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Date: Fri, 7 Mar 2003 13:10:39 +0000
From: Bruce Cran <bruce@cran.org.uk>
To: hackers@freebsd.org
Subject: High CPU usage when forwarding packets
Message-ID: <20030307131038.GA919@fourtytwo.brucec.backnet>
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I've just setup a P75 system as a router, containing fa311 and pcnet network
cards.   The fa311 is doing nat to my private network, which is served by the
pcnet card.  However, I've found that it often uses 40% cpu just to send
packets from the fa311 (sis) to the pcnet (lnc) cards.  natd uses 20%, 10%
are interrupts, and 25% is 'system' as shown in top.  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.

Bruce Cran

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