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

[Felix Fietkau <nbd@openwrt.org>]

On 2011-01-24 11:33 PM, Ben Greear wrote:
> Some time back, I posted a patch to implement rx-copybreak for
> ath9k.  There were some other alternative patches that implemented
> paged skbs.
> 
> My patch had at least one real problem in that it needs to handle
> arbitrary busses, not just pci.  Seems that wouldn't be too hard
> to implement, but I haven't bothered to date.  It has been stable
> for several weeks of testing on various pci-e and pci ath9k NICs.
> 
> There was also a worry that for more normal use cases a paged skb
> approach might be preferred over the skb-copybreak approach.
> 
> I, and a few others, liked pure copybreak because it might work
> around DMA start/stop issues in ath9k by ensuring that the hardware
> never scribbles on packets handed up the stack.  To me, this is
> more important than performance, but then again, I have plenty of
> CPU resources available on my systems.
> 
> 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?
> 
> Or should someone fix up the paged skb approach?
I think finishing Jouni's patch and using that instead of the copybreak
changes is the way to go, as it fixes the order-1 allocations without
unnecessary data copying.

- Felix