On Mon, Apr 06, 2009 at 11:30:47AM +0100, psmith wrote: > Will Woods wrote: >> On Sun, 2009-04-05 at 23:01 +0100, psmith wrote: >> >> >>> i completely understand the reasoning to move i365 up to i586, but >>> why on earth restrict i686 capable processors to the i586 instruction >>> sets? >>> >> >> Again: the only difference between i586 and i686 is the CMOV family of >> instructions, which are generally *slower* than the i586 version. >> >> You can read Linus' detailed explanation here: >> http://ondioline.org/mail/cmov-a-bad-idea-on-out-of-order-cpus >> >> Building for i686 gives *no* real performance benefit[1], but breaks >> support for i586 machines - Via C7-based netbooks, AMD Geode (e.g. the >> OLPC XO-1), and so on. >> >> -w >> >> [1] except on in-order CPUs like Atom and the original Pentium >> >> > well i understand why fedora stuck with downgrading to i586 now, saving > work by only having to compile 1 kernel version for the x86 arch (plus > to keep the olpc folks happy i suppose) and while linus is undoubtably a > clever guy i think intel know their arch better than anyone, and if cmov > was a performance hit it would be removed ;) looks like i'll need to > compile my own i686 for my aspire one as the i586 kernel in F11 beta is > showing a noticeable performance hit over F10 i686 :( You can use the i686-PAE kernel on your Atom-based netbook. Regards, R. -- Dominik 'Rathann' Mierzejewski <rathann*at*icm.edu.pl> | LAN Staff Interdisciplinary Centre for Mathematical and Computational Modelling Warsaw University | http://www.icm.edu.pl | tel. +48 (22) 5540810 -- fedora-test-list mailing list fedora-test-list@xxxxxxxxxx To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-test-list
