[vortex] Recomended module options Vortex card?

[Andrew Morton]

Stefan Srdic wrote:
> 
> I used some of the module options to force the device into full duplex
> mode. I'm a little interrested in the rx_copybreak and the
> max_interrupt_work settings. Does the rx_copybreak affect the number of
> packets or frames buffered by the device? If so, what is the recomended
> value under normal operations? Also, what is the recomemded
> max_interrupt_work setting? Would a lower setting produce smoother
> processing of data, or, would a larger number do the same?
> 

The driver receives packets into full-sized buffers - 1560 bytes.
When a packet comes in the driver needs to make a decision.  Does
it use the whole 1560 bytes for this packet, or does it allocate
a smaller buffer on-the-fly and copy the data into it?

That's what rx_copybreak is for.  If the newly arrived packet is smaller
than this then a new buffer is allocated and the data is copied into it.

If you have a lot of memory then you can probably afford to use a full-sized
buffer on even tiny packets.  So setting rx_copybreak to something tiny
may provide some performance benefit.  But I doubt it'd be observable.

max_interrupt_work won't affect performance.  It's basically a counter
which tells the driver when to give up processing packets in a single
interrupt.  If the default value is exceeded then either you're doing
something extraordinary or something is broken.