Date: Wed, 30 May 2001 08:51:55 -0700 From: Brooks Davis <brooks@one-eyed-alien.net> To: Bob Willcox <bob@immure.com> Cc: Giorgos Keramidas <keramidi@otenet.gr>, Jesper Skriver <jesper@skriver.dk>, hackers list <freebsd-hackers@FreeBSD.ORG> Subject: Re: How to disable software TCP checksumming? Message-ID: <20010530085155.B24096@Odin.AC.HMC.Edu> In-Reply-To: <20010529235215.A60177@luke.immure.com>; from bob@immure.com on Tue, May 29, 2001 at 11:52:15PM -0500 References: <20010529144114.I19771@luke.immure.com> <20010529221107.C49875@skriver.dk> <20010529155212.M19771@luke.immure.com> <20010530045200.A1031@hades.hell.gr> <20010529235215.A60177@luke.immure.com>
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--9zSXsLTf0vkW971A Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, May 29, 2001 at 11:52:15PM -0500, Bob Willcox wrote: > This is probably all well and good, but our adapter is a 10 Gb/s link > and includes hardware CRC (actually two forms of this, LCRC on a per > micropacket [32 byte] basis and ECRC over the entire message). Right > now our goal is to see how fast we can get it to run on PC hardware > on FreeBSD with IP. We don't really expect IP to allow us to reach > it's theoretical limit of about 800 MB/s, but the closer we can get the > better. :-) (ST and a system with faster main memory and dual PCI-X > busses should allow us to get much closer.) I was just thinking I wanted this feature for a cluster. I was thinking the knob should be three state. Default, on for all packets. Next, off for localy connected networks and finally, off for all packets. For what it's worth, I agree it's just a waste of CPU to checksum TCP packets that will only travel over 1Gb or 10Gb Ethernet, or similar links. This 10Gb Ethernet presentation talkes about mean time between false packet acceptance being around 60 billion years: http://www.best.com/~walker/pdfs.talks/albuquerque.pdf -- Brooks --=20 Any statement of the form "X is the one, true Y" is FALSE. PGP fingerprint 655D 519C 26A7 82E7 2529 9BF0 5D8E 8BE9 F238 1AD4 --9zSXsLTf0vkW971A Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.4 (GNU/Linux) Comment: For info see http://www.gnupg.org iD8DBQE7FRcaXY6L6fI4GtQRAqgeAJ4thoJt/5xicuyWUUQhRS6O0jHdEQCgmwzC e1lM4UNkutpLfOG1d8XbHUY= =C65S -----END PGP SIGNATURE----- --9zSXsLTf0vkW971A-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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