On Tue, Jul 07, 2009 at 11:47:38AM -0700, Rick Jones wrote: > Anton Vorontsov wrote: > >We can reclaim transmitted skbs to use in the receive path, so-called > >skb recycling support. > > > >Also reorder ucc_geth_poll() steps, so that we'll clean tx ring firstly, > >thus maybe reclaim some skbs for rx. > > Admittedly, all the world is not TCP, but a big chunk is, so are you > likely to have reference counts go to zero on the tx queue for > anything other than small standalone TCP ACK segments?
That's a generic question wrt skb recycling, right? Whether we can always recycle transmitted skbs. No, sometimes (or mostly) we can't. Initially, I was quite puzzled by this support... looking at how gianfar driver works (it has the same support as of 0fd56bb5be6455d0), I noticed that skb_recycle_check() always returns 0, and so we don't recycle the skbs. Though, things change when the kernel starts packets forwarding, *then* skb recycling path actually triggers. Lennert (skb recycling author) hints us that the gain is indeed in forwarding/routing workload: http://kerneltrap.org/mailarchive/linux-netdev/2008/9/28/3433514 Hope I understood everything correctly. :-) Thanks! -- Anton Vorontsov email: cbouatmai...@gmail.com irc://irc.freenode.net/bd2 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
