Date: Tue, 23 Dec 1997 15:36:33 -0600 From: Dan Nelson <dnelson@emsphone.com> To: Sean Shilton <sshilton@ascend.com> Cc: freebsd-questions@freebsd.org Subject: Re: 3com 3c905 TX Message-ID: <19971223153633.27664@emsphone.com> In-Reply-To: <34A01A21.5ED0@ascend.com>; from "Sean Shilton" on Tue Dec 23 15:08:01 GMT 1997 References: <34A01A21.5ED0@ascend.com>
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In the last episode (Dec 23), Sean Shilton said: > I have a dell pentium II 266 with a 3com 3c905 TX 10/100BT network > card. I am running nfs mounts from a Sun Ultra Sparc 2 (running > solaris 2.5.1) When i have the freebsd machine conencted to a > 10/100bt switch (bay networks 350t) the freebsd machine will hang > (only ctrl+alt+del or a hard boot will reset the box) when i try to > do an ls on my home directory which has +100 indavidual listings. > When the freebsd machine is plugged into a regular 10bt hub, i have > no problems with any of the nfs mounts, and doing a ls on my home > directory works fine. The device Freebsd is using for the nic card > is vx0. I was wondering if there was either an updated driver for > that nic card, or if there was a way to increase buffering with NFs > so that the machine will not hang when i use the 100bt connection. (boilerplate 3c905 response follows) The 3c905 is just a low-quality card. Check out http://www.3com.com/0files/products/dsheets/400243a.html, and look at the "Transmit/Receive Buffer Memory" section. It has an 8k buffer, partitioned by default at 4k xmit, 4k recv. At 100Mbps, the card will never be able to receive a full 8k NFS packet without dropping a fragment. NFS retries by resending the entire 8k packet, and that's where your deadlocks are coming from. At 10Mbps, the card is able to process an entire 8K packet, so your deadlock disappears. You can try mounting the NFS volumes with -r1024,-w1024,-I512, which will force 1K NFS packets. Interestingly enough, the ISA version (the non-XL version) has a 64k buffer, but the PCI version has the 8k buffer.. You might want to try another network card, if you can. The DEC 21140-based cards are supposed to be good, and the Intel EtherExpress Pro 10/100B is also a good card. I can sustain 5MB/s reads over NFS from a P6/200 server to a P133 client with EE/100B cards in both machines. -Dan Nelson dnelson@emsphone.com
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