Hey Stephen, Thanks a lot; that's really useful information. Unfortunately, I'm at a stage in our release cycle where upgrading to a new version of DPDK isn't feasible. Any chance you (or others reading this) has a pointer to the relevant changes? While I can't afford to upgrade DPDK entirely, backporting targeted fixes is more doable.
Again, thanks. - Matt On Mon, Nov 16, 2015 at 6:12 PM, Stephen Hemminger < stephen at networkplumber.org> wrote: > 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. >