dtrace discuss - Dec 2005 - Measuring Apache module function processing time

Howdy,

I wrote the following [1][2] DTrace script to measure Apache module 
processing time, and was curious if there are better ways to go about 
implementing this? I assume there are, and would love to get feedback.

Thanks for any insight,
- Ryan
--
UNIX Administrator
http://daemons.net/~matty

[1] Execution

$ moduletrace `pgrep httpd | head -1` mod_alias.so
Tracing Apache Module mod_alias.so (Control-C to stop)
^C
Module                Function                        Time
mod_alias.so          alias_matches                   582737
mod_alias.so          fixup_redir                     602225
mod_alias.so          translate_alias_redir           859978
mod_alias.so          try_alias_list                  1124218

Total Time:           3169158

[2] Script

$ cat moduletrace
#!/usr/bin/ksh

if [ $# -ne 2 ]
then
     echo "Usage: $0 HTTPD_PID MODULE_NAME"
     echo "       (e.g., $0 \`pgrep httpd\` mod_ssl.so)"
     exit 1
fi

apache_module=$2

/usr/sbin/dtrace -q -p $1 -n''

inline string APACHE_MODULE_NAME     =
"''$apache_module''";

dtrace:::BEGIN
{
     printf("Tracing Apache Module %s (Control-C to
stop)\n",APACHE_MODULE_NAME);
}

pid$target:::entry
/ probemod == APACHE_MODULE_NAME /
{
    functions[probefunc] = 1;
    self->ts = timestamp;
}

pid$target:::return
/ functions[probefunc] /
{
    self->current_time = timestamp - self->ts;

    @time[probemod, probefunc] = sum(self->current_time);
    @total_time["Total Time:"] = sum(self->current_time);
}

dtrace:::END
{
    printf("%-20s  %-30s  %-10s\n","Module",
"Function", "Time");
    printa("%-20s  %-30s  %- at d\n", @time);
    printa("\n%-20s  %- at d\n", @total_time);
}''