[ath9k-devel] Paged SKBs v/s copybreak.

[Jouni Malinen <jouni.malinen@atheros.com>]

On Mon, 2011-01-24 at 14:33 -0800, Ben Greear wrote:

> So, I am hoping for some guidance from the core ath9k folks.  Should
> I attempt to fix my copybreak patch for non pci busses and re-post
> it?

My preference would be to use multiple RX buffers to receive long frames
(chain RX descriptors with rs_more). I sent a preliminary patch for
doing that. Unfortunately, I have not had time to complete this and
probably in the near future. However, if someone has time available, it
should be simple to get the initial version into suitable condition
(just add support for the EDMA case where there may extra meta data in
the beginning of the first RX buffer). That should already be enough to
get the patch in and handle skb taking more than a page allocation
issue. As the next step, mac80211 could be optimized to be able to
handle A-MSDU RX without having to re-allocate and copy the received
long buffers.

The main benefit of this approach is that only the really long frames
(A-MSDU RX) would suffer from the need to re-allocate and copy and even
that A-MSDU RX case can be optimized by extending mac80211. In addition,
this should make it easy to take larger A-MSDU size limit into use
without extra cost for throughput reasons in the future.

- Jouni