1READPROFILE(1)              General Commands Manual             READPROFILE(1)
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NAME

6       readprofile - a tool to read kernel profiling information
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SYNOPSIS

9       readprofile [options]
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VERSION

13       This manpage documents version 2.0 of the program.
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DESCRIPTION

17       The  readprofile  command  uses  the /proc/profile information to print
18       ascii data on standard output.  The output is organized in  three  col‐
19       umns: the first is the number of clock ticks, the second is the name of
20       the C function in the kernel where those many ticks occurred,  and  the
21       third  is the normalized `load' of the procedure, calculated as a ratio
22       between the number of ticks and the length of the procedure. The output
23       is filled with blanks to ease readability.
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26       Available command line options are the following:
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29       -m mapfile
30              Specify  a  mapfile,  which  by  default  is /usr/src/linux/Sys‐
31              tem.map.  You should specify the map file  on  cmdline  if  your
32              current  kernel  isn't the last one you compiled, or if you keep
33              System.map elsewhere. If the name of  the  map  file  ends  with
34              `.gz' it is decompressed on the fly.
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37       -p pro-file
38              Specify  a  different  profiling  buffer,  which  by  default is
39              /proc/profile.  Using a different pro-file is useful if you want
40              to `freeze' the kernel profiling at some time and read it later.
41              The /proc/profile file can be copied using `cat' or `cp'.  There
42              is no more support for compressed profile buffers, like in read‐
43              profile-1.1, because the program needs to know the size  of  the
44              buffer in advance.
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47       -i     Info.  This makes readprofile only print the profiling step used
48              by the kernel.  The profiling step is the resolution of the pro‐
49              filing   buffer,  and  is  chosen  during  kernel  configuration
50              (through `make config'), or in the kernel's  command  line.   If
51              the  -t (terse) switch is used together with -i only the decimal
52              number is printed.
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55       -a     Print all symbols in the mapfile. By default the procedures with
56              0 reported ticks are not printed.
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59       -b     Print individual histogram-bin counts.
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62       -r     Reset  the  profiling  buffer. This can only be invoked by root,
63              because /proc/profile is readable by everybody but writable only
64              by the superuser. However, you can make readprofile setuid 0, in
65              order to reset the buffer without gaining privileges.
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68       -M multiplier
69              On some architectures it is possible to alter the  frequency  at
70              which  the  kernel  delivers  profiling  interrupts to each CPU.
71              This option allows you to set the frequency, as a multiplier  of
72              the  system  clock frequency, HZ.  This is supported on i386-SMP
73              (2.2 and 2.4 kernel) and also on sparc-SMP and sparc64-SMP  (2.4
74              kernel).   This  option  also  resets  the profiling buffer, and
75              requires superuser privileges.
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78       -v     Verbose. The output is organized in four columns and filled with
79              blanks.   The  first column is the RAM address of a kernel func‐
80              tion, the second is the name of the function, the third  is  the
81              number of clock ticks and the last is the normalized load.
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84       -V     Version.  This  makes  readprofile  print its version number and
85              exit.
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EXAMPLES

89       Browse the profiling buffer ordering by clock ticks:
90          readprofile | sort -nr | less
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92       Print the 20 most loaded procedures:
93          readprofile | sort -nr +2 | head -20
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95       Print only filesystem profile:
96          readprofile | grep _ext2
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98       Look at all the kernel information, with ram addresses"
99          readprofile -av | less
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101       Browse a `freezed' profile buffer for a non current kernel:
102          readprofile -p ~/profile.freeze -m /zImage.map.gz
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104       Request profiling at 2kHz per CPU, and reset the profiling buffer
105          sudo readprofile -M 20
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BUGS

110       readprofile  only  works  with  an  1.3.x  or  newer  kernel,   because
111       /proc/profile changed in the step from 1.2 to 1.3
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114       This  program only works with ELF kernels. The change for a.out kernels
115       is trivial, and left as an exercise to the a.out user.
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118       To enable profiling, the kernel must be rebooted, because no  profiling
119       module  is  available, and it wouldn't be easy to build. To enable pro‐
120       filing, you can specify "profile=2" (or another number) on  the  kernel
121       commandline.   The  number you specify is the two-exponent used as pro‐
122       filing step.
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125       Profiling is disabled when interrupts are inhibited.  This  means  that
126       many  profiling  ticks happen when interrupts are re-enabled. Watch out
127       for misleading information.
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FILES

131       /proc/profile              A binary snapshot of the profiling buffer.
132       /usr/src/linux/System.map  The symbol table for the kernel.
133       /usr/src/linux/*           The program being profiled :-)
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AVAILABILITY

137       The readprofile command is part of the  util-linux-ng  package  and  is
138       available from ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.
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1424th Berkeley Distribution          May 1996                     READPROFILE(1)
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