running out of mbufs?

[Kris Kennaway]

On Wed, Aug 03, 2005 at 01:49:32PM +1000, Dave+Seddon wrote:
> Greetings,
> 
> I'm trying to do some performance testing of a content filtering system, so
> I'm trying to get very high HTTP throughput.  I've got 4 * HP DL380s with
> 3.4G Xeon processors (hyper threading) and 1 G RAM, 2 onboard BGEs, and 2 *
> 2 port EM.  Using FreeBSD5.4-stable (as of 2005/08/02) and device polling,
> I've configured a large number (246) VLAN interfaces on two machines, and
> have apache on one box and siege on the other.  Using 'siege -f
> /home/my_big_list_of_urls -c 50 --internet' one host does a large number of
> request from the other machine.  I've been trying to tune for maximum
> performance and have been using lots of examples for /etc/sysctl.conf and so
> on from the web.  Adjusting these settings and running the siege, I've found
> the apache server completely loses network connectivity when device polling
> is enabled.  I've adjusted the HZ lots and found the system survives the
> longest set a 15000 (yes it seems very large doesn't it).  The problem now
> seems to be that I'm running out of mbufs:
> 
> --------------------------------------
> 4294264419 mbufs in use
> 4294866740/2147483647 mbuf clusters in use (current/max)

This is a FAQ..see the release errata.  The short answer is that it's
not a real leak, only a leak in the stats.  This is fixed in 7.0 and
might be fixed in 6.0-RELEASE.

Kris