LinuxAsmTools
asmtimer - time program execution
SYNOPSIS
asmtimer <executable file>
if the <executable file> is omitted, a file
browser will allow selection of file.
DESCRIPTION
asmtimer executes a file a specified number of
times. Each execution is timed using data supplied
by the kernel and by manually recording start and
stop times. All these time are collected and
averages computed. The results are displayed.
the program being timed is most accurate if
no keyboard waits (key pressing) are required
and program output is piped to a file.
also, it helps to run the timer several times
in quick secession to get a sampling of times.
Linux is a difficult system to get accurate
timing information without patching the kernel
and writing special programs. Asmtimer tries
to solve this problem by using averages and
repeated executions. It appears to be useful
for comparing programs.
OPERATION
asmTimer reads the system time before executing a
program and again after it completes. This time
is saved in an array for each time a program is
timed. Also information from the kernel is collected
and stored in the same array.
the timed program is executed in a shell (such as bash)
and the time to load the shell is included. The shell
load time can be calculated and subtracted out if
necessary, see hints.
after all timing runs have been completed the averages
are computed and the array sorted. Information from
the array is then displayed.
to remove the load times for a shell or the program
being timed, it is necessary to determine times and
subtract them out. To find a shells load time, run
it and divide by two. Essentially, we are calling
the shell to run the shell and then exit.
to get more accurate timing it helps to do 8 or more
timing runs. Eventually, the program will run with
little interference from the kernel and we will have
a more accurate timing. This does not work as well
for programs that take seconds or even minutes, but
it does get close to the real time.
it is possible to use shell commands to time programs.
for example in bash type:
time ls > any_file
The output appears to be kernel information and
somewhat confusing.
AUTHOR
Jeff Owens <jko@bsn1.net>
COPYRIGHT
Copyright (C) 2007 Jeff Owens
This program comes with absolutely NO WARRANTY
