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Top Forums Programming wait4 Post 302292228 by otheus on Friday 27th of February 2009 07:37:48 AM
Old 02-27-2009
I get the same most of the time, but if you look carefully, you will occasionally get a process that actually used user time. Grep the output like this: "prog | grep -v 00000$".

Also, note that by not exiting or returning after the printf, you create a "fork bomb". Your process will run endlessly, forking processes on end.

Why the exec takes so little user-time? Because you're making exactly one library function call as a user, which calls the system exec() call, which from at that point belongs to the system time.
 

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what is diff b/w wait3() and wait4() system call

helo, i read man pages but still confuse about wait3() and wait4() stystem call what is exact diff b/w wait3() and wait4() system call and what is diff b/w waitpid() and wait3() and wait4() Regards, Amit (1 Reply)
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serialize(2)							System Calls Manual						      serialize(2)

NAME
serialize() - force target process to run serially with other processes SYNOPSIS
DESCRIPTION
The system call is used to force the target process referenced by the pid value passed in to run serially with other processes also marked for serialization. If the value of pid is zero, then the currently running process is marked for serialization. Once a process has been marked by the process stays marked until process completion, unless is reissued on the serialized process with timeshare set to 1. If timeshare is set to 1, the process specified in pid will be returned to normal timeshare scheduling algorithms. This call is used to improve process throughput since process throughput usually increases for large processes when they are executed seri- ally instead of allowing each program to run for only a short period of time. By running large processes one at a time, the system makes more efficient use of the CPU as well as system memory, since each process does not end up constantly faulting in its working set, to only have the pages stolen when another process starts running. As long as there is enough memory in the system, processes marked by behave no differently from other processes in the system. However, once memory becomes tight, processes marked by are run one at a time with the highest priority processes being run first. Each process runs for a finite interval of time before another serialized process is allowed to run. RETURN VALUE
returns zero upon successful completion, or nonzero if the system call failed. ERRORS
If fails, it sets (see errno(2)) to the following value: The pid passed in does not exist. WARNINGS
The user has no way of forcing an execution order on serialized processes. AUTHOR
was developed by HP. SEE ALSO
serialize(1), privileges(5). serialize(2)
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