READPROFILE(1)							READPROFILE(1)



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  isnt 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.


       -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 kernels	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 wouldnt 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 :-)




4th Berkeley Distribution	   May 1996			READPROFILE(1)