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diff --git a/man3p/pthread_getconcurrency.3p b/man3p/pthread_getconcurrency.3p new file mode 100644 index 000000000..7928ea538 --- /dev/null +++ b/man3p/pthread_getconcurrency.3p @@ -0,0 +1,110 @@ +.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved +.TH "PTHREAD_GETCONCURRENCY" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual" +.\" pthread_getconcurrency +.SH NAME +pthread_getconcurrency, pthread_setconcurrency \- get and set the level +of concurrency +.SH SYNOPSIS +.LP +\fB#include <pthread.h> +.br +.sp +int pthread_getconcurrency(void); +.br +int pthread_setconcurrency(int\fP \fInew_level\fP\fB); \fP +\fB +.br +\fP +.SH DESCRIPTION +.LP +Unbound threads in a process may or may not be required to be simultaneously +active. By default, the threads implementation +ensures that a sufficient number of threads are active so that the +process can continue to make progress. While this conserves +system resources, it may not produce the most effective level of concurrency. +.LP +The \fIpthread_setconcurrency\fP() function allows an application +to inform the threads implementation of its desired +concurrency level, \fInew_level\fP. The actual level of concurrency +provided by the implementation as a result of this function +call is unspecified. +.LP +If \fInew_level\fP is zero, it causes the implementation to maintain +the concurrency level at its discretion as if +\fIpthread_setconcurrency\fP() had never been called. +.LP +The \fIpthread_getconcurrency\fP() function shall return the value +set by a previous call to the +\fIpthread_setconcurrency\fP() function. If the \fIpthread_setconcurrency\fP() +function was not previously called, this function +shall return zero to indicate that the implementation is maintaining +the concurrency level. +.LP +A call to \fIpthread_setconcurrency\fP() shall inform the implementation +of its desired concurrency level. The implementation +shall use this as a hint, not a requirement. +.LP +If an implementation does not support multiplexing of user threads +on top of several kernel-scheduled entities, the +\fIpthread_setconcurrency\fP() and \fIpthread_getconcurrency\fP() +functions are provided for source code compatibility but they +shall have no effect when called. To maintain the function semantics, +the \fInew_level\fP parameter is saved when +\fIpthread_setconcurrency\fP() is called so that a subsequent call +to \fIpthread_getconcurrency\fP() shall return the same +value. +.SH RETURN VALUE +.LP +If successful, the \fIpthread_setconcurrency\fP() function shall return +zero; otherwise, an error number shall be returned to +indicate the error. +.LP +The \fIpthread_getconcurrency\fP() function shall always return the +concurrency level set by a previous call to +\fIpthread_setconcurrency\fP(). If the \fIpthread_setconcurrency\fP() +function has never been called, +\fIpthread_getconcurrency\fP() shall return zero. +.SH ERRORS +.LP +The \fIpthread_setconcurrency\fP() function shall fail if: +.TP 7 +.B EINVAL +The value specified by \fInew_level\fP is negative. +.TP 7 +.B EAGAIN +The value specific by \fInew_level\fP would cause a system resource +to be exceeded. +.sp +.LP +These functions shall not return an error code of [EINTR]. +.LP +\fIThe following sections are informative.\fP +.SH EXAMPLES +.LP +None. +.SH APPLICATION USAGE +.LP +Use of these functions changes the state of the underlying concurrency +upon which the application depends. Library developers +are advised to not use the \fIpthread_getconcurrency\fP() and \fIpthread_setconcurrency\fP() +functions since their use may +conflict with an applications use of these functions. +.SH RATIONALE +.LP +None. +.SH FUTURE DIRECTIONS +.LP +None. +.SH SEE ALSO +.LP +The Base Definitions volume of IEEE\ Std\ 1003.1-2001, \fI<pthread.h>\fP +.SH COPYRIGHT +Portions of this text are reprinted and reproduced in electronic form +from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology +-- Portable Operating System Interface (POSIX), The Open Group Base +Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of +Electrical and Electronics Engineers, Inc and The Open Group. In the +event of any discrepancy between this version and the original IEEE and +The Open Group Standard, the original IEEE and The Open Group Standard +is the referee document. The original Standard can be obtained online at +http://www.opengroup.org/unix/online.html . |