Date: Mon, 17 Dec 2007 13:01:59 -0800 From: "David Christensen" <davidch@broadcom.com> To: darrenr@freebsd.org, "Kip Macy" <kip.macy@gmail.com> Cc: FreeBSD Current <freebsd-current@freebsd.org>, Robert Watson <rwatson@freebsd.org>, freebsd-arch@freebsd.org Subject: RE: pending changes for TOE support Message-ID: <09BFF2FA5EAB4A45B6655E151BBDD903068DBCBF@NT-IRVA-0750.brcm.ad.broadcom.com> In-Reply-To: <4764EDD0.5050101@freebsd.org> References: <b1fa29170712121303x537fd11fj4b8827bb353ad8e4@mail.gmail.com> <b1fa29170712150057m690bd36bm7a1910969e92293b@mail.gmail.com> <20071215100351.Q70617@fledge.watson.org> <b1fa29170712151040icb371efseaf61d9b79907b24@mail.gmail.com> <4764EDD0.5050101@freebsd.org>
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> >> + * The TOE API assumes that the tcp offload engine can offload the > >> + * the entire connection from set up to teardown, with > some provision > >> + * being made to allowing the software stack to handle > time wait. If > >> + * the device does not meet these criteria, it is the > driver's responsibility > >> + * to overload the functions that it needs to in > tcp_usrreqs and make > >> + * its own calls to tcp_output if it needs to do so. > >> > >> While I'm familiar with TCP, I'm less familiar with the > scope of what cards > >> support for TOE. Do we know of any cards that are less > capable than the > >> chelsio card in this respect, or are they all sort of > on-par on that front? > >> I.e., do we think the above eventuality is likely? > > > > I don't have any way of knowing. I think it is probably safe to say > > that any vendors that don't meet that criteria now will in > the future > > as transistor density increases. > > There are cards (or at least I've heard talk of this) that do partial > TCP offload - that is the connection setup and teardown are handled by > the operating system and that only data transfer is offloaded. I'm in > the wrong country to chase down details on this ;( You are referring to Microsoft Chimney architecture which would be supported by all TOE adapters that operate under Windows (our NetXtreme II controllers included). There are IP issues related to a chimney style implementation that would likely preclude their use under FreeBSD including passing TCP state information between the host OS and the controller among them. Davehome | help
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