readprofile8

Usage

Version

This manpage documents version 2.0 of the program.

Overview

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.

This utility is a diagnostic tool and is not designed or intended for use in security-sensitive contexts (e.g., setuid, setgid, sudo, or similar privilege-elevation scenarios). It is installed without any special permissions.

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 /boot/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.

-n, --no-auto

Disable automatic byte order detection.

-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.

-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

/usr/src/linux/System.map

/usr/src/linux/*

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 '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:

   readprofile -M 20