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Date:      Sat, 05 May 2001 11:43:10 +0100
From:      Ian Dowse <iedowse@maths.tcd.ie>
To:        David Costa <dcosta@gothamnetworks.com>
Cc:        "'freebsd-questions@freebsd.org'" <freebsd-questions@freebsd.org>
Subject:   Re: netstat -m indicates high percentage usage by network 
Message-ID:   <200105051143.aa68947@salmon.maths.tcd.ie>
In-Reply-To: Your message of "Fri, 04 May 2001 15:57:19 EDT." <A513B87D06E2D211906000508B951240133ABA@mail1.gothamnetworks.com> 

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In message <A513B87D06E2D211906000508B951240133ABA@mail1.gothamnetworks.com>, D
avid Costa writes:
>
>I am running a freeBSD 4.0 system with 128 MB of RAM, an Adaptec AN-62044
>Quad Ethernet card, and A Fore PCA-200e ATM card running the Fore driver.
>I have rebuilt the kernel and increased the maxusers parameter from 32 to
>64, and yet the netstat -m output always indicates high usage by the network

>914/1152/6144 mbufs in use (current/peak/max):
>        906 mbufs allocated to data
>        8 mbufs allocated to packet headers
>887/918/1536 mbuf clusters in use (current/peak/max)
>1980 Kbytes allocated to network (95% in use)

The 95% here is nothing to worry about; it is simply saying that
of all the memory currently allocated to mbuf storage, 95% is being
used. If this reaches 100%, then more memory will be automatically
allocated, up to the hard `max' limits listed above.

The real numbers of interest in the output of `netstat -m' are

	914/1152/6144 mbufs in use (current/peak/max)
	887/918/1536 mbuf clusters in use (current/peak/max)

This tells you that you're okay for mbufs (current 15%, max 20%),
but that the cluster usage is quite high (approx 60%) - this is
probably caused by the memory reserved by each network card for
receive buffers. Increasing maxusers or setting NMBCLUSTERS to
around 6000 (see the example in LINT) should improve the situation.

Ian

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