically smaller than comparable x86 code because of > elimination of those extra instructions, even though the individual > instructions tend to be wider. > > But I agree that a lot of people seldom do anything CPU-intensive > enough to notice. Video encoding is also one of the few things that may get a boost from the post-i586 instruction set enhancements (MMX, SSE, 3DNow!, all that crap), which can't be used in i586 packages but are used in x86-64 packages, as all x86-64 CPUs support them so it's safe. And yeah, Patrick, media encoding is probably the *second* most common high-CPU-use scenario in our world :) It's probably the most common scenario in the general set of computer users, actually. That's why Intel is forever harping on it in commercials. -- Adam Williamson Fedora QA Community Monkey IRC: adamw | Fedora Talk: adamwill AT fedoraproject DOT org http://www.happyassassin.net -- fedora-test-list mailing list fedora-test-list@xxxxxxxxxx To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-test-list
