/** @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
*/