GETRUSAGE(2)
HOME ||
NAME
LIBRARY
SYNOPSIS
DESCRIPTION
NOTES
RETURN VALUES
ERRORS
SEE ALSO
BUGS
HISTORY
getrusage -- get information about resource utilization
Standard C Library (libc, -lc)
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#define RUSAGE_SELF 0
#define RUSAGE_CHILDREN -1
int
getrusage(int who, struct rusage *rusage);
The getrusage() system call returns information describing the resources
utilized by the current process, or all its terminated child processes.
The who argument is either RUSAGE_SELF or RUSAGE_CHILDREN. The buffer to
which rusage 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; /* 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:
ru_utime the total amount of time spent executing in user mode.
ru_stime the total amount of time spent in the system executing on
behalf of the process(es).
ru_maxrss the maximum resident set size utilized (in kilobytes).
ru_ixrss an ``integral'' value indicating the amount of memory used
by the text segment that was also shared among other pro-
cesses. This value is expressed in units of kilobytes *
ticks-of-execution. Ticks are statistics clock ticks. The
statistics clock has a frequency of sysconf(_SC_CLK_TCK)
ticks per second.
ru_idrss 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).
ru_isrss 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).
ru_minflt 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.
ru_majflt the number of page faults serviced that required I/O activ-
ity.
ru_nswap the number of times a process was ``swapped'' out of main
memory.
ru_inblock the number of times the file system had to perform input.
ru_oublock the number of times the file system had to perform output.
ru_msgsnd the number of IPC messages sent.
ru_msgrcv the number of IPC messages received.
ru_nsignals the number of signals delivered.
ru_nvcsw 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).
ru_nivcsw 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 ru_inblock and ru_oublock 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.
The getrusage() function returns the value 0 if successful; otherwise the
value -1 is returned and the global variable errno is set to indicate the
error.
The getrusage() system call will fail if:
[EINVAL] The who argument is not a valid value.
[EFAULT] The address specified by the rusage argument is not in
a valid part of the process address space.
gettimeofday(2), wait(2), clocks(7)
There is no way to obtain information about a child process that has not
yet terminated.
The getrusage() system call appeared in 4.2BSD.