Thanks to the only answer: sunven!emsca!lsp@Venezuela.Sun.COM.
Q: How do I find the value used on my running system?:
A: You can use an adb script like this:
-------> cut here <---------
#! /bin/sh
#
# Buffer Cache values in the Solaris 2.3 Kernel
#
adb -k /dev/ksyms /dev/mem << EOF
="Buffer Cache Parameters"
="**********************"
=""
*nbuf=D"How many page sized buffers have been allocated"
*nhbuf=D"How many buffers headers"
*p_nbuf=D"How many new buffers are allocated in one go"
*bufhwm=D"Maximum amount of memory allocated to the buffer (Kbytes)"
EOF
-------> cut here <---------
Q: What is this parameter bufhwm?
A: The variable bufhwm controls the maximum amount of memory allocated
to the buffer and is specified in Kbytes. By default up to 2% of
the system memory is used, this can be increased to 20%,and it will
be usually need to be increased to 10% for a dedicated NFS server.
Q: Is it worth changing the default value of this parameter?
A: Buffer Cache can be monitored using "sar -b", this reports a read
and a write hit rate for the buffer cache. The buffer cache size
(bufhwm) should be increased if there are significant ( say more
than 50 ) number of reads and writes per second and the read hit
rate falls below 90% or the write hit rate falls below 65%.
Also you can use and undocumented option of the netstat command
"netstat -k" and calculate the hist rate in this form:
% Hit rate = buffer cache hits/buffer cache lookups
Jacques Beigbeder | Internet: beig@ens.fr
Service de Prestations Informatiques |
Ecole Normale Superieure |
45 rue d'Ulm | Tel : (33-1) 44-32-37-96
F75230 Paris Cedex 05 | Fax : (33-1) 44-32-20-80
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