/Documentation/basic_profiling.txt

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  1. These instructions are deliberately very basic. If you want something clever,
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  2. go read the real docs ;-) Please don't add more stuff, but feel free to 
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  3. correct my mistakes ;-)    (mbligh@aracnet.com)
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  4. Thanks to John Levon, Dave Hansen, et al. for help writing this.
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  6. <test> is the thing you're trying to measure.
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  7. Make sure you have the correct System.map / vmlinux referenced!
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  9. It is probably easiest to use "make install" for linux and hack
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  10. /sbin/installkernel to copy vmlinux to /boot, in addition to vmlinuz,
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  11. config, System.map, which are usually installed by default.
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  13. Readprofile
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  14. -----------
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  15. A recent readprofile command is needed for 2.6, such as found in util-linux
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  16. 2.12a, which can be downloaded from:
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  18. http://www.kernel.org/pub/linux/utils/util-linux/
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  20. Most distributions will ship it already.
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  22. Add "profile=2" to the kernel command line.
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  24. clear		readprofile -r
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  25. 		<test>
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  26. dump output	readprofile -m /boot/System.map > captured_profile
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  28. Oprofile
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  29. --------
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  30. Get the source (I use 0.8) from http://oprofile.sourceforge.net/
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  31. and add "idle=poll" to the kernel command line
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  32. Configure with CONFIG_PROFILING=y and CONFIG_OPROFILE=y & reboot on new kernel
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  33. ./configure --with-kernel-support
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  34. make install
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  36. For superior results, be sure to enable the local APIC. If opreport sees
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  37. a 0Hz CPU, APIC was not on. Be aware that idle=poll may mean a performance
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  38. penalty.
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  40. One time setup:
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  41. 		opcontrol --setup --vmlinux=/boot/vmlinux
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  43. clear		opcontrol --reset
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  44. start		opcontrol --start
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  45. 		<test>
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  46. stop		opcontrol --stop
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  47. dump output	opreport >  output_file
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  49. To only report on the kernel, run opreport /boot/vmlinux > output_file
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  51. A reset is needed to clear old statistics, which survive a reboot.
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