Doug Reynolds wrote:
On Sat, 18 Jan 2003 03:17:01 +0100 (CET), Marc Schneiders wrote:
[ ... ]
xl1: tx underrun, increasing tx start threshold to 180 bytes
xl1: transmission error: 90
xl1: tx underrun, increasing tx start threshold to 240 bytes
does that mean it is increasing or decreasing?
Good ethernet cards can attempt to transmit a packet before the local system has actually written all of the data to them.

If the local system fails to produce the data quickly enough, though, the card experiences a buffer underflow...which means about the same as it does when you burn a CD; it has to abort and resend the packet. The driver is smart enough to notice this, and will try to compensate by buffering more data before sending the packet out (ie, the "start threshold"), so that the machine has more time to finish generating the packet.

This is also a situation where device polling might be quite helpful.


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