pthread_attr_getschedpolicy (original) (raw)

The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2004 Edition
Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.

A newer edition of this document exists here

NAME

pthread_attr_getschedpolicy, pthread_attr_setschedpolicy - get and set the schedpolicy attribute (REALTIME THREADS)

SYNOPSIS

`[THR TPS] [Option Start] #include <pthread.h>

int pthread_attr_getschedpolicy(const pthread_attr_t *restrict

attr,
int *restrict policy);
int pthread_attr_setschedpolicy(pthread_attr_t *attr, int policy); [Option End]`

DESCRIPTION

The pthread_attr_getschedpolicy() and pthread_attr_setschedpolicy() functions, respectively, shall get and set the_schedpolicy_ attribute in the attr argument.

The supported values of policy shall include SCHED_FIFO, SCHED_RR, and SCHED_OTHER, which are defined in the <sched.h> header. When threads executing with the scheduling policy SCHED_FIFO, SCHED_RR, [TSP] [Option Start] or SCHED_SPORADIC [Option End] are waiting on a mutex, they shall acquire the mutex in priority order when the mutex is unlocked.

RETURN VALUE

If successful, the pthread_attr_getschedpolicy() and pthread_attr_setschedpolicy() functions shall return zero; otherwise, an error number shall be returned to indicate the error.

ERRORS

The pthread_attr_getschedpolicy() function may fail if:

[EINVAL]

The value specified by attr does not refer to an initialized thread attribute object.

The pthread_attr_setschedpolicy() function may fail if:

[EINVAL]

The value of policy is not valid, or the value specified by attr does not refer to an initialized thread attribute object.

[ENOTSUP]

An attempt was made to set the attribute to an unsupported value.

These functions shall not return an error code of [EINTR].

The following sections are informative.

EXAMPLES

None.

APPLICATION USAGE

After these attributes have been set, a thread can be created with the specified attributes using pthread_create(). Using these routines does not affect the current running thread.

See Thread Scheduling for further details on thread scheduling attributes and their default settings.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

pthread_attr_destroy(), pthread_attr_getscope(), pthread_attr_getinheritsched(), pthread_attr_getschedparam(), pthread_create(), the Base Definitions volume of IEEE Std 1003.1-2001, <pthread.h>, <sched.h>

CHANGE HISTORY

First released in Issue 5. Included for alignment with the POSIX Threads Extension.

Marked as part of the Realtime Threads Feature Group.

Issue 6

The pthread_attr_getschedpolicy() and pthread_attr_setschedpolicy() functions are marked as part of the Threads and Thread Execution Scheduling options.

The [ENOSYS] error condition has been removed as stubs need not be provided if an implementation does not support the Thread Execution Scheduling option.

The SCHED_SPORADIC scheduling policy is added for alignment with IEEE Std 1003.1d-1999.

The restrict keyword is added to the pthread_attr_getschedpolicy() prototype for alignment with the ISO/IEC 9899:1999 standard.

IEEE Std 1003.1-2001/Cor 2-2004, item XSH/TC2/D6/79 is applied, adding a reference to Thread Scheduling in the APPLICATION USAGE section.

IEEE Std 1003.1-2001/Cor 2-2004, item XSH/TC2/D6/80 is applied, updating the ERRORS section to include optional errors for the case when attr refers to an uninitialized thread attribute object.

End of informative text.

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