NAME
getrusage —
get information about
resource utilization
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/resource.h>
#define RUSAGE_SELF 0
#define RUSAGE_CHILDREN -1
int
getrusage(
int
who,
struct rusage
*rusage);
DESCRIPTION
getrusage() returns information describing the resources used
by the current process, or all its terminated child processes. The
who parameter 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 used (in kilobytes).
-
-
- ru_ixrss
- 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.
-
-
- 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
activity.
-
-
- 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.
NOTES
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.
ERRORS
getrusage() returns -1 on error. The possible errors are:
-
-
- [
EINVAL
]
- The who parameter is not a valid
value.
-
-
- [
EFAULT
]
- The address specified by the rusage
parameter is not in a valid part of the process address space.
SEE ALSO
gettimeofday(2),
wait(2)
HISTORY
The
getrusage() function call appeared in
4.2BSD.
BUGS
There is no way to obtain information about a child process that has not yet
terminated.