getrusage(2)

1GETRUSAGE(2)               Linux Programmer's Manual              GETRUSAGE(2)
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NAME

6       getrusage - get resource usage
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SYNOPSIS

9       #include <sys/time.h>
10       #include <sys/resource.h>
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12       int getrusage(int who, struct rusage *usage);
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DESCRIPTION

15       getrusage()  returns  current  resource  usages,  for  a  who of either
16       RUSAGE_SELF or RUSAGE_CHILDREN.  The former asks for resources used  by
17       the  current  process,  the  latter  for resources used by those of its
18       children that have terminated and have been waited for.
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20            struct rusage {
21                struct timeval ru_utime; /* user time used */
22                struct timeval ru_stime; /* system time used */
23                long   ru_maxrss;        /* maximum resident set size */
24                long   ru_ixrss;         /* integral shared memory size */
25                long   ru_idrss;         /* integral unshared data size */
26                long   ru_isrss;         /* integral unshared stack size */
27                long   ru_minflt;        /* page reclaims */
28                long   ru_majflt;        /* page faults */
29                long   ru_nswap;         /* swaps */
30                long   ru_inblock;       /* block input operations */
31                long   ru_oublock;       /* block output operations */
32                long   ru_msgsnd;        /* messages sent */
33                long   ru_msgrcv;        /* messages received */
34                long   ru_nsignals;      /* signals received */
35                long   ru_nvcsw;         /* voluntary context switches */
36                long   ru_nivcsw;        /* involuntary context switches */
37            };
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RETURN VALUE

40       On success, zero is returned.  On error, -1 is returned, and  errno  is
41       set appropriately.
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ERRORS

44       EFAULT usage points outside the accessible address space.
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46       EINVAL who is invalid.
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CONFORMING TO

49       SVr4,  4.3BSD.   POSIX.1-2001 specifies getrusage(), but only specifies
50       the fields ru_utime and ru_stime.
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NOTES

53       Including <sys/time.h> is not required these days, but increases porta‐
54       bility.  (Indeed, struct timeval is defined in <sys/time.h>.)
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56       In Linux kernel versions before 2.6.9, if the disposition of SIGCHLD is
57       set to SIG_IGN then the resource usages of child processes are automat‐
58       ically  included  in  the  value  returned by RUSAGE_CHILDREN, although
59       POSIX.1-2001 explicitly prohibits this.  This non-conformance is recti‐
60       fied in Linux 2.6.9 and later.
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62       The  above struct was taken from 4.3BSD Reno.  Not all fields are mean‐
63       ingful under Linux.  In linux 2.4 only the fields  ru_utime,  ru_stime,
64       ru_minflt, and ru_majflt are maintained.  Since Linux 2.6, ru_nvcsw and
65       ru_nivcsw are also maintained.
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