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1 perry 1 READPROFILE
2 !!!READPROFILE
3 NAME
4 SYNOPSIS
5 VERSION
6 DESCRIPTION
7 EXAMPLES
8 BUGS
9 FILES
10 ----
11 !!NAME
12
13
14 readprofile - a tool to read kernel profiling information
15 !!SYNOPSIS
16
17
18 __readprofile__ [[ ''options'' ]
19 !!VERSION
20
21
22 This manpage documents version 2.0 of the
23 program.
24 !!DESCRIPTION
25
26
27 The __readprofile__ command uses the __/proc/profile__
28 information to print ascii data on standard output. The
29 output is organized in three columns: the first is the
30 number of clock ticks, the second is the name of the C
31 function in the kernel where those many ticks occurred, and
32 the third is the normalized `load' of the procedure,
33 calculated as a ratio between the number of ticks and the
34 length of the procedure. The output is filled with blanks to
35 ease readability.
36
37
38 Available command line options are the
39 following:
40
41
42 -m __mapfile__
43
44
45 Specify a mapfile, which by default is
46 __/usr/src/linux/System.map.__ You should specify the map
47 file on cmdline if your current kernel isn't the last one
48 you compiled. If the name of the map file ends with `.gz' it
49 is decompressed on the fly.
50
51
52 -p __pro-file__
53
54
55 Specify a different profiling buffer, which by default is
56 __/proc/profile.__ Using a different pro-file is useful
57 if you want to `freeze' the kernel profiling at some time
58 and read it later. The __/proc/profile__ file can be
59 copied using `cat' or `cp'. There is no more support for
60 compressed profile buffers, like in __readprofile-1.1,__
61 because the program needs to know the size of the buffer in
62 advance.
63
64
65 __-i__
66
67
68 Info. This makes __readprofile__ only print the profiling
69 step used by the kernel. The profiling step is the
70 resolution of the profiling buffer, and is chosen during
71 kernel configuration (through `make config'), or in the
72 kernel's command line. If the __-t__ (terse) switch is
73 used together with __-i__ only the decimal number is
74 printed.
75
76
77 __-a__
78
79
80 Print all symbols in the mapfile. By default the procedures
81 with 0 reported ticks are not printed.
82
83
84 __-r__
85
86
87 Reset the profiling buffer. This can only be invoked by
88 root, because __/proc/profile__ is readable by everybody
89 but writable only by the superuser. However, you can make
90 __readprofile__ setuid 0, in order to reset the buffer
91 without gaining privileges.
92
93
94 -M __multiplier__
95
96
97 On some architectures it is possible to alter the frequency
98 at which the kernel delivers profiling interrupts to each
99 CPU. This option allows you to set the frequency, as a
100 multiplier of the system clock frequency, HZ. This is
101 supported on i386-SMP (2.2 and 2.4 kernel) and also on
102 sparc-SMP and sparc64-SMP (2.4 kernel). This option also
103 resets the profiling buffer, and requires superuser
104 privileges.
105
106
107 __-v__
108
109
110 Verbose. The output is organized in four columns and filled
111 with blanks. The first column is the RAM address of a kernel
112 function, the second is the name of the function, the third
113 is the number of clock ticks and the last is the normalized
114 load.
115
116
117 __-V__
118
119
120 Version. This makes __readprofile__ print its version
121 number and exit.
122 !!EXAMPLES
123
124
125 Browse the profiling buffer ordering by clock
126 ticks:
127
128
129 readprofile | sort -nr | less
130 Print the 20 most loaded procedures:
131
132
133 readprofile | sort -nr +2 | head -20
134 Print only filesystem profile:
135
136
137 readprofile | grep _ext2
138 Look at all the kernel information, with ram addresses
139
140
141 readprofile -av | less
142 Browse a `freezed' profile buffer for a non current kernel:
143
144
145 readprofile -p ~/profile.freeze -m /zImage.map.gz
146 Request profiling at 2kHz per CPU, and reset the profiling buffer
147
148
149 sudo readprofile -M 20
150 !!BUGS
151
152
153 __readprofile__ only works with an 1.3.x or newer kernel,
154 because __/proc/profile__ changed in the step from 1.2 to
155 1.3
156
157
158 This program only works with ELF kernels. The change for
159 a.out kernels is trivial, and left as an exercise to the
160 a.out user.
161
162
163 To enable profiling, the kernel must be rebooted, because no
164 profiling module is available, and it wouldn't be easy to
165 build. To enable profiling, you can specify
166
167
168 Profiling is disabled when interrupts are inhibited. This
169 means that many profiling ticks happen when interrupts are
170 re-enabled. Watch out for misleading
171 information.
172 !!FILES
173
174
175 /proc/profile A binary snapshot of the profiling buffer.
176 /usr/src/linux/System.map The symbol table for the kernel.
177 /usr/src/linux/* The program being profiled :-)
178 ----
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