GETRUSAGE(2) Linux Programmer s Manual GETRUSAGE(2)

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 statis- tics will include the resources used by grandchildren, and fur- ther 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.

NOTES Including <sys/time.h> is not required these days, but increases porta- bility. (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 automat- ically included in the value returned by RUSAGE_CHILDREN, although POSIX.1-2001 explicitly prohibits this. This non-conformance is recti- fied in Linux 2.6.9 and later.

The above struct was taken from 4.3BSD Reno. Not all fields are mean- ingful 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.

SEE ALSO getrlimit(2), times(2), wait(2), wait4(2)

Linux 2.6.9 2004-11-16 GETRUSAGE(2)