On Mon, 16 Nov 2015 17:48:35 -0600 Matt Laswell <laswell at infiniteio.com> wrote:
> Hey Folks, > > I sent this to the users email list, but I'm not sure how many people are > actively reading that list at this point. I'm dealing with a situation in > which my application loses the ability to transmit packets out of a port > during times of moderate stress. I'd love to hear suggestions for how to > approach this problem, as I'm a bit at a loss at the moment. > > Specifically, I'm using DPDK 1.6r2 running on Ubuntu 14.04LTS on Haswell > processors. I'm using the 82599 controller, configured to spread packets > across multiple queues. Each queue is accessed by a different lcore in my > application; there is therefore concurrent access to the controller, but > not to any of the queues. We're binding the ports to the igb_uio driver. > The symptoms I see are these: > > > - All transmit out of a particular port stops > - rte_eth_tx_burst() indicates that it is sending all of the packets > that I give to it > - rte_eth_stats_get() gives me stats indicating that no packets are > being sent on the affected port. Also, no tx errors, and no pause frames > sent or received (opackets = 0, obytes = 0, oerrors = 0, etc.) > - All other ports continue to work normally > - The affected port continues to receive packets without problems; only > TX is affected > - Resetting the port via rte_eth_dev_stop() and rte_eth_dev_start() > restores things and packets can flow again > - The problem is replicable on multiple devices, and doesn't follow one > particular port > > I've tried calling rte_mbuf_sanity_check() on all packets before sending > them. I've also instrumented my code to look for packets that have already > been sent or freed, as well as cycles in chained packets being sent. I > also put a lock around all accesses to rte_eth* calls to synchronize access > to the NIC. Given some recent discussion here, I also tried changing the > TX RS threshold from 0 to 32, 16, and 1. None of these strategies proved > effective. > > Like I said at the top, I'm a little at a loss at this point. If you were > dealing with this set of symptoms, how would you proceed? > I remember some issues with old DPDK 1.6 with some of the prefetch thresholds on 82599. You would be better off going to a later DPDK version.