On Mon, Feb 03, 2003 at 10:48:37PM +0000, David Laight wrote:

 > That cycle is a waste of time, you might as well look to see if
 > there is an rx data (etc), the driver will have to look there as well.
 > For ring based drivers the ring structure itself can be polled.
 > This will be much cheaper than an access to the chip.

Yah, exactly.

 > I got a massive benefit on one ethernet driver by almost never
 > taking the 'end of transmit' interrupt.  You can 'reap' the
 > transmit descriptors during tx setup.  Only packet blasting needs it
 > (oh and when the sending code isn't goimg to do anything else until
 > you free it's buffer, On that system only NFS did that to us.)

There are other ways you can mitigate ... like, Tx interrupt when the Tx
descriptors are 1/2-used, or something, and bound it by just checking
every second.

-- 
        -- Jason R. Thorpe <thorpej@wasabisystems.com>