From a1df417e74aa6dae7352dc8cbb0ad471af5b7c69 Mon Sep 17 00:00:00 2001 From: "Michael J. Chudobiak" Date: Mon, 25 Apr 2016 10:00:44 -0400 Subject: initial Olimex linux tree from Daniel, originally Feb 3, 2016 --- linux/Documentation/basic_profiling.txt | 56 +++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) create mode 100644 linux/Documentation/basic_profiling.txt (limited to 'linux/Documentation/basic_profiling.txt') diff --git a/linux/Documentation/basic_profiling.txt b/linux/Documentation/basic_profiling.txt new file mode 100644 index 00000000..8764e9f7 --- /dev/null +++ b/linux/Documentation/basic_profiling.txt @@ -0,0 +1,56 @@ +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. + + 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 + +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. + -- cgit