Date: Thu, 18 Jan 2007 21:01:41 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: Suleiman Souhlal <ssouhlal@FreeBSD.org> Cc: Maxim Sobolev <sobomax@FreeBSD.org>, Ivan Voras <ivoras@fer.hr>, Attilio Rao <attilio@FreeBSD.org>, freebsd-current@FreeBSD.org, freebsd-arch@FreeBSD.org Subject: Re: [PATCH] Mantaining turnstile aligned to 128 bytes in i386 CPUs Message-ID: <20070118204641.M3613@besplex.bde.org> In-Reply-To: <45AF23DE.6030801@FreeBSD.org> References: <3bbf2fe10607250813w8ff9e34pc505bf290e71758@mail.gmail.com> <3bbf2fe10607281004o6727e976h19ee7e054876f914@mail.gmail.com> <3bbf2fe10701160851r79b04464m2cbdbb7f644b22b6@mail.gmail.com> <20070116154258.568e1aaf@pleiades.nextvenue.com> <b1fa29170701161355lc021b90o35fa5f9acb5749d@mail.gmail.com> <eoji7s$cit$2@sea.gmane.org> <b1fa29170701161425n7bcfe1e5m1b8c671caf3758db@mail.gmail.com> <eojlnb$qje$1@sea.gmane.org> <3bbf2fe10701161525j6ad9292y93502b8df0f67aa9@mail.gmail.com> <45AD6DFA.6030808@FreeBSD.org> <3bbf2fe10701161655p5e686b52n7340b3100ecfab93@mail.gmail.com> <200701172022.l0HKMYV8053837@apollo.backplane.com> <20070118113831.A11834@delplex.bde.org> <45AF23DE.6030801@FreeBSD.org>
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On Wed, 17 Jan 2007, Suleiman Souhlal wrote: > Bruce Evans wrote: >> I haven't tried this, but have seen and partly worked sensitivity to >> linear KVA maps not being physically (non)linear enough. Some CPUs >> and/or memory systems are remarkably sensitive to bank interleave. >> FreeBSD's page coloring doesn't know anything about banks, ... > > About page coloring: Don't amd64 CPUs have virtually indexed, physically > tagged caches? If so, wouldn't it make sense to turn off page coloring, > since it's useless for virtually indexed caches (and probably hurts things > a bit)? I think superpages will soon turn off coloring. Not sure if this is right. How is copying and zeroing a whole superpage at a time avoided? IIRC, my benchmarks (and LMbench) show some small positive benefits for page coloring on amd64. I don't remember exactly what they are, just that they are smaller than on AthlonXP. Bruce
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