That kinda sounds like an interrupt issue, in which case I suggest turning polling on for both interfaces. ifconfig <blah> polling ought to do it. If that fixes the problem, then it is definitely interrupt-related.
-Matt On Mon, Oct 17, 2016 at 12:52 PM, Richard Nyberg <[email protected]> wrote: > Thanks again for your suggestions. > > Actually it's much stranger than I thought. While troubleshooting I > had this configuration: > > df (em0) -> switch <- desktop > > No other devices or network interfaces were connected. In this > configuration there was no problem at all with latency. I then plugged > in the cable with internet acces like below: > > internet <- (re0) df (em0) -> switch <- desktop > > In this configuration the latency problems immediately showed. The fun > thing is that when I unplugged the re0 interface again the em0 > interface stopped responding at all, until I put the cable back to > re0. Then em0 was back but with latency problems. > > Another data point is that while I downloaded a large file at speed > from the internet via df to my desktop in the above configuration and > pinged from the desktop to df at the same time, the latency problems > were gone. Until the download was finished and they started again. > > -Richard > > On 16 October 2016 at 19:14, Matthew Dillon <[email protected]> wrote: > > Look for a packet loop on the interface. Use tcpdump on the interface to > > see if there are excess packets being generated from somewhere. There > are > > numerous things that can blow up a LAN. The most common being that a > switch > > port is wired to loop back into the LAN. > > > > -Matt > > > > On Sun, Oct 16, 2016 at 9:17 AM, Justin Sherrill < > [email protected]> > > wrote: > >> > >> On Sun, Oct 16, 2016 at 11:49 AM, Richard Nyberg <[email protected] > > > >> wrote: > >> > Thanks! > >> > > >> > Here are some more datapoints. > >> > >> I think the only constant at this point is the internal interface on > >> the DragonFly system. If you hook the em0 interface that's currently > >> internal on the DragonFly machine up to your Internet link (i.e. > >> reverse which interface is internal or external), does it still > >> perform badly? > >> > >> If it doesn't work well, then that interface is bad. I'd be > >> surprised, cause I've seen network ports go bad very rarely, but it's > >> possible. Plus, I don't have any other ideas. > > > > >
