Next: Limits on Resources, Up: Resource Usage And Limitation
The function getrusage and the data type struct rusage
are used to examine the resource usage of a process. They are declared
in sys/resource.h.
This function reports resource usage totals for processes specified by processes, storing the information in
*rusage.In most systems, processes has only two valid values:
RUSAGE_SELF- Just the current process.
RUSAGE_CHILDREN- All child processes (direct and indirect) that have already terminated.
In the GNU system, you can also inquire about a particular child process by specifying its process ID.
The return value of
getrusageis zero for success, and-1for failure.
EINVAL- The argument processes is not valid.
One way of getting resource usage for a particular child process is with
the function 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 does. getrusage is a better choice.
vtimes and its vtimes data structure are declared in
sys/vtimes.h.
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.
vm_utime- User CPU time. Analogous to
ru_utimeinstruct rusagevm_stime- System CPU time. Analogous to
ru_stimeinstruct rusagevm_idsrss- Data and stack memory. The sum of the values that would be reported as
ru_idrssandru_isrssinstruct rusagevm_ixrss- Shared memory. Analogous to
ru_ixrssinstruct rusagevm_maxrss- Maximent resident set size. Analogous to
ru_maxrssinstruct rusagevm_majflt- Major page faults. Analogous to
ru_majfltinstruct rusagevm_minflt- Minor page faults. Analogous to
ru_minfltinstruct rusagevm_nswap- Swap count. Analogous to
ru_nswapinstruct rusagevm_inblk- Disk reads. Analogous to
ru_inblkinstruct rusagevm_oublk- Disk writes. Analogous to
ru_oublkinstruct rusageThe return value is zero if the function succeeds;
-1otherwise.
vtimes, is supported but not documented here. It is declared in
sys/vtimes.h.