view Documentation/basic_profiling.txt @ 912:dd42cdb0ab89

[IA64] Build blktap2 driver by default in x86 builds.

add CONFIG_XEN_BLKDEV_TAP2=y to buildconfigs/linux-defconfig_xen_ia64.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
author Isaku Yamahata <yamahata@valinux.co.jp>
date Mon Jun 29 12:09:16 2009 +0900 (2009-06-29)
parents 831230e53067
line source
1 These instructions are deliberately very basic. If you want something clever,
2 go read the real docs ;-) Please don't add more stuff, but feel free to
3 correct my mistakes ;-) (mbligh@aracnet.com)
4 Thanks to John Levon, Dave Hansen, et al. for help writing this.
6 <test> is the thing you're trying to measure.
7 Make sure you have the correct System.map / vmlinux referenced!
9 It is probably easiest to use "make install" for linux and hack
10 /sbin/installkernel to copy vmlinux to /boot, in addition to vmlinuz,
11 config, System.map, which are usually installed by default.
13 Readprofile
14 -----------
15 A recent readprofile command is needed for 2.6, such as found in util-linux
16 2.12a, which can be downloaded from:
18 http://www.kernel.org/pub/linux/utils/util-linux/
20 Most distributions will ship it already.
22 Add "profile=2" to the kernel command line.
24 clear readprofile -r
25 <test>
26 dump output readprofile -m /boot/System.map > captured_profile
28 Oprofile
29 --------
31 Get the source (see Changes for required version) from
32 http://oprofile.sourceforge.net/ and add "idle=poll" to the kernel command
33 line.
35 Configure with CONFIG_PROFILING=y and CONFIG_OPROFILE=y & reboot on new kernel
37 ./configure --with-kernel-support
38 make install
40 For superior results, be sure to enable the local APIC. If opreport sees
41 a 0Hz CPU, APIC was not on. Be aware that idle=poll may mean a performance
42 penalty.
44 One time setup:
45 opcontrol --setup --vmlinux=/boot/vmlinux
47 clear opcontrol --reset
48 start opcontrol --start
49 <test>
50 stop opcontrol --stop
51 dump output opreport > output_file
53 To only report on the kernel, run opreport -l /boot/vmlinux > output_file
55 A reset is needed to clear old statistics, which survive a reboot.