basic_profiling.txt 1.7 KB

1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556
  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. <test> is the thing you're trying to measure.
  6. Make sure you have the correct System.map / vmlinux referenced!
  7. It is probably easiest to use "make install" for linux and hack
  8. /sbin/installkernel to copy vmlinux to /boot, in addition to vmlinuz,
  9. config, System.map, which are usually installed by default.
  10. Readprofile
  11. -----------
  12. A recent readprofile command is needed for 2.6, such as found in util-linux
  13. 2.12a, which can be downloaded from:
  14. http://www.kernel.org/pub/linux/utils/util-linux/
  15. Most distributions will ship it already.
  16. Add "profile=2" to the kernel command line.
  17. clear readprofile -r
  18. <test>
  19. dump output readprofile -m /boot/System.map > captured_profile
  20. Oprofile
  21. --------
  22. Get the source (see Changes for required version) from
  23. http://oprofile.sourceforge.net/ and add "idle=poll" to the kernel command
  24. line.
  25. Configure with CONFIG_PROFILING=y and CONFIG_OPROFILE=y & reboot on new kernel
  26. ./configure --with-kernel-support
  27. make install
  28. For superior results, be sure to enable the local APIC. If opreport sees
  29. a 0Hz CPU, APIC was not on. Be aware that idle=poll may mean a performance
  30. penalty.
  31. One time setup:
  32. opcontrol --setup --vmlinux=/boot/vmlinux
  33. clear opcontrol --reset
  34. start opcontrol --start
  35. <test>
  36. stop opcontrol --stop
  37. dump output opreport > output_file
  38. To only report on the kernel, run opreport -l /boot/vmlinux > output_file
  39. A reset is needed to clear old statistics, which survive a reboot.