Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/Documentation/basic_profiling.txt
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 1677 byte(s)
Tag kernel26-2.6.12-alx-r9
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. |
5 | |
6 | <test> is the thing you're trying to measure. |
7 | Make sure you have the correct System.map / vmlinux referenced! |
8 | |
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. |
12 | |
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: |
17 | |
18 | http://www.kernel.org/pub/linux/utils/util-linux/ |
19 | |
20 | Most distributions will ship it already. |
21 | |
22 | Add "profile=2" to the kernel command line. |
23 | |
24 | clear readprofile -r |
25 | <test> |
26 | dump output readprofile -m /boot/System.map > captured_profile |
27 | |
28 | Oprofile |
29 | -------- |
30 | Get the source (I use 0.8) from http://oprofile.sourceforge.net/ |
31 | and add "idle=poll" to the kernel command line |
32 | Configure with CONFIG_PROFILING=y and CONFIG_OPROFILE=y & reboot on new kernel |
33 | ./configure --with-kernel-support |
34 | make install |
35 | |
36 | For superior results, be sure to enable the local APIC. If opreport sees |
37 | a 0Hz CPU, APIC was not on. Be aware that idle=poll may mean a performance |
38 | penalty. |
39 | |
40 | One time setup: |
41 | opcontrol --setup --vmlinux=/boot/vmlinux |
42 | |
43 | clear opcontrol --reset |
44 | start opcontrol --start |
45 | <test> |
46 | stop opcontrol --stop |
47 | dump output opreport > output_file |
48 | |
49 | To only report on the kernel, run opreport /boot/vmlinux > output_file |
50 | |
51 | A reset is needed to clear old statistics, which survive a reboot. |
52 |