On 08/19/2015 08:20 PM, Eric Dumazet wrote: > On Wed, 2015-08-19 at 17:00 +0000, Grumbach, Emmanuel wrote: >> >> On 08/19/2015 07:08 PM, Eric Dumazet wrote: >>> On Wed, 2015-08-19 at 15:07 +0000, Grumbach, Emmanuel wrote: >>> >>>> I'll look at it. >>>> I was almost starting to implement that but then I thought with another >>>> (good?) reason to use LSO. LSO gives me the guarantee that the packet is >>>> directed to one peer, which might not be the case with xmit_more since >>>> we have one Qdisc for several clients in case we are in AP mode. >>>> Building an A-MSDU for several clients is not possible, at least not for >>>> several client in the L2 (different MAC addresses). >>>> LSO avoids this problem completely. >>> >>> Then, simply calling skb_gso_segment() from the driver might be enough, >>> and less work for you. >>> >>> This would even support TSO on IPv6 >>> >> >> Well... I did take care of IPv6. > > net/core/tso.c does not yet handle IPv6 > Yeah - I can see that now. I can teach him - that's not a big deal. The bigger problem is that net/core/tso.c doesn't do what I really need: it does only a small portion. Since I need to add one frag to several skbs, I need to refcount the frags' page. net/core/tso.c hides the page from me. I can try to use tso_build_hdr but it will copy the entire header where I need only SNAP / IP / TCP (and not 802.11). I am getting the feeling that net/core/tso.c is close to what I need, but not close enough to be usable without making changes that would make the implementation too complicated and changing net/core/tso.c in a way that would be much less readable for other users. I know that our device is quite "unique" in the sense that most other vendors do all the header twiddling in hardware. We unfortunately don't. The A-MSDU's format is also somewhat unusual: <802.11 HDR> <ETH><SNAP><IP><TCP><PAYLOAD><PAD (variable length) <ETH><SNAP><IP><TCP><PAYLOAD><PAD (variable length) <ETH><SNAP><IP><TCP><PAYLOAD><PAD (variable length) etc... So I feel that making net/core/tso.c more complicated just because of our craziness seems an overkill to me. I'll try a bit harder to see how I can use net/core/tso.c, but I have to say I am pessimistic. -- 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
