On Wednesday 24 March 2010 03:20:18 Zhu Yi wrote: > On Wed, 2010-03-24 at 09:59 +0800, Johannes Berg wrote: > > On Tue, 2010-03-23 at 21:51 +0100, Christian Lamparter wrote: > > > While ar9170's USB transport packet size is currently set to 8KiB, > > > the PHY is capable of receiving AMPDUs with up to 64KiB. > > > Such a large frame will be split over several rx URBs and > > > exceed the previously allocated space for rx stream reconstruction. > > > > > > This patch increases the buffer size to 64KiB which is > > > in fact the phy & rx stream designed size limit. > > > > That's a pretty high order allocation, you may want to paged allocation > > -- you'll end up doing a order 5 allocation here! > Yup, order-5 given the struct skb_shared_info overhead in __alloc_skb(). > If the URBs are split over, you probably don't need to allocate such a > big chunk of memory in one go. I know, I know, but unfortunately I do need a continuous address space. The reason is that usually one URB can have up to 5 data frames (each with ~1600 Octets). That's why the driver memcpys everything from the rxstream skbs into newly allocated ones for each individual frame. (The reconstruction simply adds another memcpy to a temporary buffer, until we have everything...). as far as I can tell, there's only one other options: * mix vmalloc with paged skbs API ;-) This looks kind of funny. The API abuse is highly questionable and probably not something for "stable". * early drop, if len > 8KiB This has the downside that we lose the data and the rx stream state. (E.g.: signal quality & phy data, mac error codes, the lot...) * something I don't know? please tell me about it! > You just need to connect them into a paged skb later before pushing to mac80211. > BTW, I've moved the skb_linearize() from iwlwifi to mac80211. Will submit the patches today. AFAIK Atheros resolved this issue with AR9271. At least that's what I heard from Luis about the _new_ scatter/gather IO implementation. Regards, Chr -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
