getrusage(2) System Calls Manual getrusage(2)
Name
getrusage - get information about resource utilization
Syntax
#include <sys/time.h>
#include <sys/resource.h>
#define RUSAGE_SELF 0 /* calling process */
#define RUSAGE_CHILDREN -1 /* terminated child processes */
getrusage(who, rusage)
int who;
struct rusage *rusage;
Description
The system call returns information describing the resources utilized by the current process or all its terminated child processes. The
who parameter is one of RUSAGE_SELF and RUSAGE_CHILDREN. If rusage is nonzero, the buffer it points to will be filled in with the follow-
ing structure:
struct rusage {
struct timeval ru_utime; /* user time used */
struct timeval ru_stime; /* system time used */
int ru_maxrss;
int ru_ixrss; /* integral shared text size */
int ru_ismrss /* integral shared memory size */
int ru_idrss; /* integral unshared data size */
int ru_isrss; /* integral unshared stack size */
int ru_minflt; /* page reclaims */
int ru_majflt; /* page faults */
int ru_nswap; /* swaps */
int ru_inblock; /* block input operations */
int ru_oublock; /* block output operations */
int ru_msgsnd; /* messages sent */
int ru_msgrcv; /* messages received */
int ru_nsignals; /* signals received */
int ru_nvcsw; /* voluntary context switches */
int 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 processes.
ru_maxrss
The maximum resident set size utilized (in bytes).
ru_ixrss
An "integral" value indicating the amount of text memory used that was also shared among other processes. This value is expressed
in units of kilobytes * seconds-of-execution and is calculated by summing the number of shared memory pages in use each time the
internal system clock ticks and then averaging over 1-second intervals.
ru_ismrss
An integral value of the amount of shared memory residing in the data segment of a process (expressed in units of kilobytes * sec-
onds-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 * sec-
onds-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 *
seconds-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 com-
pleted, 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 cacheing mechanism is charged only to the first
process to read or write the data.
Restrictions
There is no way to obtain information about a child process that has not yet terminated.
Diagnostics
The call fails under the following conditions:
[EINVAL] The who parameter is not a valid value on RUSAGE_SELF or RUSAGE_CHILDREN.
[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)
getrusage(2)