vr speed issues
spork at bway.net
Tue Nov 28 23:50:00 PST 2006
I spent some time trying to track down slow tcp performance on a small
office switched 100 LAN. We just put in a number of whitebox PCs running
FreeBSD 6.1-p2/PC-BSD 1.2 that all have onboard Via Rhine 10/100 ethernet
controllers. Performace with scp was around 200KB/s, ftp wavered between
300-500KB/s. This did not appear to be a duplex mismatch - unmanaged
switch showed them all at 100/Full, put some other hosts on the same
ports/cabling and got near wire speed. I took the cabling out of the
equation, the switch, no improvement. The only thing that got me decent
performance was putting two hosts back to back with an xover cable.
I eventually realized that the only hosts with any speed issues in the
office were these boxes with the Via ethernet. Putting an equally cheap
DLink (RealTek/rl) in one of them gave me much better performance.
At another site, I was dealing with a new intranet server running FreeBSD
6.2-PRE (11/16) on a decent Asus board. This also has an onboard Via
Rhine ethernet controller. While pulling some files over from the box it
was replacing, I noticed that I was getting only a few hundred KB/s on
this box. Before putting it into production, I grabbed a cheap Intel
10/100 card and put that in. Problem solved.
So it seems to me like perhaps there's an issue with the vr driver. I
noticed it does have some quirks mentioned in the manpage, and I don't see
too many changes to the driver in the last year or so.
Is there any information I can supply to help debug this? I've got a
bunch of these machines around. I can get a tcpdump from both ends during
an ftp transfer, and the boxes are mine to toy with after hours.
I've posted a dmesg from both boxes (PC-BSD and 6.2-PRE):
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spork at bway.net - 212.655.9344
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