On Wed, 30 Dec 2015 09:52:49 -0800 John Fastabend <john.fastab...@gmail.com> wrote:
> The net sched infrastructure has a gso ptr that points to skb structs > that have failed to be enqueued by the device driver. What about fixing up the naming "gso" to something else like "requeue", in the process (or by an pre-patch) ? > This can happen when multiple cores try to push a skb onto the same > underlying hardware queue resulting in lock contention. This case is > handled by a cpu collision handler handle_dev_cpu_collision(). Another > case occurs when the stack overruns the drivers low level tx queues > capacity. Ideally these should be a rare occurrence in a well-tuned > system but they do happen. > > To handle this in the lockless case use a per cpu gso field to park > the skb until the conflict can be resolved. Note at this point the > skb has already been popped off the qdisc so it has to be handled > by the infrastructure. I generally like this idea of resolving this per cpu. (I stalled here, on the requeue issue, last time I implemented a lockless qdisc approach). -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
