Section: Linux Programmer's Manual (2)
epoll_create, epoll_create1 - open an epoll file descriptor
int epoll_create(int size);
int epoll_create1(int flags);
creates a new
Since Linux 2.6.8, the
argument is ignored, but must be greater than zero; see NOTES.
returns a file descriptor referring to the new epoll instance.
This file descriptor is used for all the subsequent calls to the
When no longer required, the file descriptor returned by
should be closed by using
When all file descriptors referring to an epoll instance have been closed,
the kernel destroys the instance
and releases the associated resources for reuse.
is 0, then, other than the fact that the obsolete
argument is dropped,
is the same as
The following value can be included in
to obtain different behavior:
Set the close-on-exec
flag on the new file descriptor.
See the description of the
for reasons why this may be useful.
these system calls
return a file descriptor (a nonnegative integer).
On error, -1 is returned, and
is set to indicate the error.
is not positive.
Invalid value specified in
The per-user limit on the number of epoll instances imposed by
for further details.
The per-process limit on the number of open file descriptors has been reached.
The system-wide limit on the total number of open files has been reached.
There was insufficient memory to create the kernel object.
was added to the kernel in version 2.6.
Library support is provided in glibc starting with version 2.3.2.
was added to the kernel in version 2.6.27.
Library support is provided in glibc starting with version 2.9.
In the initial
argument informed the kernel of the number of file descriptors
that the caller expected to add to the
The kernel used this information as a hint for the amount of
space to initially allocate in internal data structures describing events.
(If necessary, the kernel would allocate more space
if the caller's usage exceeded the hint given in
this hint is no longer required
(the kernel dynamically sizes the required data structures
without needing the hint), but
must still be greater than zero,
in order to ensure backward compatibility when new
applications are run on older kernels.
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