On Fri, 22 Dec 2017 18:11:39 +0100, Jesper Dangaard Brouer wrote:

+struct xdp_rxq_info {
+	struct net_device *dev;
+	u32 queue_index;
+	u32 reg_state;
+} ____cacheline_aligned; /* perf critical, avoid false-sharing */

I'm assuming this is cacheline_aligned, because of some stuff you will
add here in the future for the completion path?  (The comment could
mention that this data is read-mostly.)  Drivers are likely to already
have a read-mostly (or unused-mostly) section of the rx ring structure.
Would it be possible to define this in a way that would allow people
who carefully lay out their data path structures to save cache space?