readprofile
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NAME
readprofile - a tool to read kernel profiling information
SYNOPSIS
readprofile [ options ]
VERSION
This manpage documents version 1.1 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 thicks and the lenght of the
procedure. The output is filled with blanks to ease read-
ability.
Available command line options are the following:
-m mapfile
Specify a mapfile, which by default is
/usr/src/linux/System.map. To ease use of readpro-
file with kernels in the 1.1.7x series, if the
default file can't be opened, the alternate file
/usr/src/linux/zSystem.map is tried. You should
specify the map file on cmdline if your current
kernel isn't the last one you compiled. 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'. If the name of the pro-file ends by `.gz' it
is decompressed on the fly. The pro-file is such
that gzip shrinks it by 50-100 times.
-i Info. This makes readprofile only print the profil-
ing step used by the kernel. The profiling step is
the resolution of the profiling buffer, and is cho-
sen during kernel configuration (through `make con-
fig'). 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.
-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.
-t Terse. This causes the output to be unfilled. It is
the format used in the first release of readpro-
file.
-v 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.
-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 gzipped `freezed' profile buffer for a non cur-
rent kernel:
readprofile -p ~/profile.freeze.gz -m /zImage.map
BUGS
readprofile needs a kernel version 1.1.73 or newer,
because /proc/profile is absent in older versions.
To enable profiling, the kernel must be reconfigured,
recompiled, and rebooted. No profiling module is
available, and it wouldn't be easy to build. So this can
be construed as a feature.
Profiling is disabled when interrupts are inhibited. This
means that many profiling ticks happen when interrupts are
re-enabled. Watch out for misleading information.
AUTHOR
Readprofile and /proc/profile are by Alessandro Rubini
(rubini@ipvvis.unipv.it)
FILES
/proc/profile A binary snapshot of the profiling buffer.
/usr/src/linux/System.map The symbol table for the kernel.
/usr/src/linux/zSystem.map Old name for the symbol table.
/usr/src/linux/* The program being profiled :-)
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