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Date:      Wed, 12 Aug 1998 08:52:13 -0700
From:      David Greenman <dg@root.com>
To:        josh <josh@lucratec.com>
Cc:        freebsd-questions@FreeBSD.ORG
Subject:   Re: kmem_map too small 
Message-ID:  <199808121552.IAA26465@implode.root.com>
In-Reply-To: Your message of "Wed, 12 Aug 1998 09:33:43 CDT." <35D1A7C7.5A44E4E@lucratec.com> 

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>http://www.freebsd.org/FAQ/FAQ83.html#83
>
>On this url in order to avoid this PANIC addressed in my subject, I
>upped my NMBCLUSTERS to '25000'
>
>Yes, 25,000.  On a machine with 1 gig of ram.
>
>Using netstat -m I see this:
>
>4747 mbufs in use:
>        3174 mbufs allocated to data
>        1563 mbufs allocated to packet headers
>        7 mbufs allocated to protocol control blocks
>        3 mbufs allocated to socket names and addresses
>3083/3640 mbuf clusters in use
>7873 Kbytes allocated to network (85% in use)
>0 requests for memory denied
>0 requests for memory delayed
>0 calls to protocol drain routines
>
>Usually, 99% is in use, and then my system panics and reboots itself.
>
>What the hell do I need to set my nmbclusters to have enough mbuf
>clusters?
>
>100,000 nmb clusters????

   "kmem_map too small" panic is not an indication of running out of mbuf
clusters. It's an indication of running out of malloc space. You need to
increase VM_KMEM_SIZE to something larger than the default of 32MB. I'd try
doubling it.
   As to other things you've said above: An in-use percent of 99% does not
indicate that you are out of buffers. It's a mostly bogus number that tells
you how much is in-use of the peak since the system was started. The peak
is the second number in the line above that. In your netstat output above,
your system has peaked usage of 3640 mbuf clusters. If this doesn't increase
significantly over time, then you will only need to configure perhaps 5000-
6000 mbuf clusters to keep your system happy (always plan for at least
1.5-2*peak).

-DG

David Greenman
Co-founder/Principal Architect, The FreeBSD Project

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