10.4;mbd (memory buffer dump), revision 2.0, 91/05/31
mbd (memory buffer dump)- dump usage info on tcp buffer pool
usage: /etc/mbd [-d] [-f] [-n]
DESCRIPTION
The mbd command dumps usage information about the tcp memory buffer
pools. Usage statistics on tcp memory buffers may be obtained by using
the -m option of the netstat command; mbd is intended for analyzing cases
where buffers are being lost. It scans the entire buffer pool, finding
all the chains of in-use buffers; it then prints each chain of buffers.
This information may help you in discovering reasons why buffers are
being lost.
OPTIONS
-d Dump the data contents (in hexadecimal) of the mbufs.
-f Dump the free pools as well as the chains of in-use buffers. This
option produces a lot of output.
-n Don't try to lock the mutex on the buffer pools before doing the
dump. This is useful mostly when the tcpd has crashed with the
buffer pool mutex locked.
EXAMPLES
A dump of the buffer pools of a basically idle tcp might look like this:
$ /etc/mbd
Offset 0x000035cc size 1520 type 1 off 24 len 1512 refcnt 1 pool 1
Offset 0x000041cc size 1520 type 1 off 24 len 1512 refcnt 1 pool 1
Offset 0x00003bcc size 1520 type 1 off 24 len 1512 refcnt 1 pool 1
Offset 0x0000a7cc size 1520 type 1 off 24 len 1512 refcnt 1 pool 1
Offset 0x00004dcc size 1520 type 1 off 24 len 1512 refcnt 1 pool 1
Offset 0x00007dcc size 1520 type 1 off 24 len 1512 refcnt 1 pool 1
Here there are 6 large (1520-byte) buffers in use, all on a single chain.