Commit 39773b6e authored by Martin J. Bligh's avatar Martin J. Bligh Committed by Linus Torvalds

[PATCH] 5/6 Provide basic documentation for profiling

People keep asking for this info, and Andrew asked me to put it under the
Documentation directory ... provides really simple instructions for taking
a profile so that users can report performance changes in a useful way.
parent 1e5cf911
These instructions are deliberately very basic. If you want something clever,
go read the real docs ;-) Please don't add more stuff, but feel free to
correct my mistakes ;-) (mbligh@aracnet.com)
Thanks to John Levon, Dave Hansen, et al. for help writing this.
<test> is the thing you're trying to measure.
Make sure you have the correct System.map / vmlinux referenced!
IMHO it's easier to use "make install" for linux and hack /sbin/installkernel
to copy config files, system.map, vmlinux to /boot.
Readprofile
-----------
You need a fixed readprofile command for 2.5 ... either get hold of
a current version from:
http://www.kernel.org/pub/linux/utils/util-linux/
or get readprofile binary fixed for 2.5 / akpm's 2.5 patch from
ftp://ftp.kernel.org/pub/linux/kernel/people/mbligh/tools/readprofile/
Add "profile=2" to the kernel command line.
clear readprofile -r
<test>
dump output readprofile -m /boot/System.map > captured_profile
Oprofile
--------
get source (I use 0.5) from http://oprofile.sourceforge.net/
add "idle=poll" to the kernel command line
Configure with CONFIG_PROFILING=y and CONFIG_OPROFILE=y & reboot on new kernel
./configure --with-kernel-support
make install
One time setup (pick appropriate one for your CPU):
P3 opcontrol --setup --vmlinux=/boot/vmlinux \
--ctr0-event=CPU_CLK_UNHALTED --ctr0-count=100000
Athlon/x86-64 opcontrol --setup --vmlinux=/boot/vmlinux \
--ctr0-event=RETIRED_INSNS --ctr0-count=100000
P4 opcontrol --setup --vmlinux=/boot/vmlinux \
--ctr0-event=GLOBAL_POWER_EVENTS \
--ctr0-unit-mask=1 --ctr0-count=100000
start daemon opcontrol --start-daemon
clear opcontrol --reset
start opcontrol --start
<test>
stop opcontrol --stop
dump output oprofpp -dl -i /boot/vmlinux > output_file
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