NAME
    readprofile - a tool to 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.

    Available command line options are the following:

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

    -p 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' or `cp'. There
    is no more support for compressed profile buffers, like in read-
    profile-1.1, because the program needs to know the size of the
    buffer in advance.

    -i   Info. This makes readprofile only print the profiling step used
    by the kernel. The profiling step is the resolution of the pro-
    filing 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.

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

    -b   Print individual histogram-bin counts.

    -r   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 setuid 0, in
    order to reset the buffer without gaining privileges.

    -M 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. This is supported on i386-SMP
    (2.2 and 2.4 kernel) and also on sparc-SMP and sparc64-SMP (2.4
    kernel). This option also resets the profiling buffer, and
    requires superuser privileges.

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

    -V   Version. This makes readprofile print its version number and
    exit.

EXAMPLES
    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 `freezed' 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

BUGS
    readprofile  only works with an 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 pro-
    filing, you can specify "profile=2" (or another number) on the kernel
    commandline. The number you specify is the two-exponent used as pro-
    filing 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.

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 :-)