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Date:      Wed, 21 Aug 2002 17:30:48 +0100 (BST)
From:      Gavin Atkinson <gavin@ury.york.ac.uk>
To:        <freebsd-stable@freebsd.org>
Cc:        <dillon@freebsd.org>
Subject:   mbuf usage - how do i track it down?
Message-ID:  <Pine.BSF.4.33.0208211647430.22899-100000@ury.york.ac.uk>

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Hi,

I'm having problems on 4.6-STABLE, with running out of mbufs. I have in
the past had problems with running out of mbuf clusters, but have since
upped that from 1024 to 4096 with kern.ipc.nmbclusters="4096" in
/boot/loader.conf. I now find I am running out of mbufs.

endor# netstat -m
16288/16384/16384 mbufs in use (current/peak/max):
        16227 mbufs allocated to data
        3 mbufs allocated to packet headers
        58 mbufs allocated to socket names and addresses
291/1742/4096 mbuf clusters in use (current/peak/max)
7580 Kbytes allocated to network (61% of mb_map in use)
30504 requests for memory denied
9746 requests for memory delayed
12606 calls to protocol drain routines

I have upped it to 32768 with kern.ipc.nmbufs="32768" in
/boot/loader.conf, but as soon as I did that I found I was frequently
getting "No buffer space available" messages while trying to create some
outgoing TCP connections. However, after commenting the line out and
rebooting, i am still getting these messages so they may not be related.

This box is acting as a nat gateway, with an adsl usb mopdem attached, and
an fxp card for the internal network. Currently I have a maximum uptiime
of around 8 days before I need to reboot because of the leaking mbufs.

So how do I find out what is actually allocating these mbufs. Something
seems to be leaking them.

How do I try to debug this? I need to know what is allocating these. The
mbuf(9) man page reffered to in stable doesn't exist, and under current it
doesn't really provide any pointers as to where i should go from here.

I don't really want to just blindly up the number of mbufs, something is
obviously leaking here. I want to solve the problem, by finding out what.

I can give access to this box if needed, it is one ill machine.

Gavin


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