Date: Wed, 24 Jan 2007 17:02:35 -0800 (PST) From: Kelly Yancey <kbyanc@posi.net> To: Max Laier <max@love2party.net> Cc: freebsd-net@freebsd.org Subject: Re: slow writes on nfs with bge devices Message-ID: <20070124164949.P16327@gateway.posi.net> In-Reply-To: <200701212033.34914.max@love2party.net> References: <20070121155510.C23922@delplex.bde.org> <200701210809.27770.max@love2party.net> <20070121215054.C24780@delplex.bde.org> <200701212033.34914.max@love2party.net>
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On Sun, 21 Jan 2007, Max Laier wrote: > On Sunday 21 January 2007 13:25, Bruce Evans wrote: > > On Sun, 21 Jan 2007, Max Laier wrote: > > > On Sunday 21 January 2007 07:25, Bruce Evans wrote: > > >> nfs writes much less well with bge NICs than with other NICs (sk, > > >> fxp, > > > > > > Do you use hardware checksumming on the bge? There is an XXX in > > > bge_start_locked() that looks a bit suspicious to me. > > > > I use the default for that. Wouldn't checksum problems show up as > > errors somwhere? > > Did you look at the code in question? It is concerned with fragmented > packet chains (which NFS over UDP usually generated) and only commits to > sending them, if there are enough descriptors available at once. This > can easily explain burstyness. > > Can you just try to disable the delayed checksums via "ifconfig -txcsum"? > Should be an easy enough test. > I realize that Bruce has already identified the problem as being with the cabling, however I wanted to add a warning that disabling hardware checksums for bge cards is not a good idea. You can find my analysis of data corruption bugs caused by using bge cards without checksum offloading in the archives: http://lists.freebsd.org/pipermail/freebsd-net/2004-January/002530.html Kelly -- Kelly Yancey - kbyanc@posi.net | kelly@nttmcl.com
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