Hey, * Daniel Melameth <dan...@melameth.com> [2015-01-23 22:38]: > I noticed the following when downloading a large file: > > queue tcp_ack parent root on fxp0 bandwidth 2M qlimit 50 > [ pkts: 289461 bytes: 15631434 dropped pkts: 16 bytes: 864 ] > [ qlength: 0/ 50 ] > [ measured: 3660.9 packets/s, 1.58Mb/s ] > > While the number of dropped packets is very small and probably > insignificant, I would have expected zero dropped packets as little > else is competing for the ~12Mbps that's available in the parent > queue/circuit. I thought this might be related to qlength, but since > this is, apparently, zero during the time of the download I'm not > certain what would be causing this. What might I be missing here and > how do I resolve (I don't want to set a min here if it can be > avoided).
First, get over the misconception that dropped packets are bad. The opposite is almost true. With tcp, dropping a packet signals the sender to slow down. You're seeing the few dropped packets because your queue at some time hit its limits. Comparing an ever-growing counter (drops) with an averaged, somewhat current rate can be very misleading. > FWIW, net.inet.ip.ifq.drops=0. 100% unrelated. -- Henning Brauer, h...@bsws.de, henn...@openbsd.org BS Web Services GmbH, http://bsws.de, Full-Service ISP Secure Hosting, Mail and DNS. Virtual & Dedicated Servers, Root to Fully Managed Henning Brauer Consulting, http://henningbrauer.com/
