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.
Make sure you have the correct System.map / vmlinux referenced!
It is probably easiest to use “make install” for linux and hack
/sbin/installkernel to copy vmlinux to /boot, in addition to vmlinuz,
config, System.map, which are usually installed by default.
Readprofile
A recent readprofile command is needed for 2.6, such as found in util-linux
2.12a, which can be downloaded from:
http://www.kernel.org/pub/linux/utils/util-linux/
Most distributions will ship it already.
Add “profile=2” to the kernel command line.
clear readprofile -r
dump output readprofile -m /boot/System.map > captured_profile
Oprofile
Get the source (see Changes for required version) from
http://oprofile.sourceforge.net/ and 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
For superior results, be sure to enable the local APIC. If opreport sees
a 0Hz CPU, APIC was not on. Be aware that idle=poll may mean a performance
penalty.
One time setup:
opcontrol –setup –vmlinux=/boot/vmlinux
clear opcontrol –reset
start opcontrol –start
stop opcontrol –stop
dump output opreport > output_file
To only report on the kernel, run opreport -l /boot/vmlinux > output_file
A reset is needed to clear old statistics, which survive a reboot.
