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GETRUSAGE(2) System Calls Manual GETRUSAGE(2)

NAME

getrusageget information about resource utilization

SYNOPSIS

#include <sys/resource.h>
int
getrusage(int who, struct rusage *rusage);

DESCRIPTION

getrusage() returns resource usage information for argument who, which can be one of the following:
 
 
RUSAGE_SELF
Resources used by the current process.
 
 
RUSAGE_CHILDREN
Resources used by all the terminated children of the current process.
 
 
RUSAGE_THREAD
Resources used by the current thread.
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 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-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.

RETURN VALUES

Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

ERRORS

getrusage() will fail if:
 
 
[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

clock_gettime(2), gettimeofday(2), wait(2)

STANDARDS

The getrusage() function conforms to IEEE Std 1003.1-2008 (“POSIX.1”).
The RUSAGE_THREAD flag is an extension to that specification.

HISTORY

A predecessor to getrusage(), times(), first appeared in Version 3 AT&T UNIX. The getrusage() system call first appeared in 4.1cBSD.
The RUSAGE_THREAD flag has been available since OpenBSD 4.8.

BUGS

There is no way to obtain information about a child process that has not yet terminated.
February 28, 2015 OpenBSD-6.1