Section: Linux Programmer's Manual (3)
Return to Main Contents
pthread_setconcurrency, pthread_getconcurrency - set/get
the concurrency level
int pthread_setconcurrency(int new_level);
Compile and link with -pthread.
function informs the implementation of the application's
desired concurrency level, specified in
The implementation takes this only as a hint:
POSIX.1 does not specify the level of concurrency that
should be provided as a result of calling
as 0 instructs the implementation to manage the concurrency level
as it deems appropriate.
returns the current value of the concurrency level for this process.
on error, it returns a nonzero error number.
always succeeds, returning the concurrency level set by a previous call to
or 0, if
has not previously been called.
can fail with the following error:
POSIX.1 also documents an
error ("the value specified by
would cause a system resource to be exceeded").
These functions are available in glibc since version 2.1.
For an explanation of the terms used in this section, see
The default concurrency level is 0.
Concurrency levels are meaningful only for M:N threading implementations,
where at any moment a subset of a process's set of user-level threads
may be bound to a smaller number of kernel-scheduling entities.
Setting the concurrency level allows the application to
give the system a hint as to the number of kernel-scheduling entities
that should be provided for efficient execution of the application.
Both LinuxThreads and NPTL are 1:1 threading implementations,
so setting the concurrency level has no meaning.
In other words,
on Linux these functions merely exist for compatibility with other systems,
and they have no effect on the execution of a program.
This page is part of release 4.15 of the Linux
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
- RETURN VALUE
- CONFORMING TO
- SEE ALSO
This document was created by
using the manual pages.
Time: 23:09:55 GMT, September 24, 2018