Fri, Jan 22, 2016 at 08:11:22PM CET, ja...@redhat.com wrote: >The network core tries to keep track of dropped packets, but some packets >you wouldn't really call dropped, so much as intentionally ignored, under >certain circumstances. One such case is that of bonding and team device >slaves that are currently inactive. Their respective rx_handler functions >return RX_HANDLER_EXACT (the only places in the kernel that return that), >which ends up tracking into the network core's __netif_receive_skb_core() >function's drop path, with no pt_prev set. On a noisy network, this can >result in a very rapidly incrementing rx_dropped counter, not only on the >inactive slave(s), but also on the master device, such as the following: > >Inter-| Receive | Transmit > face |bytes packets errs drop fifo frame compressed multicast|bytes > packets errs drop fifo colls carrier compressed > p7p1: 14783346 140430 0 140428 0 0 0 2040 680 > 8 0 0 0 0 0 0 > p7p2: 14805198 140648 0 0 0 0 0 2034 0 > 0 0 0 0 0 0 0 > bond0: 53365248 532798 0 421160 0 0 0 115151 2040 > 24 0 0 0 0 0 0 > lo: 5420 54 0 0 0 0 0 0 5420 > 54 0 0 0 0 0 0 > p5p1: 19292195 196197 0 140368 0 0 0 56564 680 > 8 0 0 0 0 0 0 > p5p2: 19289707 196171 0 140364 0 0 0 56547 680 > 8 0 0 0 0 0 0 > em3: 20996626 158214 0 0 0 0 0 383 0 > 0 0 0 0 0 0 0 > em2: 14065122 138462 0 0 0 0 0 310 0 > 0 0 0 0 0 0 0 > em1: 14063162 138440 0 0 0 0 0 308 0 > 0 0 0 0 0 0 0 > em4: 21050830 158729 0 0 0 0 0 385 71662 > 469 0 0 0 0 0 0 > ib0: 0 0 0 0 0 0 0 0 0 > 0 0 0 0 0 0 0 > >In this scenario, p5p1, p5p2 and p7p1 are all inactive slaves in an >active-backup bond0, and you can see that all three have high drop counts, >with the master bond0 showing a tally of all three. > >I know that this was previously discussed some here: > > http://www.spinics.net/lists/netdev/msg226341.html > >It seems additional counters never came to fruition, but honestly, for >this particular case, I'm not even sure they're warranted, I'd be inclined >to say just silently drop these packets without incrementing a counter. At >least, that's probably what would make someone who has complained loudly >about this issue happy, as they have monitoring tools that are squaking >loudly at any increments to rx_dropped. > >CC: "David S. Miller" <da...@davemloft.net> >CC: Eric Dumazet <eduma...@google.com> >CC: Jiri Pirko <j...@mellanox.com> >CC: Daniel Borkmann <dan...@iogearbox.net> >CC: Tom Herbert <t...@herbertland.com> >CC: Jay Vosburgh <j.vosbu...@gmail.com> >CC: Veaceslav Falico <vfal...@gmail.com> >CC: Andy Gospodarek <go...@cumulusnetworks.com> >CC: netdev@vger.kernel.org >Signed-off-by: Jarod Wilson <ja...@redhat.com>
Acked-by: Jiri Pirko <j...@mellanox.com> I think this should be considered as a bug and go to -net.
