On Fri, 2009-11-27 at 10:52 +0800, Zhu Yi wrote: > > Also -- you lost the extra TX headroom which I think mac80211 as an AP > > requires since it could forward these frames? Or does that not happen? > > Not sure right now why that was there to start with. > > Yes, I'd like to hear more feedback on this. I think it's a trade off > between performance optimization and clean interface. As we already use > dev_alloc_skb to reserve 32 bytes headroom, it should be enough for most > of the current drivers. Is it? I don't think so. Many drivers go up beyond that as far as I know. Then some do different things like putting it in a different DMA block. > While for those drivers really need a bigger > extra headroom and support Rx aggregation, this probably means > ieee80211_skb_resize. But the resize should always happen for every > packet from the IP stack, right? No, davem and I optimised that away a long time ago via using netdev->needed_headroom and netdev->needed_tailroom. It even works for bridges and their slave devices, iirc. johannes
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