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Diffstat (limited to 'Documentation/basic_profiling.txt')
| -rw-r--r-- | Documentation/basic_profiling.txt | 52 |
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diff --git a/Documentation/basic_profiling.txt b/Documentation/basic_profiling.txt new file mode 100644 index 00000000000..65e3dc2d443 --- /dev/null +++ b/Documentation/basic_profiling.txt @@ -0,0 +1,52 @@ +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! + +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 + <test> +dump output readprofile -m /boot/System.map > captured_profile + +Oprofile +-------- +Get the source (I use 0.8) 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 + <test> +stop opcontrol --stop +dump output opreport > output_file + +To only report on the kernel, run opreport /boot/vmlinux > output_file + +A reset is needed to clear old statistics, which survive a reboot. + |