[vortex] Packet-loss and/or interface blocking on 3c905C-TX cards

[Andrew Morton]

Gerrit Einhoff wrote:
> 
> ...
> As you can see we
> experienced packet losses up to 80%, but only for the packet-sizes from 112
> bytes to 354 bytes. These results are reliable reproducible. With
> packet-sizes of 354 bytes, we have losses of 80%, with 355 bytes no losses at
> all! Apparently the packets are lost at the sending side, because the program
> finishes five times faster with 354 bytes packets than with 355 bytes packets.

I'm not 100% sure about this, but I suspect it's a UDP
thing.  If an application is squirting UDP packets
out faster than the interface can sustain, the kernel
just drops them on the floor when the socket send buffer
fills up.