EPOLL_CREATE
Section: Linux Programmer's Manual (2)
Updated: 2009-01-17
NAME
epoll_create, epoll_create1 - open an epoll file descriptor
SYNOPSIS
#include <sys/epoll.h>
int epoll_create(int size);
int epoll_create1(int flags);
DESCRIPTION
epoll_create()
creates an epoll "instance",
requesting the kernel to allocate an event backing store dimensioned for
size
descriptors.
The
size
is not the maximum size of the backing store but
just a hint to the kernel about how to dimension internal structures.
(Nowadays,
size
is ignored; see NOTES below.)
epoll_create()
returns a file descriptor referring to the new epoll instance.
This file descriptor is used for all the subsequent calls to the
epoll
interface.
When no longer required, the file descriptor returned by
epoll_create()
should be closed by using
close(2).
When all file descriptors referring to an epoll instance have been closed,
the kernel destroys the instance
and releases the associated resources for reuse.
If
flags
is 0, then, other than the fact that the obsolete
size
argument is dropped,
epoll_create1()
is the same as
epoll_create().
The following value can be included in
flags
to obtain different behavior:
- EPOLL_CLOEXEC
-
Set the close-on-exec
(FD_CLOEXEC)
flag on the new file descriptor.
See the description of the
O_CLOEXEC
flag in
open(2)
for reasons why this may be useful.
RETURN VALUE
On success,
these system calls
return a nonnegative file descriptor.
On error, -1 is returned, and
errno
is set to indicate the error.
ERRORS
- EINVAL
-
size
is not positive.
- EINVAL
-
(epoll_create1())
Invalid value specified in
flags.
- EMFILE
-
The per-user limit on the number of epoll instances imposed by
/proc/sys/fs/epoll/max_user_instances
was encountered.
See
epoll(7)
for further details.
- ENFILE
-
The system limit on the total number of open files has been reached.
- ENOMEM
-
There was insufficient memory to create the kernel object.
CONFORMING TO
epoll_create()
is Linux-specific, and was introduced in kernel 2.5.44.
NOTES
Since Linux 2.6.8, the
size
argument is unused.
(The kernel dynamically sizes the required data structures
without needing this initial hint.)
SEE ALSO
close(2),
epoll_ctl(2),
epoll_wait(2),
epoll(7)
COLOPHON
This page is part of release 3.27 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- CONFORMING TO
-
- NOTES
-
- SEE ALSO
-
- COLOPHON
-
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Time: 07:34:56 GMT, March 26, 2013