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diff --git a/sys-utils/readprofile.8 b/sys-utils/readprofile.8 new file mode 100644 index 0000000..b987abb --- /dev/null +++ b/sys-utils/readprofile.8 @@ -0,0 +1,151 @@ +.TH READPROFILE "8" "October 2011" "util-linux" "System Administration" +.SH NAME +readprofile \- read kernel profiling information +.SH SYNOPSIS +.B readprofile +[options] +.SH VERSION +This manpage documents version 2.0 of the program. +.SH DESCRIPTION +The +.B readprofile +command uses the +.I /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. +.SH OPTIONS +.TP +\fB\-a\fR, \fB\-\-all\fR +Print all symbols in the mapfile. By default the procedures with +reported ticks are not printed. +.TP +\fB\-b\fR, \fB\-\-histbin\fR +Print individual histogram-bin counts. +.TP +\fB\-i\fR, \fB\-\-info\fR +Info. This makes +.B 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 +.B \-t +(terse) switch is used together with +.B \-i +only the decimal number is printed. +.TP +\fB\-m\fR, \fB\-\-mapfile\fR \fImapfile\fR +Specify a mapfile, which by default is +.IR /usr/src/linux/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. +.TP +\fB\-M\fR, \fB\-\-multiplier\fR \fImultiplier\fR +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. +.TP +\fB\-p\fR, \fB\-\-profile\fR \fIpro-file\fR +Specify a different profiling buffer, which by default is +.IR /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 +.I /proc/profile +file can be copied using `cat' or `cp'. There is no more support for +compressed profile buffers, like in +.B readprofile-1.1, +because the program needs to know the size of the buffer in advance. +.TP +\fB\-r\fR, \fB\-\-reset\fR +Reset the profiling buffer. This can only be invoked by root, +because +.I /proc/profile +is readable by everybody but writable only by the superuser. +However, you can make +.B readprofile +set-user-ID 0, in order to reset the buffer without gaining privileges. +.TP +\fB\-s, \fB\-\-counters\fR +Print individual counters within functions. +.TP +\fB\-v\fR, \fB\-\-verbose\fR +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. +.TP +\fB\-V\fR, \fB\-\-version\fR +Display version information and exit. +.TP +\fB\-h\fR, \fB\-\-help\fR +Display help text and exit. +.SH FILES +.nf +/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 :-) +.fi +.SH BUGS +.B readprofile +only works with a 1.3.x or newer kernel, because +.I /proc/profile +changed in the step from 1.2 to 1.3 +.LP +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. +.LP +To enable profiling, the kernel must be rebooted, because no +profiling module is available, and it wouldn't be easy to build. To +enable profiling, you can specify "profile=2" (or another number) on +the kernel commandline. The number you specify is the two-exponent +used as profiling step. +.LP +Profiling is disabled when interrupts are inhibited. This means that +many profiling ticks happen when interrupts are re-enabled. Watch +out for misleading information. +.SH EXAMPLE +Browse the profiling buffer ordering by clock ticks: +.nf + readprofile | sort \-nr | less + +.fi +Print the 20 most loaded procedures: +.nf + readprofile | sort \-nr +2 | head \-20 + +.fi +Print only filesystem profile: +.nf + readprofile | grep _ext2 + +.fi +Look at all the kernel information, with ram addresses: +.nf + readprofile \-av | less + +.fi +Browse a `frozen' profile buffer for a non current kernel: +.nf + readprofile \-p ~/profile.freeze \-m /zImage.map.gz + +.fi +Request profiling at 2kHz per CPU, and reset the profiling buffer: +.nf + sudo readprofile \-M 20 +.fi +.SH AVAILABILITY +The readprofile command is part of the util-linux package and is +available from +.UR https://\:www.kernel.org\:/pub\:/linux\:/utils\:/util-linux/ +Linux Kernel Archive +.UE . |