#
# dnlcstat - DNLC statistics.
# Written in DTrace (Solaris 10 3/05).
#
# The DNLC is the Directory Name Lookup Cache. Filename lookups often
# return a hit from here, before needing to traverse the regular file
# system cache or go to disk.
#
# $Id: dnlcstat 3 2007-08-01 10:50:08Z brendan $
#
# USAGE: dnlcstat [interval [count]]
#
# FIELDS:
#
# %hit hit percentage for this sample
# hit number of DNLC hits in this sample
# miss number of DNLC misses in this sample
#
# SEE ALSO: CacheKit, http://www.brendangregg.com/cachekit.html
# (contains a dnlcstat written in Perl, which uses less CPU)
#
# COPYRIGHT: Copyright (c) 2005 Brendan Gregg.
#
# CDDL HEADER START
#
# The contents of this file are subject to the terms of the
# Common Development and Distribution License, Version 1.0 only
# (the "License"). You may not use this file except in compliance
# with the License.
#
# See the License for the specific language governing permissions
# and limitations under the License.
#
# CDDL HEADER END
#
# 27-Mar-2004 Brendan Gregg Created this.
# 14-Jun-2005 " " Updated style.
# 14-Jun-2005 " " Last update.
#
##############################
# --- Process Arguments ---
#
### default values
### check arguments
if [ "$1" = "-h" -o "$1" = "--help" ]; then
cat <<-END >&2
USAGE: dnlcstat [interval [count]]
dnlcstat # 1 second samples, infinite
eg,
dnlcstat 1 # print every 1 second
dnlcstat 5 6 # print every 5 seconds, 6 times
END
exit 1
fi
### argument logic
if [ "$1" -gt 0 ]; then
interval=$1; count=-1; shift
fi
if [ "$1" -gt 0 ]; then
count=$1; shift
fi
if [ $interval -eq 0 ]; then
interval=1
fi
#################################
# --- Main Program, DTrace ---
#
/usr/sbin/dtrace -n '
#pragma D option quiet
/*
* Command line arguments
*/
inline int INTERVAL = '$interval';
inline int COUNTER = '$count';
inline int SCREEN = 21;
int hits; /* hits */
int misses; /* misses */
/*
* Initialise variables
*/
dtrace:::BEGIN
{
lines = SCREEN + 1;
counts = COUNTER;
secs = INTERVAL;
first = 1;
}
/*
* Print header
*/
dtrace:::BEGIN,
tick-1sec
/first || (secs == 0 && lines > SCREEN)/
{
printf("%10s %8s %8s\n","dnlc %hit","hit","miss");
lines = 0;
first = 0;
}
/*
* Probe DNLC lookups
*/
fbt:genunix:dnlc_lookup:return
{
hits += arg1 == 0 ? 0 : 1;
misses += arg1 == 0 ? 1 : 0;
}
profile:::tick-1sec
{
secs--;
}
/*
* Print output line
*/
profile:::tick-1sec
/secs == 0/
{
/* calculate hit percent */
this->divide = misses + hits == 0 ? 1 : misses + hits;
ratio = hits * 100 / this->divide;
/* print output */
printf("%10d %8d %8d\n",ratio,hits,misses);
/* clear counters */
hits = 0;
misses = 0;
/* process counts */
secs = INTERVAL;
counts--;
lines++;
}
/*
* End
*/
profile:::tick-1sec
/counts == 0/
{
exit(0);
}
'