vr speed issues

Charles Sprickman spork at bway.net
Tue Nov 28 23:50:00 PST 2006

Hi all,

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):




Charles Sprickman
Bway.net - New York's Best Internet - www.bway.net
spork at bway.net - 212.655.9344

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