Subject: System slowly dying under heavy UDP load.
To: None <,>
From: Lars-Johan Liman <>
List: current-users
Date: 06/25/2002 19:07:31
I have a DNS service that takes pretty heavy load, some 1000-2000 UDP
queries per second.

I've tried to use PC servers with various versions of NetBSD
(1.5.3_RC2, 1.5ZC), and two pretty different versions of hardware
(different motherboards, different NICs (Intel Pro100 fxp and Netgear

They seem to run fine for a few hours, but after a while the become
less and less interested in talking with the rest of the
world. Typically the first step is that remote login starts to hang,
but DNS continues to work. Later on DNS stops to work, and your left
with the not too exciting "ping" service ;-), and eventually the go
totally catatonic, and power cycle is the only cure. CTRL-ALT-ESC
doesn't work then, the console looks as an image of a completely happy
system, it's just that nothing what so ever happens after any known
combination of keystrokes, including several well known "vulcan death
grips". ;-)

It seems to work better under 1.5.2, although I don't say that with
100 % conviction.

Has anyone else seen this in late versions of NetBSD?

Any chance at all that it can be related to the net.inet.tcp.cwm
stuff? (Probably not, this is UDP.)

Any hints on how to debug this?

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