getrusage and the data type
are used to examine the resource usage of a process. They are declared
This function reports resource usage totals for processes specified by processes, storing the information in
In most systems, processes has only two valid values:
- Just the current process.
- All child processes (direct and indirect) that have already terminated.
The return value of
getrusageis zero for success, and
- The argument processes is not valid.
One way of getting resource usage for a particular child process is with
wait4, which returns totals for a child when it
terminates. See BSD Wait Functions.
This data type stores various resource usage statistics. It has the following members, and possibly others:
struct timeval ru_utime
- Time spent executing user instructions.
struct timeval ru_stime
- Time spent in operating system code on behalf of processes.
long int ru_maxrss
- The maximum resident set size used, in kilobytes. That is, the maximum number of kilobytes of physical memory that processes used simultaneously.
long int ru_ixrss
- An integral value expressed in kilobytes times ticks of execution, which indicates the amount of memory used by text that was shared with other processes.
long int ru_idrss
- An integral value expressed the same way, which is the amount of unshared memory used for data.
long int ru_isrss
- An integral value expressed the same way, which is the amount of unshared memory used for stack space.
long int ru_minflt
- The number of page faults which were serviced without requiring any I/O.
long int ru_majflt
- The number of page faults which were serviced by doing I/O.
long int ru_nswap
- The number of times processes was swapped entirely out of main memory.
long int ru_inblock
- The number of times the file system had to read from the disk on behalf of processes.
long int ru_oublock
- The number of times the file system had to write to the disk on behalf of processes.
long int ru_msgsnd
- Number of IPC messages sent.
long int ru_msgrcv
- Number of IPC messages received.
long int ru_nsignals
- Number of signals received.
long int ru_nvcsw
- The number of times processes voluntarily invoked a context switch (usually to wait for some service).
long int ru_nivcsw
- The number of times an involuntary context switch took place (because a time slice expired, or another process of higher priority was scheduled).
vtimes is a historical function that does some of what
getrusage is a better choice.
vtimes and its
vtimes data structure are declared in
vtimesreports resource usage totals for a process.
If current is non-null,
vtimesstores resource usage totals for the invoking process alone in the structure to which it points. If child is non-null,
vtimesstores resource usage totals for all past children (which have terminated) of the invoking process in the structure to which it points.— Data Type: struct vtimes
This data type contains information about the resource usage of a process. Each member corresponds to a member of the
struct rusagedata type described above.
- User CPU time. Analogous to
- System CPU time. Analogous to
- Data and stack memory. The sum of the values that would be reported as
- Shared memory. Analogous to
- Maximent resident set size. Analogous to
- Major page faults. Analogous to
- Minor page faults. Analogous to
- Swap count. Analogous to
- Disk reads. Analogous to
- Disk writes. Analogous to
The return value is zero if the function succeeds;
vtimes, is supported but not documented here. It is declared in sys/vtimes.h.