freebsd-skq/lib/libc/sys/getrusage.2

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.\"     @(#)getrusage.2	8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.Dd June 4, 1993
.Dt GETRUSAGE 2
.Os
.Sh NAME
.Nm getrusage
.Nd get information about resource utilization
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/types.h
.In sys/time.h
.In sys/resource.h
.Fd "#define	RUSAGE_SELF	 0"
.Fd "#define	RUSAGE_CHILDREN	-1"
.Ft int
.Fn getrusage "int who" "struct rusage *rusage"
.Sh DESCRIPTION
The
.Fn getrusage
system call
returns information describing the resources utilized by the current
process, or all its terminated child processes.
The
.Fa who
argument is either
.Dv RUSAGE_SELF
or
.Dv RUSAGE_CHILDREN .
The buffer to which
.Fa rusage
points will be filled in with
the following structure:
.Bd -literal
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 */
};
.Ed
.Pp
The fields are interpreted as follows:
.Bl -tag -width ru_minfltaa
.It Fa ru_utime
the total amount of time spent executing in user mode.
.It Fa ru_stime
the total amount of time spent in the system executing on behalf
of the process(es).
.It Fa ru_maxrss
the maximum resident set size utilized (in kilobytes).
.It Fa ru_ixrss
an
.Dq 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
.Fn sysconf _SC_CLK_TCK
ticks per second.
.It Fa 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).
.It Fa 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).
.It Fa ru_minflt
the number of page faults serviced without any I/O activity; here
I/O activity is avoided by
.Dq reclaiming
a page frame from
the list of pages awaiting reallocation.
.It Fa ru_majflt
the number of page faults serviced that required I/O activity.
.It Fa ru_nswap
the number of times a process was
.Dq swapped
out of main
memory.
.It Fa ru_inblock
the number of times the file system had to perform input.
.It Fa ru_oublock
the number of times the file system had to perform output.
.It Fa ru_msgsnd
the number of IPC messages sent.
.It Fa ru_msgrcv
the number of IPC messages received.
.It Fa ru_nsignals
the number of signals delivered.
.It Fa 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).
.It Fa 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.
.El
.Sh NOTES
The numbers
.Fa ru_inblock
and
.Fa 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.
.Sh RETURN VALUES
.Rv -std getrusage
.Sh ERRORS
The
.Fn getrusage
system call will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa who
argument is not a valid value.
.It Bq Er EFAULT
The address specified by the
.Fa rusage
argument is not in a valid part of the process address space.
.El
.Sh SEE ALSO
.Xr gettimeofday 2 ,
.Xr wait 2 ,
.Xr clocks 7
.Sh HISTORY
The
.Fn getrusage
system call appeared in
.Bx 4.2 .
.Sh BUGS
There is no way to obtain information about a child process
that has not yet terminated.