Date: Wed, 2 Jul 2014 22:09:13 -0400 (EDT) From: Rick Macklem <rmacklem@uoguelph.ca> To: "Russell L. Carter" <rcarter@pinyon.org> Cc: freebsd-net@freebsd.org Subject: Re: NFS client READ performance on -current Message-ID: <509953671.6648047.1404353353654.JavaMail.root@uoguelph.ca> In-Reply-To: <53B4A605.8000604@pinyon.org>
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Russell L. Carter wrote: > > > On 07/02/14 17:17, Michael Sierchio wrote: > > sysctl net.inet.tcp.tso=0 > > Woot! 2.7MB/s -> 76MB/s > > Is this a FAQ somewhere? I spent a long time looking > today and didn't find it (I do recall seeing a mention > of TSO but not seeing how to do it or that it fixed > the problem) > Unfortunately, this isn't good news for me. I had thought the worst of the TSO related problems had been resolved in head. The one I knew about was a case where a read/write just under 64K would result in a TSO segment (including ethernet header) just over 64K (which can't fit in 32 mbuf clusters, while 32 is the limit for transmit segments for some TSO enabled interfaces). I think this is fixed in head by r264630, which reduces the maximum tso segment length by a small amount. Admittedly, if the network interface is limited to less than 35 transmit segments and does not use m_defrag() to compact the TSO segment into 32mbuf clusters, it would still be broken. The m_defrag() calls will result in overhead, but I don't think they would cause that much effect. Could you please post the dmesg stuff for the network interface, so I can tell what driver is being used? I'll take a look at it, in case it needs to be changed to use m_defrag(). Thanks for letting us know this fixed the problem, rick > On the second suggestion: > > root@feyerabend> sysctl -a | grep dev.em | grep enable_ > root@feyerabend> > > No problem, though. 76MB/s is A-OK. > > Thanks! I'm very happy now. > > Russell > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to > "freebsd-net-unsubscribe@freebsd.org" >
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