basic_profiling.txt

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    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 
   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.
   34 
   35 Configure with CONFIG_PROFILING=y and CONFIG_OPROFILE=y & reboot on new kernel
   36 
   37 ./configure --with-kernel-support
   38 make install
   39 
   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.
   43 
   44 One time setup:
   45                 opcontrol --setup --vmlinux=/boot/vmlinux
   46 
   47 clear           opcontrol --reset
   48 start           opcontrol --start
   49                 <test>
   50 stop            opcontrol --stop
   51 dump output     opreport >  output_file
   52 
   53 To only report on the kernel, run opreport -l /boot/vmlinux > output_file
   54 
   55 A reset is needed to clear old statistics, which survive a reboot.
   56

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FreeBSD/Linux Kernel Cross Reference sys/Documentation/basic_profiling.txt

FreeBSD/Linux Kernel Cross Reference
sys/Documentation/basic_profiling.txt