Subject: Why is NMBCLUSTERS too low by default?
To: None <>
From: Janne Snabb <>
List: tech-net
Date: 03/24/2002 01:28:41
On Thu, 21 Mar 2002, Piotr Stolc wrote:

> I would try increasing NMBCLUSTERS value. 2048 is not so very high value...

Is there a reason why the value of NMBCLUSTERS is very low by default?
To me it seems that the default value is too low for most purposes
(for a machine which has ethernet connectivity).

Whenever I install a new NetBSD system and accidentally forget to compile
a new kernel with higher NMBCLUSTERS defined (or am just too lazy), the
machine will always eventually start hitting the mbuf limit. And then
the machine needs to be rebooted just to increase the value because it
is not even a sysctl...

If there is a reason not to increase the default to a reasonable value
which suits most purposes (lets say 2048), I think there should be at
least a commented reasonable definition with a description in the GENERIC
kernel configuration file so that people would be spotting and enabling
it when they compile their kernels. I feel that this is quite a FAQ on
NetBSD lists...

Janne Snabb / SSH Communications Security Corp