Re: RFC: new ifnet MP-scalable sending interface

[Joerg Sonnenberger <joerg%bec.de@localhost>]

On Fri, Apr 22, 2016 at 11:09:24AM +0900, Kengo NAKAHARA wrote:
> So, I want to introduce new MP-scalable ifnet interface which doesn't
> use if_snd queue and directly pass mbuf to lower layers. The interface
> is called if_transmit() and the prototype is the following:
>     int (*if_transmit)(struct ifnet *, struct mbuf *);

Let me try to expand that a bit and you comment on whether it actually
reflects your intention.

The old interface queueing implementation is based on assumption
that restarting transmits after the in-device queue is cheaper than
continued requeueing from the network stack. The new interface provides
a hook for processing each outgoing packet individually. It can provide
the old interface via a generic glue implementation, but it also allows
a device more granular control. Most noticably, it can be used to avoid
ever getting TXEOF interrupts while the device is actively being used.

Joerg