Date: Fri, 28 Sep 2001 07:43:47 -0600 From: "Kenneth D. Merry" <ken@kdm.org> To: Terry Lambert <tlambert2@mindspring.com> Cc: Jonathan Lemon <jlemon@flugsvamp.com>, the_srinivas@hotmail.com, hackers@FreeBSD.ORG Subject: Re: TCP&IP cksum offload on FreeBSD 4.2 Message-ID: <20010928074347.A36960@panzer.kdm.org> In-Reply-To: <3BB42E50.B32F5E95@mindspring.com>; from tlambert2@mindspring.com on Fri, Sep 28, 2001 at 01:01:20AM -0700 References: <200109270157.f8R1vZ546863@prism.flugsvamp.com> <3BB42E50.B32F5E95@mindspring.com>
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On Fri, Sep 28, 2001 at 01:01:20 -0700, Terry Lambert wrote: > Jonathan Lemon wrote: > > >I'm trying to use the TCP&IP checksum offload capability of the Netgear > > >GA620 NIC from a SMP FreeBSD 4.2R system running on a typical PIII SBC. > > >I did enable TCP&IP cksum offload for receive operations by setting the > > >if_hwassist flag in the driver /sys/pci/if_ti.c and verified that it is > > >working. However I'm unable to offload TCP&IP checksum for the send > > >operations. > > > > All you need to do is uncomment the TI_CSUM_FEATURES flag at the top > > of the file, and recompile. > > He didn't say his packet size, either. > > To the original poster: if you are sending jumbograms, the > buffer size on these cards is limited, so the entire packet > can't be in the card buffer at the same time, which means > that you can not offload the send checksum for jumbograms, > only for regular sized packets. You've got things confused. I think that may be a limitation of some SysKonnect boards, but certainly isn't a Tigon limitation. Tigon boards come with 512KB, 1MB, or 2MB (never seen one of these) of SRAM on board. The firmware takes a couple hundred KB, so you generally have at least 200KB, and possibly a good bit more for packet storage space on the card. So there is buffer space for a number of packets on both the send and receive sides, and checksumming works in both directions. > Also note that this card is not known to be the fastest > one ot there, so you may be better off doing the checksum > on your 1GHz+ host processor instead. You can get wire rate with a Tigon 2 board, with jumbo frames at least. (That's with checksum offloading enabled.) Ken -- Kenneth Merry ken@kdm.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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