On Mon, 2017-01-23 at 13:46 -0800, Xiangning Yu wrote: > On Mon, Jan 23, 2017 at 12:56 PM, Cong Wang <xiyou.wangc...@gmail.com> wrote: > > On Mon, Jan 23, 2017 at 10:46 AM, Xiangning Yu <yuxiangn...@gmail.com> > > wrote: > >> Hi netdev folks, > >> > >> It looks like we call dev_forward_skb() in veth_xmit(), which calls > >> netif_rx() eventually. > >> > >> While netif_rx() will enqueue the skb to the CPU RX backlog before the > >> actual processing takes place. So, this actually means a TX skb has to > >> wait some un-related RX skbs to finish. And this will happen twice for > >> a single ping, because the veth device always works as a pair? > > > > For me it is more like for the completeness of network stack of each > > netns. The /proc net.core.netdev_max_backlog etc. are per netns, which > > means each netns, as an independent network stack, should respect it > > too. > > > > Since you care about latency, why not tune net.core.dev_weight for your > > own netns? > > I haven't tried that yet, thank you for the hint! Though normally one > of the veth device will be in the global namespace.
Well, per cpu backlog are not per net ns, but per cpu. So Cong suggestion is not going to work.
