Date: Wed, 19 Oct 2011 20:12:30 +0100 From: Ben Hutchings <bhutchings@solarflare.com> To: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net> Cc: freebsd-net@freebsd.org, Andre Oppermann <andre@freebsd.org> Subject: Re: TSO broken with jumbo MTU Message-ID: <1319051550.2829.34.camel@bwh-desktop> In-Reply-To: <68546593-B3E1-44D8-B512-4FD99B90D989@lists.zabbadoz.net> References: <1317309906.2743.9.camel@bwh-desktop> <1318865394.2784.4.camel@bwh-desktop> <4E9C534D.4090405@freebsd.org> <1318894136.2784.76.camel@bwh-desktop> <68546593-B3E1-44D8-B512-4FD99B90D989@lists.zabbadoz.net>
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On Mon, 2011-10-17 at 23:59 +0000, Bjoern A. Zeeb wrote: > On 17. Oct 2011, at 23:28 , Ben Hutchings wrote: > > > On Mon, 2011-10-17 at 18:09 +0200, Andre Oppermann wrote: > >> On 17.10.2011 17:29, Ben Hutchings wrote: > >>> This is the fix/workaround I used: > >> > >> Thanks for the fix. I'll review it and put it into FreeBSD maybe in > >> a slightly different form. > > > > Which one? One is tested but maybe not right; the other looks right but > > is not tested! > > and here's the real question -- was it always broken or did a commit during > the last years introduce the problem? t_maxopd > t_maxseg has always been possible since t_maxopd was added: http://svnweb.freebsd.org/base?view=revision&revision=6247 http://svnweb.freebsd.org/base?view=revision&revision=6283 The commit introducing TSO support was: http://svnweb.freebsd.org/base?view=revision&revision=162110 and that already had the problem that TSO may be selected for an mbuf that only requires one segment if t_maxopd > t_maxseg. The assertion that failed was added in: http://svnweb.freebsd.org/base?view=revision&revision=211317 As to which of these is the real bug, I cannot say. The commit message for the last change hopefully provides a clue for those more familiar with this TCP implementation. Ben. -- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.
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