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Date:      Fri, 07 Mar 2003 10:58:23 -0800
From:      Terry Lambert <tlambert2@mindspring.com>
To:        Bruce Cran <bruce@cran.org.uk>
Cc:        hackers@freebsd.org
Subject:   Re: High CPU usage when forwarding packets
Message-ID:  <3E68EBCF.E19242C1@mindspring.com>
References:  <20030307131038.GA919@fourtytwo.brucec.backnet>

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Bruce Cran wrote:
> Also, I'm getting
> several thousand 'lnc0: Missed packet -- no receive buffer' messages.
> Could this be the problem, or is the system just not powerful enough do
> nat?  The sis0 card is 100MBit PCI, while the lcn0 is 10MBit ISA.

The "no receive buffers available" message happens when the
system runs out of mbufs.

There are a lot of reasons this could happen, but the proximal
cause is you didn't tune the number NMBCLUSTERS, et. al. high
enough.  You should try rebuilding your kernel with a larger
number.

If the problem still happens, you need to do a "netstat -a > x",
and then look for large numbers in the "Recv-Q" and "Send-Q"
columns, and then figure out what's causing them.

-- Terry

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