/** @file ../include/sys/resource.h

@internalComponent

*/

/** @fn  getpriority(int which, int who)

@param which

@param who

Note: This description also covers the following functions -

 setpriority() 

@return   Since getpriority can legitimately return the value -1, it is necessary

to clear the external variable errno prior to the

call, then check it afterward to determine

if a -1 is an error or a legitimate value. The setpriority returns 0 on success and -1 on error with the errno set.

  The scheduling

priority of the process, process group, or user, as indicated by which and who is obtained with the getpriority system call and set with the setpriority system call.

The which argument

is one of PRIO_PROCESS, PRIO_PGRP, or PRIO_USER, and who is interpreted relative to which (a process identifier for PRIO_PROCESS, process group

identifier for PRIO_PGRP, and a user ID for PRIO_USER ). A zero value of who denotes the current process, process group, or user.

The prio argument

is a value in the range -20 to 20.

The default priority is 0;

lower priorities cause more favorable scheduling.

 If the prio is greater than the greatest priority supported, it is set to the greatest priority supported.

If the prio is lesser than the least priority supported, it is set to the least priority supported.

Examples:

@code

#include<sys/resource.h>        

#include<unistd.h>

#include<stdio.h>

int test_getpriority()

{

   int retVal;

   errno = 0;

   retVal = getpriority(PRIO_PROCESS, 0);

   if((retVal == -1) && (errno == ENOSYS))

   {

      printf("Failed");

      return -1;

   }

   else

   {

      printf("getpriority passed");

      printf("

priority = %d ", retVal);

   }    

   return 0;

}

@endcode

 Output

@code

getpriority passed

priority = 0

@endcode

@code

#include<sys/resource.h>        

#include<unistd.h>

#include<stdio.h>

int test_setpriority()

{

   int retVal;

   errno = 0;

   retVal = setpriority(PRIO_PROCESS, 0, 0);

   if((retVal == -1) && (errno == ENOSYS))

   {

      printf("Failed");

      return -1;

   }

   else

   {

      printf("Setpriority passed");

      printf(" getpriority now: %d", getpriority(PRIO_PROCESS,0))

    }   

   return 0;

}

@endcode

 Output

@code

Setpriority passed

getpriority now: 0

@endcode

Limitations:

1. The values PRIO_PGRP and PRIO_USER for the which and any value other than 0 for who are not supported, when given return ENOSYS. 

2. To effectively increase or decrease the priority of the process, one should consider the following:  

Highest                                                                 -16 to -20         Above Normal                                                     -6 to -15         Normal                                                                          +4 to -5         Below Normal                                                    +14 to +5         Lowest                                                                    +20 to +15 3. 

The setting of the priority to values -16 to -20 is not supported, the use of which sets errno to EINVAL.

@see nice()

@publishedAll

@externallyDefinedApi

*/

/** @fn  setpriority(int which, int who, int value)

@param which

@param who

@param value

Refer to  getpriority() for the documentation

@see nice()

@publishedAll

@externallyDefinedApi

*/

/** @struct rlimit

Contains the following members,

@publishedAll

@externallyDefinedApi

*/

/** @var rlimit::rlim_cur

current (soft) limit

*/

/** @var rlimit::rlim_max

maximum value for rlim_cur

*/

/** @struct rusage 

Contains the following members,

@publishedAll

@externallyDefinedApi

*/

/** @var rusage::ru_utime

user time used

*/

/** @var rusage::ru_stime

system time used

*/

/** @var rusage::ru_maxrss

max resident set size

*/

/** @var rusage::ru_ixrss

integral shared memory size

*/

/** @var rusage::ru_idrss

integral unshared data

*/

/** @var rusage::ru_isrss

integral unshared stack

*/

/** @var rusage::ru_minflt

page reclaims

*/

/** @var rusage::ru_majflt

page faults

*/

/** @var rusage::ru_nswap

(c + j) swaps

*/

/** @var rusage::ru_inblock

block input operations

*/

/** @var rusage::ru_oublock

block output operations

*/

/** @var rusage::ru_msgsnd

messages sent

*/

/** @var rusage::ru_msgrcv

 messages received 

*/

/** @var rusage::ru_nsignals

signals received

*/

/** @var rusage::ru_nvcsw

voluntary context switches

*/

/** @var rusage::ru_nivcsw

involuntary

*/

/** @typedef typedef	__rlim_t	rlim_t

Unsigned integer type used for limit values.

@publishedAll

@externallyDefinedApi

*/

/** @def RLIM_INFINITY

unsigned long int

@publishedAll

@externallyDefinedApi

*/

/** @def RLIMIT_CORE

core file size 

@publishedAll

@externallyDefinedApi

*/

/** @def RLIMIT_CPU

cpu time in milliseconds

@publishedAll

@externallyDefinedApi

*/

/** @def RLIMIT_DATA

data size

@publishedAll

@externallyDefinedApi

*/

/** @def RLIMIT_FSIZE

maximum file size

@publishedAll

@externallyDefinedApi

*/

/** @def RLIMIT_NOFILE

number of open files

@publishedAll

@externallyDefinedApi

*/

/** @def RLIMIT_STACK

stack size

@publishedAll

@externallyDefinedApi

*/

/** @def RLIMIT_AS

standard name for RLIMIT_VMEM

@publishedAll

@externallyDefinedApi

*/

/** @def RUSAGE_SELF

Resource utilization information.

@publishedAll

@externallyDefinedApi

*/

/** @def RUSAGE_CHILDREN

Resource utilization information.

@publishedAll

@externallyDefinedApi

*/

/** @def PRIO_PROCESS

Process priority specifications to get or set priority.

@publishedAll

@externallyDefinedApi

*/

/** @def PRIO_PGRP

Process priority specifications to get or set priority.

@publishedAll

@externallyDefinedApi

*/

/** @def PRIO_USER

Process priority specifications to get or set priority.

@publishedAll

@externallyDefinedApi

*/