Date: Sun, 23 Jan 2005 11:30:25 +0100 (CET) From: Sten Spans <sten@blinkenlights.nl> To: Scott Long <scottl@freebsd.org> Cc: freebsd-amd64@freebsd.org Subject: Re: Would this system work correctly with FreeBSD 5.3 ? Message-ID: <Pine.SOC.4.61.0501231126391.13561@tea.blinkenlights.nl> In-Reply-To: <41F31836.2010403@freebsd.org> References: <20050122141741.9690.qmail@web26804.mail.ukl.yahoo.com> <41F31836.2010403@freebsd.org>
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On Sat, 22 Jan 2005, Scott Long wrote: > Sten Spans wrote: > >> On Sat, 22 Jan 2005, Claus Guttesen wrote: > >> >> - Quad motherboards: >> It's a shame that tyan connects all >> the pci interfaces on their quad motherboard >> to one cpu. The hp/compaq quad proliant has >> seperate buses to two cpu's for extra bandwith. > > This is really academic right now since FreeBSD does not take > topology into account when making scheduling decisions or > routing interrupts. Without this affinity, it's only luck > if you happen to wind up on a CPU that is closer to the data. > Also, I don't believe that PCI buses are connected to CPUs > at all. They are connected via HT-PCI bridges that act as > normal HT peers. Only memory is connected directly to the CPU. > But I might be wrong. True, motherboards with this setup have extra ht-pci bridges. The amd reference motherboards have this design. But most motherboards don't use this setup to cut costs ( less bridges and traces needed ) and because it requires more cpu sockets to be populated ( although this isn't such a big problem on a quad motherboard ). -- Sten Spans "There is a crack in everything, that's how the light gets in." Leonard Cohen - Anthem
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