3c59x: recurring transmit errors

Kurt Fitzner kfitzner@nexus.v-wave.com
Tue Jul 28 14:51:27 1998

On 28-Jul-98 Ben Liblit wrote:

> Several times a day, I seem to lose all network connectivity through
> this interface.  This is an NFS-intensive environment, so NFS timeouts
> are generally the first symptom.  The driver reports transmit errors
> with one of three different status registers:

I had the exact same problem.  I have a 3c590, though, on a small (3 machines)
10Mbit network.  I had been enabling DMA on my card (which the driver docs
say is 'experimental' on this card).  This worked just fine for a long time,
then I started getting the errors when I moved from kernel 2.0.33 to 2.0.34. 
I tried using my old 2.0.33 drivers, I tried everything I could think of. 
So, in the end, I turned off DMA transfers.

The driver says that enabling DMA isn't a good idea for performance reasons,
citing the 'performance hit' of an 'extra interrupt' as the reason.  I don't
understand this.  Surely my CPU can service one interrupt much faster than it
can loop through reading and writing 1500 bytes off my card.  If someone can
explain this, or the transmit error problem, I'd appreciate it.

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