Manual: readprofile

READPROFILE(8)					    System Administration				      READPROFILE(8)

NAME
       readprofile - read kernel profiling information

SYNOPSIS
       readprofile [options]

VERSION
       This manpage documents version 2.0 of the program.

DESCRIPTION
       The readprofile command uses the /proc/profile information to print ascii data on standard output. The output is
       organized in three columns: the first is the number of clock ticks, the second is the name of the C function in the
       kernel where those many ticks occurred, and the third is the normalized `load' of the procedure, calculated as a
       ratio between the number of ticks and the length of the procedure. The output is filled with blanks to ease
       readability.

OPTIONS
       -a, --all
	   Print all symbols in the mapfile. By default the procedures with reported ticks are not printed.

       -b, --histbin
	   Print individual histogram-bin counts.

       -i, --info
	   Info. This makes readprofile only print the profiling step used by the kernel. The profiling step is the
	   resolution of the profiling buffer, and is chosen during kernel configuration (through make config), or in the
	   kernel’s command line. If the -t (terse) switch is used together with -i only the decimal number is printed.

       -m, --mapfile mapfile
	   Specify a mapfile, which by default is /usr/src/linux/System.map. You should specify the map file on cmdline if
	   your current kernel isn’t the last one you compiled, or if you keep System.map elsewhere. If the name of the map
	   file ends with .gz it is decompressed on the fly.

       -M, --multiplier multiplier
	   On some architectures it is possible to alter the frequency at which the kernel delivers profiling interrupts to
	   each CPU. This option allows you to set the frequency, as a multiplier of the system clock frequency, HZ. Linux
	   2.6.16 dropped multiplier support for most systems. This option also resets the profiling buffer, and requires
	   superuser privileges.

       -p, --profile pro-file
	   Specify a different profiling buffer, which by default is /proc/profile. Using a different pro-file is useful if
	   you want to `freeze' the kernel profiling at some time and read it later. The /proc/profile file can be copied
	   using cat(1) or cp(1). There is no more support for compressed profile buffers, like in readprofile-1.1, because
	   the program needs to know the size of the buffer in advance.

       -r, --reset
	   Reset the profiling buffer. This can only be invoked by root, because /proc/profile is readable by everybody but
	   writable only by the superuser. However, you can make readprofile set-user-ID 0, in order to reset the buffer
	   without gaining privileges.

       -s, --counters
	   Print individual counters within functions.

       -v, --verbose
	   Verbose. The output is organized in four columns and filled with blanks. The first column is the RAM address of a
	   kernel function, the second is the name of the function, the third is the number of clock ticks and the last is
	   the normalized load.

       -h, --help
	   Display help text and exit.

       -V, --version
	   Display version and exit.

FILES
       /proc/profile
	   A binary snapshot of the profiling buffer.

       /usr/src/linux/System.map
	   The symbol table for the kernel.

       /usr/src/linux/*
	   The program being profiled :-)

BUGS
       readprofile only works with a 1.3.x or newer kernel, because /proc/profile changed in the step from 1.2 to 1.3.

       This program only works with ELF kernels. The change for a.out kernels is trivial, and left as an exercise to the
       a.out user.

       To enable profiling, the kernel must be rebooted, because no profiling module is available, and it wouldn’t be easy
       to build. To enable profiling, you can specify profile=2 (or another number) on the kernel commandline. The number
       you specify is the two-exponent used as profiling step.

       Profiling is disabled when interrupts are inhibited. This means that many profiling ticks happen when interrupts are
       re-enabled. Watch out for misleading information.

EXAMPLE
       Browse the profiling buffer ordering by clock ticks:

	      readprofile | sort -nr | less

       Print the 20 most loaded procedures:

	      readprofile | sort -nr +2 | head -20

       Print only filesystem profile:

	      readprofile | grep _ext2

       Look at all the kernel information, with ram addresses:

	      readprofile -av | less

       Browse a 'frozen' profile buffer for a non current kernel:

	      readprofile -p ~/profile.freeze -m /zImage.map.gz

       Request profiling at 2kHz per CPU, and reset the profiling buffer:

	      sudo readprofile -M 20

REPORTING BUGS
       For bug reports, use the issue tracker .

AVAILABILITY
       The readprofile command is part of the util-linux package which can be downloaded from Linux Kernel Archive
       .

util-linux 2.41.3					 2025-12-15					      READPROFILE(8)