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FreeBSD 11.0 - man page for getrusage (freebsd section 2)

GETRUSAGE(2)						      BSD System Calls Manual						      GETRUSAGE(2)

NAME
getrusage -- get information about resource utilization
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/types.h> #include <sys/time.h> #include <sys/resource.h> #define RUSAGE_SELF 0 #define RUSAGE_CHILDREN -1 #define RUSAGE_THREAD 1 int getrusage(int who, struct rusage *rusage);
DESCRIPTION
The getrusage() system call returns information describing the resources utilized by the current thread, the current process, or all its ter- minated child processes. The who argument is either RUSAGE_THREAD, 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 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. Ticks are statistics clock ticks. The statistics clock has a frequency of sysconf(_SC_CLK_TCK) ticks per second. 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
The getrusage() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indi- cate the error.
ERRORS
The getrusage() system call will fail if: [EINVAL] The who argument is not a valid value. [EFAULT] The address specified by the rusage argument is not in a valid part of the process address space.
SEE ALSO
gettimeofday(2), wait(2), clocks(7)
HISTORY
The getrusage() system call appeared in 4.2BSD. The RUSAGE_THREAD facility first appeared in FreeBSD 8.1.
BUGS
There is no way to obtain information about a child process that has not yet terminated.
BSD
May 1, 2010 BSD