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From: Poul-Henning Kamp <phk@ref.tfs.com>
Message-Id: <199503100911.BAA03127@ref.tfs.com>
Subject: Basic Block Profiling in the kernel
To: current@FreeBSD.org
Date: Fri, 10 Mar 1995 01:11:46 -0800 (PST)
Cc: faq@FreeBSD.org
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To use basic-block profiling on the kernel follow these steps:

0.  Recompile & install 
	src/gnu/usr.bin/cc
	src/usr.sbin/kernbb

1.  Compile your kernel.  The source files you want to profile must be
    compiled with "-g -a" in CFLAGS.

3.  "strip -x kernel", install and reboot

4.  Run the machine through its paces, and torture it as you want to excercise
    the code.
    
5.  Run the "kernbb" program:

	kernbb > /some/where

    the output can be up to a couple of megabytes on the format:

	../../ddb/db_aout.c   108 X_db_sym_init 4027583916 3108

    The fields are:
	source file (relative to /sys/compile/<KERNEL>
	line number
	function
	address in decimal
	number of times executed.

6.  You can use this tcl program to merge the counts into the source:

	sort /some/where | tcl merge.tcl > /some/place/else

    you can grep on funtions and filenames to limit the output:

	grep comwakeup /some/where | sort | tcl merge.tcl > /some/place/else
   
    Here is the code I use:  merge.tcl

	#!/usr/local/bin/tcl

	# change to your kernel compile directory
	set dir "/sys/compile/FLAGMOSE"

	set line "----------------------------------------------"
	set m 0
	set f ""
	while 1 {
		set i ""
		set j [gets stdin b]
		if {[lindex $b 0] != $f} {
			if {$f != ""} {
				set p [open $dir/$f]
				set k 0
				puts ""
				puts [string range $line 1 [string length $f]]
				puts $f
				puts stderr "doing $f"
				puts [string range $line 1 [string length $f]]
				for {set i 1} {$i <= $m || $k >= 0} {incr i} {
					set x ""
					catch {set x $lno($i)}
					set lno($i) ""
					set k [gets $p l]
					puts [format "%5u|%-20s|%s"  $i $x $l]
				}
				close $p
			}
			set m 0
			set f [lindex $b 0]
		} else {
			set l [lindex $b 1]
			append lno($l) "[lindex $b 4] "
			if {$l > $m} {set m $l}
		}
		if {$j < 0} break
	}
   	


-- 
Poul-Henning Kamp <phk@login.dknet.dk> -- TRW Financial Systems, Inc.
'All relevant people are pertinent' && 'All rude people are impertinent'
=> 'no rude people are relevant'