On Tue, 2007-04-17 at 10:25 +0200, Sjoerd Simons wrote: > On Fri, Apr 06, 2007 at 12:38:34PM +0200, Michel Dänzer wrote: > > I noticed that all interfaces managed by NetworkManager seem to > > have an MTU of 576 bytes (the minimum). This seems to have a negative > > effect on download speed, or certainly not a positive one. As > > nm_system_get_mtu() in src/backends/NetworkManagerDebian.c returns 0, > > NetworkManager doesn't seem to set the MTU explicitly though, so I'm not > > sure where the default is coming from. I verified that hacking the above > > function to return 1500 results in interfaces managed by NetworkManager > > having an MTU of 1500, with a line like > > > > Apr 6 12:18:52 thor NetworkManager: <information>^ISetting MTU of > > interface 'sungem' to 1500 in syslog. > > I've personally never seen this behaviour. I've also got a powerbook with a > sungem network card and network-manager keeps it nicely at mtu 1500.
FWIW the same thing happens with the WiFi interface. I'm not ruling out a local configuration issue, but I can't seem to find anything related in /etc. Any suggestions what to look for? > When nm_system_get_mtu() returns 0, NM should just leave the mtu at the > default value.. Looking at the code, if the configured mtu == 0, the set_mtu > function just exits. So that all seems fine. Right. > So it seems we have ourselves a little mystery here :) I noticed your > running > kernel 2.6.21-rc5, could you try debian's 2.6.20-1 kernel to see if that > changes the behaviour ? I know that that works fine on my powerpc with a > sungem, so it allows us to easily see if the .21-rc kernel is doing strange > things. I only recently switched to running a self-built kernel for unrelated reasons. I previously used the standard Debian kernel for years and have been seeing this problem for a long time, possibly since I first started using network-manager. -- Earthling Michel Dänzer | http://tungstengraphics.com Libre software enthusiast | Debian, X and DRI developer
