GETRUSAGE(2) System Calls Manual GETRUSAGE(2)
NAME
getrusageget information about resource utilization
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/resource.h>
#define RUSAGE_SELF 0
#define RUSAGE_CHILDREN -1
int
getrusage(int who, struct rusage *rusage);
DESCRIPTION
getrusage() returns information describing the resources used 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; /* 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 used (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.
ERRORS
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.
SEE ALSO
HISTORY
The getrusage() function call appeared in 4.2BSD.
BUGS
There is no way to obtain information about a child process that has not yet terminated.