From: Eric Dumazet <eric.duma...@gmail.com> Date: Thu, 30 Apr 2015 09:40:40 -0700
> From: Eric Dumazet <eduma...@google.com> > > Under presence of TSO/GSO/GRO packets, codel at low rates can be quite > useless. In following example, not a single packet was ever dropped, > while average delay in codel queue is ~100 ms ! > > qdisc codel 0: parent 1:12 limit 16000p target 5.0ms interval 100.0ms > Sent 134376498 bytes 88797 pkt (dropped 0, overlimits 0 requeues 0) > backlog 13626b 3p requeues 0 > count 0 lastcount 0 ldelay 96.9ms drop_next 0us > maxpacket 9084 ecn_mark 0 drop_overlimit 0 > > This comes from a confusion of what should be the minimal backlog. It is > pretty clear it is not 64KB or whatever max GSO packet ever reached the > qdisc. > > codel intent was to use MTU of the device. > > After the fix, we finally drop some packets, and rtt/cwnd of my single > TCP flow are meeting our expectations. > > qdisc codel 0: parent 1:12 limit 16000p target 5.0ms interval 100.0ms > Sent 102798497 bytes 67912 pkt (dropped 1365, overlimits 0 requeues 0) > backlog 6056b 3p requeues 0 > count 1 lastcount 1 ldelay 36.3ms drop_next 0us > maxpacket 10598 ecn_mark 0 drop_overlimit 0 > > Signed-off-by: Eric Dumazet <eduma...@google.com> Looks good, applied, thanks Eric. -- 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
