Mac OS X / Darwin man pages : getrusage (2)
getrusage (2)
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getrusage - get information about resource utilization
#include <sys/time.h>
#include <sys/resource.h>
#define RUSAGE_SELF 0
#define RUSAGE_CHILDREN -1
int
getrusage(int who, struct rusage *rusage);
Getrusage() returns information describing the resources utilized 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;
- /* integral 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 utilized (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-ofexecution.
- 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.
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.
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.
gettimeofday(2)
, wait(2)
There is no way to obtain information about a child process that has not
yet terminated.
The getrusage() function call appeared in 4.2BSD.
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