# readprofile

## 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
    


## AVAILABILITY



           The **readprofile** command is part of the util-linux package which
           can be downloaded from Linux Kernel Archive
           <https://www.kernel.org/pub/linux/utils/util-linux/>. This page is
           part of the _util-linux_ (a random collection of Linux utilities)
           project. Information about the project can be found at 
           ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you have a
           bug report for this manual page, send it to
           util-linux@vger.kernel.org. This page was obtained from the
           project's upstream Git repository
           ⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
           2025-08-11. (At that time, the date of the most recent commit that
           was found in the repository was 2025-08-05.) If you discover any
           rendering problems in this HTML version of the page, or you
           believe there is a better or more up-to-date source for the page,
           or you have corrections or improvements to the information in this
           COLOPHON (which is _not_ part of the original manual page), send a
           mail to man-pages@man7.org
    
    util-linux 2.42-start-521-ec46  2025-01-16                 _READPROFILE_(8)
    


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