Re: abnormal overruns?

From: marky
Date: Sun May 25 2008 - 21:33:25 EST


On Sat, 2008-05-24 at 21:10 -0400, Bill Fink wrote:
> On Fri, 23 May 2008, marky wrote:
>
> > Upon checking the output from ifconfig, I've noticed one of my ethernet
> > cards has an unusually high overrun count:
> >
> > eth0
> > RX packets:893306935 errors:5 dropped:0 overruns:29316 frame:5
> >
> > Coincidentally, eth2 on the same box has
> > RX packets:832545758 errors:0 dropped:0 overruns:5116 frame:0
> > TX packets:873232422 errors:0 dropped:0 overruns:152 carrier:0
> >
> > eth0 is our lan interface and eth2 is our interface that corresponds
> > with the cable modem. I believe eth0 is a 3com NIC and eth2 is an
> > eepro100 card.
> >
> > The box itself acts as a router for about 6 other machines in our lan
> > running kernel 2.6.
> >
> > Testing this when transferring a 30 MB file to the router itself yielded
> > an increase in overruns. This seems abnormal as 29k overruns seems quite
> > high. The computer itself is somewhat overkill for router purposes so it
> > makes me wonder, is this an error in the driver or is there a bottleneck
> > somewhere else?
>
> Do you have flow control enabled on eth0 and eth2? You can check
> with "ethtool -a ethX".
>
> Also check the settings of /proc/sys/net/core/netdev_max_backlog
> (for the receive side) and the txqueuelen from ifconfig (for the
> transmit side).
>
> And "ethtool -S ethX" will give more detailed device statistics if
> the driver supports it. You can then check the driver specific
> documentation (if available) to get more detailed info on any
> relevant driver error counters.
>
> -Bill

ethtool -a eth0 and ethtool -a eth2 both give me
Cannot get device pause settings: Operation not supported

$ cat /proc/sys/net/core/netdev_max_backlog
1000

eth0's txqueuelen
collisions:0 txqueuelen:1000

and eth2's txqueuelen
collisions:0 txqueuelen:1000

Checking eth0's statistics only shows 43577 rx_bad_ssd's where as eth2
won't give me any statistics whatsoever as none appear to be available.

Having trouble finding 3c59x documentation unfortunately. :\

-Mark

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