Re: [PATCH] VIOC: New Network Device Driver

Arnd Bergmann
2006-09-11T19:16:01Z

On Monday 11 September 2006 19:58, Misha Tomushev wrote:
> The descriptor clean-up does not contribute anything to the performance
> of the driver, it just replenishes the memory pools. It almost does not
> need interrupts. Why would we want to add more cycles to the receive
> logic, when driver is doing useful work for something that can run
> almost at any time?

It can run at almost any time, just not in the interrupt context,
where it needs to schedule the tx softirq first.

Also, the number of tx interrupts you get is a tradeoff between
causing overhead of calling the interrupt handler and stalling
sockets that are waiting for space to become free after transmission.
By using ->poll for it, you can avoid tx interrupts completely
most of the time and free skbs immediately when data comes in.