mirror of https://github.com/mkerrisk/man-pages
103 lines
3.6 KiB
Plaintext
103 lines
3.6 KiB
Plaintext
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "PTHREAD_SETSCHEDPRIO" 3P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" pthread_setschedprio
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.SH NAME
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pthread_setschedprio \- dynamic thread scheduling parameters access
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(\fBREALTIME THREADS\fP)
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.SH SYNOPSIS
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.LP
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\fB#include <pthread.h>
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.br
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.sp
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int pthread_setschedprio(pthread_t\fP \fIthread\fP\fB, int\fP \fIprio\fP\fB);
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\fP
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\fB
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.br
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\fP
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.SH DESCRIPTION
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.LP
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The \fIpthread_setschedprio\fP() function shall set the scheduling
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priority for the thread whose thread ID is given by
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\fIthread\fP to the value given by \fIprio\fP. See \fIScheduling Policies\fP
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for a description on how this function call affects the ordering of
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the thread in the thread list for its new priority.
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.LP
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If the \fIpthread_setschedprio\fP() function fails, the scheduling
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priority of the target thread shall not be changed.
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.SH RETURN VALUE
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.LP
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If successful, the \fIpthread_setschedprio\fP() function shall return
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zero; otherwise, an error number shall be returned to
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indicate the error.
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.SH ERRORS
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.LP
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The \fIpthread_setschedprio\fP() function may fail if:
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.TP 7
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.B EINVAL
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The value of \fIprio\fP is invalid for the scheduling policy of the
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specified thread.
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.TP 7
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.B ENOTSUP
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An attempt was made to set the priority to an unsupported value.
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.TP 7
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.B EPERM
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The caller does not have the appropriate permission to set the scheduling
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policy of the specified thread.
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.TP 7
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.B EPERM
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The implementation does not allow the application to modify the priority
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to the value specified.
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.TP 7
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.B ESRCH
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The value specified by \fIthread\fP does not refer to an existing
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thread.
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.sp
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.LP
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The \fIpthread_setschedprio\fP() function shall not return an error
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code of [EINTR].
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.LP
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\fIThe following sections are informative.\fP
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.SH EXAMPLES
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.LP
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None.
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.SH APPLICATION USAGE
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.LP
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None.
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.SH RATIONALE
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.LP
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The \fIpthread_setschedprio\fP() function provides a way for an application
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to temporarily raise its priority and then lower it
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again, without having the undesired side effect of yielding to other
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threads of the same priority. This is necessary if the
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application is to implement its own strategies for bounding priority
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inversion, such as priority inheritance or priority ceilings.
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This capability is especially important if the implementation does
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not support the Thread Priority Protection or Thread Priority
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Inheritance options, but even if those options are supported it is
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needed if the application is to bound priority inheritance for
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other resources, such as semaphores.
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.LP
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The standard developers considered that while it might be preferable
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conceptually to solve this problem by modifying the
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specification of \fIpthread_setschedparam\fP(), it was too late to
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make such
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a change, as there may be implementations that would need to be changed.
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Therefore, this new function was introduced.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fIScheduling Policies\fP , \fIpthread_getschedparam\fP() , the Base
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Definitions volume of IEEE\ Std\ 1003.1-2001, \fI<pthread.h>\fP
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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