diff --git a/Documentation/basic_profiling.txt b/Documentation/basic_profiling.txt index 8764e9f70821..15a49dbd0189 100644 --- a/Documentation/basic_profiling.txt +++ b/Documentation/basic_profiling.txt @@ -1,56 +1,69 @@ +Basic kernel profiling +====================== + + 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 +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. - is the thing you're trying to measure. -Make sure you have the correct System.map / vmlinux referenced! +```` 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. +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 + +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/ + http://www.kernel.org/pub/linux/utils/util-linux/ Most distributions will ship it already. -Add "profile=2" to the kernel command line. +Add ``profile=2`` to the kernel command line. -clear readprofile -r - -dump output readprofile -m /boot/System.map > captured_profile +Some ``readprofile`` commands:: + + 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 +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 ``CONFIG_PROFILING=y`` and ``CONFIG_OPROFILE=y`` & reboot on new kernel:: -./configure --with-kernel-support -make install + ./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 +One time setup:: -clear opcontrol --reset -start opcontrol --start + opcontrol --setup --vmlinux=/boot/vmlinux + +Some ``opcontrol`` commands:: + + clear opcontrol --reset + start opcontrol --start -stop opcontrol --stop -dump output opreport > output_file + stop opcontrol --stop + dump output opreport > output_file -To only report on the kernel, run opreport -l /boot/vmlinux > 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.