(libc.info.gz) Resource Usage

Info Catalog

(libc.info.gz) Resource Usage And Limitation

(libc.info.gz) Limits on Resources

 
 22.1 Resource Usage
 ===================
 
 The function 'getrusage' and the data type 'struct rusage' are used to
 examine the resource usage of a process.  They are declared in
 'sys/resource.h'.
 
  -- Function: int getrusage (int PROCESSES, struct rusage *RUSAGE)
      Preliminary: | MT-Safe | AS-Safe | AC-Safe |  POSIX Safety
      Concepts.
 
      This function reports resource usage totals for processes specified
      by PROCESSES, storing the information in '*RUSAGE'.
 
      In most systems, PROCESSES has only two valid values:
 
      'RUSAGE_SELF'
           Just the current process.
 
      'RUSAGE_CHILDREN'
           All child processes (direct and indirect) that have already
           terminated.
 
      The return value of 'getrusage' is zero for success, and '-1' for
      failure.
 
      'EINVAL'
           The argument PROCESSES is not valid.
 
    One way of getting resource usage for a particular child process is
 with the function 'wait4', which returns totals for a child when it
 terminates.   BSD Wait Functions.
 
  -- Data Type: struct rusage
      This data type stores various resource usage statistics.  It has
      the following members, and possibly others:
 
      'struct timeval ru_utime'
           Time spent executing user instructions.
 
      'struct timeval ru_stime'
           Time spent in operating system code on behalf of PROCESSES.
 
      'long int ru_maxrss'
           The maximum resident set size used, in kilobytes.  That is,
           the maximum number of kilobytes of physical memory that
           PROCESSES used simultaneously.
 
      'long int ru_ixrss'
           An integral value expressed in kilobytes times ticks of
           execution, which indicates the amount of memory used by text
           that was shared with other processes.
 
      'long int ru_idrss'
           An integral value expressed the same way, which is the amount
           of unshared memory used for data.
 
      'long int ru_isrss'
           An integral value expressed the same way, which is the amount
           of unshared memory used for stack space.
 
      'long int ru_minflt'
           The number of page faults which were serviced without
           requiring any I/O.
 
      'long int ru_majflt'
           The number of page faults which were serviced by doing I/O.
 
      'long int ru_nswap'
           The number of times PROCESSES was swapped entirely out of main
           memory.
 
      'long int ru_inblock'
           The number of times the file system had to read from the disk
           on behalf of PROCESSES.
 
      'long int ru_oublock'
           The number of times the file system had to write to the disk
           on behalf of PROCESSES.
 
      'long int ru_msgsnd'
           Number of IPC messages sent.
 
      'long int ru_msgrcv'
           Number of IPC messages received.
 
      'long int ru_nsignals'
           Number of signals received.
 
      'long int ru_nvcsw'
           The number of times PROCESSES voluntarily invoked a context
           switch (usually to wait for some service).
 
      'long int ru_nivcsw'
           The number of times an involuntary context switch took place
           (because a time slice expired, or another process of higher
           priority was scheduled).
 
    'vtimes' is a historical function that does some of what 'getrusage'
 does.  'getrusage' is a better choice.
 
    'vtimes' and its 'vtimes' data structure are declared in
 'sys/vtimes.h'.
 
  -- Function: int vtimes (struct vtimes *CURRENT, struct vtimes *CHILD)
      Preliminary: | MT-Safe | AS-Safe | AC-Safe |  POSIX Safety
      Concepts.
 
      'vtimes' reports resource usage totals for a process.
 
      If CURRENT is non-null, 'vtimes' stores resource usage totals for
      the invoking process alone in the structure to which it points.  If
      CHILD is non-null, 'vtimes' stores resource usage totals for all
      past children (which have terminated) of the invoking process in
      the structure to which it points.
 
       -- Data Type: struct vtimes
           This data type contains information about the resource usage
           of a process.  Each member corresponds to a member of the
           'struct rusage' data type described above.
 
           'vm_utime'
                User CPU time.  Analogous to 'ru_utime' in 'struct
                rusage'
           'vm_stime'
                System CPU time.  Analogous to 'ru_stime' in 'struct
                rusage'
           'vm_idsrss'
                Data and stack memory.  The sum of the values that would
                be reported as 'ru_idrss' and 'ru_isrss' in 'struct
                rusage'
           'vm_ixrss'
                Shared memory.  Analogous to 'ru_ixrss' in 'struct
                rusage'
           'vm_maxrss'
                Maximent resident set size.  Analogous to 'ru_maxrss' in
                'struct rusage'
           'vm_majflt'
                Major page faults.  Analogous to 'ru_majflt' in 'struct
                rusage'
           'vm_minflt'
                Minor page faults.  Analogous to 'ru_minflt' in 'struct
                rusage'
           'vm_nswap'
                Swap count.  Analogous to 'ru_nswap' in 'struct rusage'
           'vm_inblk'
                Disk reads.  Analogous to 'ru_inblk' in 'struct rusage'
           'vm_oublk'
                Disk writes.  Analogous to 'ru_oublk' in 'struct rusage'
 
      The return value is zero if the function succeeds; '-1' otherwise.
 
    An additional historical function for examining resource usage,
 'vtimes', is supported but not documented here.  It is declared in
 'sys/vtimes.h'.
 

Info Catalog

(libc.info.gz) Resource Usage And Limitation

(libc.info.gz) Limits on Resources