getrusage.2

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 2 代码 · 共 162 行

.\" SCCSID: @(#)getrusage.2	8.1	9/11/90
.TH getrusage 2
.SH Name
getrusage \- get information about resource utilization
.SH Syntax
.nf
.ft B
#include <sys/time.h>
#include <sys/resource.h>
.PP
.ft B
.ta \w'#define 'u +\w'RUSAGE_CHILDREN  'u +\w'-1        'u
#define	RUSAGE_SELF	0	/* calling process */
#define	RUSAGE_CHILDREN	-1	/* terminated child processes */
.DT
.PP
.ft B
getrusage(who, rusage)
int who;
struct rusage *rusage;
.fi
.SH Description
.NXB "getrusage system call"
.NXR "process" "getting information about resource utilization"
The
.PN getrusage
system call
returns information describing the resources utilized by the current
process or all its terminated child processes.
The
.I who
parameter is one of RUSAGE_SELF and RUSAGE_CHILDREN.
If
.I rusage
is nonzero, the buffer it points to will be filled in with
the following structure:
.EX 0
struct  rusage {
        struct timeval ru_utime;        /* user time used */
        struct timeval ru_stime;        /* system time used */
        int     ru_maxrss;
        int     ru_ixrss;       /* integral shared text size */
        int     ru_ismrss       /* integral shared memory size */
        int     ru_idrss;       /* integral unshared data size */
        int     ru_isrss;       /* integral unshared stack size */
        int     ru_minflt;      /* page reclaims */
        int     ru_majflt;      /* page faults */
        int     ru_nswap;       /* swaps */
        int     ru_inblock;     /* block input operations */
        int     ru_oublock;     /* block output operations */
        int     ru_msgsnd;      /* messages sent */
        int     ru_msgrcv;      /* messages received */
        int     ru_nsignals;    /* signals received */
        int     ru_nvcsw;       /* voluntary context switches */
        int     ru_nivcsw;      /* involuntary context switches */
};
.EE
.PP
The fields are interpreted as follows:
.NXB "getrusage system call" "fields"
.TP
.I ru_utime
The total amount of time spent executing in user mode.
.TP
.I ru_stime
The total amount of time spent in the system executing on behalf
of the processes.
.TP
.I ru_maxrss
The maximum resident set size utilized (in bytes).
.TP
.I ru_ixrss
An \*(lqintegral\*(rq value indicating the amount of text memory used
that was also shared among other processes.  This value is expressed
in units of kilobytes * seconds-of-execution and is calculated by
summing the number of shared memory pages in use each time the internal
system clock ticks and then averaging over 1-second intervals.
.TP
.I ru_ismrss
An integral value of the amount of shared memory residing in the data
segment of a process (expressed in units of kilobytes *
seconds-of execution).
.TP
.I ru_idrss
An integral value of the amount of unshared memory residing in the
data segment of a process (expressed in units of
kilobytes * seconds-of-execution).
.TP
.I ru_isrss
An integral value of the amount of unshared memory residing in the
stack segment of a process (expressed in units of
kilobytes * seconds-of-execution).
.TP
.I ru_minflt
The number of page faults serviced without any I/O activity; here,
I/O activity is avoided by \*(lqreclaiming\*(rq a page frame from
the list of pages awaiting reallocation.
.TP
.I ru_majflt
The number of page faults serviced that required I/O activity.
.TP
.I ru_nswap
The number of times a process was \*(lqswapped\*(rq out of main
memory.
.TP
.I ru_inblock
The number of times the file system had to perform input.
.TP
.I ru_oublock
The number of times the file system had to perform output.
.TP
.I ru_msgsnd
The number of ipc messages sent.
.TP
.I ru_msgrcv
The number of ipc messages received.
.TP
.I ru_nsignals
The number of signals delivered.
.TP
.I 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.
.TP
.I 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.
.NXE "getrusage system call" "fields"
.PP
The numbers 
.I ru_inblock 
and 
.I ru_oublock 
account only for real
I/O.  Data supplied by the cacheing mechanism is charged only
to the first process to read or write the data.
.SH Restrictions
.NXR "getrusage system call" "restricted"
There is no way to obtain information about a child process
that has not yet terminated.
.SH Diagnostics
.NXR "getrusage system call" "diagnostics"
The 
.PN getrusage
call fails under the following conditions:
.TP 15
[EINVAL]
The
.I who
parameter is not a valid value on RUSAGE_SELF or RUSAGE_CHILDREN.
.TP
[EFAULT]
The address specified by the
.I rusage
parameter is not in a valid part of the process address
space.
.SH See Also
gettimeofday(2), wait(2)
.NXE "getrusage system call"