"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. regards, tom lane -- fedora-test-list mailing list fedora-test-list@xxxxxxxxxx To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-test-list
