Subject: Re: WARNING: mclpool limit reached; increase NMBCLUSTERS
To: Mason Loring Bliss <>
From: Manuel Bouyer <>
List: current-users
Date: 05/19/1999 19:56:56
On May 19, Mason Loring Bliss wrote
> Hm. Okay. I'll bounce it up again.
> Is there anywhere where I can read on a fairly high level how exactly
> NMBCLUSTERS are used? I'd love to know why I'm changing numbers, rather
> than simply worshipping the box that drops from the sky...

NMBCLUSTERS is the maximum number of mbuf clusters. They are used to
store datas in various network protocols (and also for Unix sockets, and
maybe fifos, I don't know how the last one works :). A small packet can be
stored in a simple mbuf, bot for larger packets one or more mbuf clusters
will be associated to the mbuf to store the data.

netstat -m will show you how much mbufs and how much data you system
> > But you may need to increase NKMEMCLUSTERS as well.
> Is there a desired relationship betweem these two values? By default
> NKMEMCLUSTERS appears to be 4096 on three different machines I've got
> available right now.

Well if you increase NMBCLUSTERS, this allows the kernel to allocate
more memory for itself. The vm system may need more resources to manages it.
It'd say, which the memory you have, if you bump NMBCLUSTERS to 4k, bump

Manuel Bouyer, LIP6, Universite Paris VI.