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returns
information describing the resources utilized by the current process, or
all its terminated child processes. The parameter is either or The buffer
to which points will be filled in with the following structure: struct
rusage { struct timeval ru_utime; /* user time used */
struct timeval ru_stime; /* system time used */
long ru_maxrss; /* integral max resident set size */
long ru_ixrss; /* integral shared text memory size */
long ru_idrss; /* integral unshared data size */
long ru_isrss; /* integral unshared stack size */
long ru_minflt; /* page reclaims */
long ru_majflt; /* page faults */
long ru_nswap; /* swaps */
long ru_inblock; /* block input operations */
long ru_oublock; /* block output operations */
long ru_msgsnd; /* messages sent */
long ru_msgrcv; /* messages received */
long ru_nsignals; /* signals received */
long ru_nvcsw; /* voluntary context switches */
long ru_nivcsw; /* involuntary context switches */
}; The fields are interpreted as follows: the total amount of time
spent executing in user mode. the total amount of time spent in the system
executing on behalf of the process(es). the maximum resident set size utilized
(in kilobytes). an ‘integral’ value indicating the amount of memory used
by the text segment that was also shared among other processes. This value
is expressed in units of kilobytes * ticks-of-execution. an integral value
of the amount of unshared memory residing in the data segment of a process
(expressed in units of kilobytes * ticks-of-execution). an integral value
of the amount of unshared memory residing in the stack segment of a process
(expressed in units of kilobytes * ticks-of-execution). the number of page
faults serviced without any I/O activity; here I/O activity is avoided
by ‘reclaiming’ a page frame from the list of pages awaiting reallocation.
the number of page faults serviced that required I/O activity. the number
of times a process was ‘swapped’ out of main memory. the number of times
the file system had to perform input. the number of times the file system
had to perform output. the number of IPC messages sent. the number of IPC
messages received. the number of signals delivered. the number of times
a context switch resulted due to a process voluntarily giving up the processor
before its time slice was completed (usually to await availability of a
resource). the number of times a context switch resulted due to a higher
priority process becoming runnable or because the current process exceeded
its time slice.
The numbers and account only for real I/O; data
supplied by the caching mechanism is charged only to the first process
to read or write the data.
returns -1 on error. The possible errors
are: The parameter is not a valid value. The address specified by the
parameter is not in a valid part of the process address space.
There is no way to obtain information about a child process that has
not yet terminated.
The function call appeared in
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