Date: Thu, 15 Nov 2007 16:26:46 -0800 From: "Jack Vogel" <jfvogel@gmail.com> To: "Andre Oppermann" <andre@freebsd.org> Cc: freebsd-net@freebsd.org, Scott Ullrich <sullrich@gmail.com>, freebsd-current@freebsd.org, Julian Elischer <julian@elischer.org>, "Wilkinson, Alex" <Alex.Wilkinson@dsto.defence.gov.au> Subject: Re: I/OAT ... Coming Soon ? Message-ID: <2a41acea0711151626u99fb8e5l55bf5159fb808a01@mail.gmail.com> In-Reply-To: <2a41acea0711151625q5a994cf3ja0d5f14b0670ca3@mail.gmail.com> References: <d5992baf0711150913n6eb31751q8f210e89e5feb2ab@mail.gmail.com> <200711151729.lAFHTbiq024351@ambrisko.com> <d5992baf0711150952g6aca6d95g80f2ea778125d2d9@mail.gmail.com> <473CE2B9.8010201@freebsd.org> <2a41acea0711151625q5a994cf3ja0d5f14b0670ca3@mail.gmail.com>
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On Nov 15, 2007 4:25 PM, Jack Vogel <jfvogel@gmail.com> wrote: > > On Nov 15, 2007 4:22 PM, Andre Oppermann <andre@freebsd.org> wrote: > > > > Scott Ullrich wrote: > > > On 11/15/07, Doug Ambrisko <ambrisko@ambrisko.com> wrote: > > >> Hmm, I forgot about the 2970 which are AMD based. Can you check the > > >> BIOS to see if there is an option to turn it on? I think this is an > > >> Intel feature. AMD might have something close? We have one 2970 > > >> that we've played with a little but not much. I can't say for sure > > >> if it has it. > > > > > > Right you are. As of BIOS 1.2.2 I do not see a I/OAT option. Guess > > > I will need to pick up a different server as we are interested in what > > > kind of packet forwarding rate increase that this feature might bring > > > on a heavily loaded firewall. > > > > Not much. Unless your firewall is in usermode. Otherwise the data > > stays in the kernel and I/OAT is of not help as no copying happens. > > Your CPU is probably spending half of its clock cycles waiting on > > cache misses from newly arrived packets. Some Intel chipset integrated > > gige ports have a cache prefetch feature (duno whether our driver > > supports it) that would help quite a bit for your case. > > What might help this is multiqueue support on the receive AND send, > and stack support for the same. Not sure what the stack changes > would look like, but I know there's interest in this sort of thing, so > naturally I'd be into it :) > > Jack > OH, and I should quickly add, that this only makes sense with hardware that supports it, ie with MSI/X. Jack
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