NAME
getrusage - get resource usage
SYNOPSIS
#include <sys/time.h>
#include <sys/resource.h>
int getrusage(int who, struct rusage *usage);
DESCRIPTION
getrusage() returns resource usage measures for who, which can be one
of the following:
RUSAGE_SELF
Return resource usage statistics for the calling process, which
is the sum of resources used by all threads in the process.
RUSAGE_CHILDREN
Return resource usage statistics for all children of the calling
process that have terminated and been waited for. These
statistics will include the resources used by grandchildren, and
further removed descendants, if all of the intervening
descendants waited on their terminated children.
RUSAGE_THREAD (since Linux 2.6.26)
Return resource usage statistics for the calling thread.
The resource usages are returned in the structure pointed to by usage,
which has the following form:
struct rusage {
struct timeval ru_utime; /* user time used */
struct timeval ru_stime; /* system time used */
long ru_maxrss; /* maximum resident set size */
long ru_ixrss; /* integral shared 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 */
};
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is
set appropriately.
ERRORS
EFAULT usage points outside the accessible address space.
EINVAL who is invalid.
CONFORMING TO
SVr4, 4.3BSD. POSIX.1-2001 specifies getrusage(), but only specifies
the fields ru_utime and ru_stime.
RUSAGE_THREAD is Linux-specific.
NOTES
Resource usage metrics are preserved across an execve(2).
Including <sys/time.h> is not required these days, but increases
portability. (Indeed, struct timeval is defined in <sys/time.h>.)
In Linux kernel versions before 2.6.9, if the disposition of SIGCHLD is
set to SIG_IGN then the resource usages of child processes are
automatically included in the value returned by RUSAGE_CHILDREN,
although POSIX.1-2001 explicitly prohibits this. This nonconformance
is rectified in Linux 2.6.9 and later.
The structure definition shown at the start of this page was taken from
4.3BSD Reno. Not all fields are meaningful under Linux. In Linux 2.4
only the fields ru_utime, ru_stime, ru_minflt, and ru_majflt are
maintained. Since Linux 2.6, ru_nvcsw and ru_nivcsw are also
maintained. Since Linux 2.6.22, ru_inblock and ru_oublock are also
maintained.
See also the description of /proc/PID/stat in proc(5).
SEE ALSO
clock_gettime(2), getrlimit(2), times(2), wait(2), wait4(2), clock(3)
COLOPHON
This page is part of release 3.24 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/.