On Tue, 22 Oct 2002, Ben Greear wrote:
> Actually, with the changes the way they are, if you have a backlog value
> of 300, and the first NAPI driver reads 300 packets, then all the rest of the
> NAPI drivers will just throw away packets because the max-backlog has
> already been hit (if I understand things correctly).
The 300 is shared amongst all the drivers which have something on their
rx DMA. This is done on a roundrobin fashion.
Also all the drivers which are non-napi are given the same quota.
> If we make the backlog big enough to handle a large burst of incomming
> traffic w/out dropping them, then the first NAPI driver can hog a very
> large amount of CPU because its budget is now huge. The rest of
> the devices in the poll loop will not be serviced in time, and will
> drop packets (I saw this when testing out the 4-port tulip driver with
> the NAPI patch).
I think you misunderstood. Look at the dev->weight.