Date: Wed, 13 Sep 2006 10:46:22 -0500 From: Brooks Davis <brooks@one-eyed-alien.net> To: John Baldwin <jhb@freebsd.org> Cc: Andre Oppermann <andre@freebsd.org>, current@freebsd.org, Mike Tancsa <mike@sentex.net>, Ian FREISLICH <if@hetzner.co.za>, freebsd-current@freebsd.org, Jack Vogel <jfvogel@gmail.com> Subject: Re: TSO, SMP and the em driver. Message-ID: <20060913154622.GA52716@lor.one-eyed-alien.net> In-Reply-To: <200609131108.45382.jhb@freebsd.org> References: <E1GN5FA-00085C-CJ@hetzner.co.za> <7.0.1.0.0.20060912125903.15bdb7a0@sentex.net> <45073F58.6080900@freebsd.org> <200609131108.45382.jhb@freebsd.org>
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--3V7upXqbjpZ4EhLz Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Sep 13, 2006 at 11:08:44AM -0400, John Baldwin wrote: > On Tuesday 12 September 2006 19:14, Andre Oppermann wrote: > > Mike Tancsa wrote: > > > At 12:43 PM 9/12/2006, Andre Oppermann wrote: > > >=20 > > >> TSO !=3D (vlan && promisc) > > >=20 > > > Sorry, the commonality I was referring to was VLAN hardware tagging a= nd=20 > > > how it must be enabled for TSO, but that breaks other things. See a = few=20 > > > messages ago > > >=20 > http://lists.freebsd.org/pipermail/freebsd-current/2006-September/065818.= html=20 > >=20 > > I'm sure we can find a workaround for that. >=20 > Well, you could have the em(4) driver manually handle TSO in software, wh= ich=20 > is what it does to workaround the VLAN tag problem. (It does VLAN=20 > encapsulation in the driver.) While VLAN insertion may be trivial,=20 > re-implementing TCP segmentation in the driver might be a good bit less= =20 > trivial to do. There's not going to be a simple easy workaround for this= =20 > hardware bug. :( I'm not sure it's worth worrying about with GbE hardware. Just disable TSO in promiscuous mode. Where TSO is going to really matter is 10GbE. No supporting TSO in some configurations with GbE doesn't seem like a big deal to me. -- Brooks --3V7upXqbjpZ4EhLz Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (FreeBSD) iD8DBQFFCCfNXY6L6fI4GtQRAsM/AJ9k7snMNGRUDq+0Ow0d2SyroGn7GQCgoGTZ DCElhWksL2WnykQFJeUfNnc= =3Ijl -----END PGP SIGNATURE----- --3V7upXqbjpZ4EhLz--
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