sys-utils/readprofile.1

   1 .TH READPROFILE 1 "May 1996"
   2 .UC 4
   3 .SH NAME
   4 readprofile - a tool to read kernel profiling information
   5 .SH SYNOPSIS
   6 .B readprofile
   7 [
   8 .I options
   9 ]
  10
  11 .SH VERSION
  12 This manpage documents version 2.0 of the program.
  13
  14 .SH DESCRIPTION
  15
  16 .LP
  17 The
  18 .B readprofile
  19 command uses the
  20 .B /proc/profile
  21 information to print ascii data on standard output.
  22 The output is
  23 organized in three columns: the first is the number of clock ticks,
  24 the second is the name of the C function in the kernel where those many
  25 ticks occurred, and the third is the normalized `load' of the procedure,
  26 calculated as a ratio between the number of ticks and the length of
  27 the procedure. The output is filled with blanks to ease readability.
  28
  29 .LP
  30 Available command line options are the following:
  31
  32 .TP
  33 .RB -m " mapfile"
  34 Specify a mapfile, which by default is
  35 .B /usr/src/linux/System.map.
  36 You should specify the map file on cmdline if your current kernel isn't the
  37 last one you compiled. If the name of the map file ends with `.gz' it
  38 is decompressed on the fly.
  39
  40 .TP
  41 .RB -p " pro-file"
  42 Specify a different profiling buffer, which by default is
  43 .B /proc/profile.
  44 Using a different pro-file is useful if you want to `freeze' the
  45 kernel profiling at some time and read it later. The
  46 .B /proc/profile
  47 file can be copied using `cat' or `cp'. There is no more support for
  48 compressed profile buffers, like in
  49 .B readprofile-1.1,
  50 because the program needs to know the size of the buffer in advance.
  51
  52 .TP
  53 .B -i
  54 Info. This makes
  55 .B readprofile
  56 only print the profiling step used by the kernel.
  57 The profiling step is the resolution of the profiling buffer, and
  58 is chosen during kernel configuration (through `make config'),
  59 or in the kernel's command line.
  60 If the
  61 .B -t
  62 (terse) switch is used together with
  63 .B -i
  64 only the decimal number is printed.
  65
  66 .TP
  67 .B -a
  68 Print all symbols in the mapfile. By default the procedures with 0 reported
  69 ticks are not printed.
  70
  71 .TP
  72 .B -r
  73 Reset the profiling buffer. This can only be invoked by root, because
  74 .B /proc/profile
  75 is readable by everybody but writable only by the superuser. However,
  76 you can make
  77 .B readprofile
  78 setuid 0, in order to reset the buffer without gaining privileges.
  79
  80 .TP
  81 .RB -M " multiplier"
  82 On some architectures it is possible to alter the frequency at which
  83 the kernel delivers profiling interrupts to each CPU.  This option allows you to
  84 set the frequency, as a multiplier of the system clock frequency, HZ.
  85 This is supported on i386-SMP (2.2 and 2.4 kernel) and also on sparc-SMP
  86 and sparc64-SMP (2.4 kernel).  This option also resets the profiling buffer,
  87 and requires superuser privileges.
  88
  89 .TP
  90 .B -v
  91 Verbose. The output is organized in four columns and filled with blanks.
  92 The first column is the RAM address of a kernel function, the second is
  93 the name of the function, the third is the number of clock ticks and the
  94 last is the normalized load.
  95
  96 .TP
  97 .B -V
  98 Version. This makes
  99 .B readprofile
 100 print its version number and exit.
 101
 102 .SH EXAMPLES
 103 Browse the profiling buffer ordering by clock ticks:
 104 .nf
 105    readprofile | sort -nr | less
 106
 107 .fi
 108 Print the 20 most loaded procedures:
 109 .nf
 110    readprofile | sort -nr +2 | head -20
 111
 112 .fi
 113 Print only filesystem profile:
 114 .nf
 115    readprofile | grep _ext2
 116
 117 .fi
 118 Look at all the kernel information, with ram addresses"
 119 .nf
 120    readprofile -av | less
 121
 122 .fi
 123 Browse a `freezed' profile buffer for a non current kernel:
 124 .nf
 125    readprofile -p ~/profile.freeze -m /zImage.map.gz
 126
 127 .fi
 128 Request profiling at 2kHz per CPU, and reset the profiling buffer
 129 .nf
 130    sudo readprofile -M 20
 131
 132 .fi
 133
 134 .SH BUGS
 135
 136 .LP
 137 .B readprofile
 138 only works with an 1.3.x or newer kernel,
 139 because
 140 .B /proc/profile
 141 changed in the step from 1.2 to 1.3
 142
 143 .LP
 144 This program only works with ELF kernels. The change for a.out kernels
 145 is trivial, and left as an exercise to the a.out user.
 146
 147 .LP
 148 To enable profiling, the kernel must be rebooted, because no profiling module
 149 is available, and it wouldn't be easy to build. To enable profiling,
 150 you can specify "profile=2" (or another number) on the kernel commandline.
 151 The number you specify is the two-exponent used as profiling step.
 152
 153 .LP
 154 Profiling is disabled when interrupts are inhibited. This means that many
 155 profiling ticks happen when interrupts are re-enabled. Watch out for
 156 misleading information.
 157
 158 .SH FILES
 159 .nf
 160 /proc/profile              A binary snapshot of the profiling buffer.
 161 /usr/src/linux/System.map  The symbol table for the kernel.
 162 /usr/src/linux/*           The program being profiled :-)
 163 .fi
 164