11-14-2013
The implementation of time may be OS depdendent. But the basic operation is similar on all platforms.
1. Create the command + arguments as a child process
2. wait until the child process completes
3. Call getrusage() for all of the children and display the time consumed - systems are not required to call getrusage(). They may use a feature like the /proc filesystem.
The wall time is how long it took the child (plus its children if any) to complete.
The "sys" component is the sum of kernel time for children.
The "user" component is the sum of user mode execution time for children.
Wall time does not usually add up to sys + user for longer running processes. Why? I/O disk waits, cpu waits, and multiple threads/children all subtract or add to wall time relative to sys + user.
10 More Discussions You Might Find Interesting
1. UNIX for Advanced & Expert Users
hello
is there any implementation of msopf and pim protocoles in unix?
:confused: (1 Reply)
Discussion started by: jalil smail
1 Replies
2. UNIX for Advanced & Expert Users
It is possible for me to obtain the Inode of the path name using
ls -i <pathname> command
Can anyone tell me how its implemented... (3 Replies)
Discussion started by: ganapathy.psgit
3 Replies
3. UNIX for Advanced & Expert Users
hey i have to implement copy command in parallel in c language.
i dont know how to create a new directory in destination.
if anything u know related to this help me (1 Reply)
Discussion started by: rajsekhar28
1 Replies
4. UNIX for Advanced & Expert Users
Hi experts,
It would be grateful if you can guide me on the following,
1.How to find the time of excution of a particular unix command.
2. How to find the terminal (IP Address) from where that particular unix command was excuted.
3. How to find the user who executed that particular unix... (1 Reply)
Discussion started by: apsprabhu
1 Replies
5. UNIX for Dummies Questions & Answers
Hi all,
I just downloaded this example from the net. I was looking around for a hash table like implementation in unix when I came across this.
ARRAY=( "cow:moo"
"dinosaur:roar"
"bird:chirp"
"bash:rock" )
for animal in ${ARRAY} ; do
KEY=${animal%%:*}
... (8 Replies)
Discussion started by: anindyabecs
8 Replies
6. Shell Programming and Scripting
Hello.
I use time in order to calculate the execution time of a program.
The output format is:
real 0m0.059s
user 0m0.028s
sys 0m0.004s
Is there a simple and elegant way to add user and sys together, and convert to milliseconds?
Thanks a lot! (4 Replies)
Discussion started by: dynelight
4 Replies
7. Linux
Hi,
I am trying to execute a program with pipes to run a few basic commands by forking children. When I try to run commands in the child process without pipe, I am unable to run the command as execv fails. However for commands that are given with pipes execute successfully.
for example:... (1 Reply)
Discussion started by: mmurali2
1 Replies
8. UNIX for Dummies Questions & Answers
So we know that Unix is free source software. And we know that Unix have support for FAT 16 and FAT 32. Does anyone know where can I found that implementation in code ?
Thank you. (2 Replies)
Discussion started by: medolina
2 Replies
9. Shell Programming and Scripting
Hello All
I have request below. Please Help
Below is the input.
mrkInternetMedicalSpecialtyAlt=<order>0</order>
<code>PED</code>
Need Output as below
mrkInternetMedicalSpecialtyAlt=<order>0</order><code>PED</code>
Value "PED" is not always same.
Please use correct CODE tags... (6 Replies)
Discussion started by: srilu
6 Replies
10. UNIX for Advanced & Expert Users
I have a running service which runs in background.
It execute shell commands by function system(cmd)
I need to report fail when command execution takes more than 60 seconds.
Parent doesn't need to wait for 60 seconds of time if the cmd execution completed already.
runCommand()
{
pid_t... (3 Replies)
Discussion started by: techmonk
3 Replies
WAIT4(2) Linux Programmer's Manual WAIT4(2)
NAME
wait3, wait4 - wait for process to change state, BSD style
SYNOPSIS
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>
pid_t wait3(int *status, int options,
struct rusage *rusage);
pid_t wait4(pid_t pid, int *status, int options,
struct rusage *rusage);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
wait3():
_BSD_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
wait4():
_BSD_SOURCE
DESCRIPTION
The wait3() and wait4() system calls are similar to waitpid(2), but additionally return resource usage information about the child in the
structure pointed to by rusage.
Other than the use of the rusage argument, the following wait3() call:
wait3(status, options, rusage);
is equivalent to:
waitpid(-1, status, options);
Similarly, the following wait4() call:
wait4(pid, status, options, rusage);
is equivalent to:
waitpid(pid, status, options);
In other words, wait3() waits of any child, while wait4() can be used to select a specific child, or children, on which to wait. See
wait(2) for further details.
If rusage is not NULL, the struct rusage to which it points will be filled with accounting information about the child. See getrusage(2)
for details.
RETURN VALUE
As for waitpid(2).
ERRORS
As for waitpid(2).
CONFORMING TO
4.3BSD.
NOTES
Including <sys/time.h> is not required these days, but increases portability. (Indeed, <sys/resource.h> defines the rusage structure with
fields of type struct timeval defined in <sys/time.h>.)
On Linux, wait3() is a library function implemented on top of the wait4() system call.
SEE ALSO
fork(2), getrusage(2), sigaction(2), signal(2), wait(2), signal(7)
COLOPHON
This page is part of release 3.27 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 2010-09-20 WAIT4(2)