EPOLL_CREATE(2) 					     Linux Programmer's Manual						   EPOLL_CREATE(2)

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(7)  instance.  Since Linux 2.6.8, the size argument is ignored, but must be greater than zero; 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.

   epoll_create1()
       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  rea-
	      sons 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.

VERSIONS

       epoll_create() was added to the kernel in version 2.6.  Library support is provided in glibc starting with version 2.3.2.

       epoll_create1() was added to the kernel in version 2.6.27.  Library support is provided in glibc starting with version 2.9.

CONFORMING TO

       epoll_create() is Linux-specific.

NOTES

       In the initial epoll_create() implementation, the size argument informed the kernel of the number  of  file  descriptors  that  the  caller
       expected  to add to the epoll instance.	The kernel used this information as a hint for the amount of space to initially allocate in inter-
       nal data structures describing events.  (If necessary, the kernel would allocate more space if the caller's usage exceeded the  hint  given
       in  size.)  Nowadays, this hint is no longer required (the kernel dynamically sizes the required data structures without needing the hint),
       but size must still be greater than zero, in order to ensure backward compatibility when new epoll applications are run on older kernels.

SEE ALSO

       close(2), epoll_ctl(2), epoll_wait(2), epoll(7)

COLOPHON

       This page is part of release 3.53 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/.

Linux								    2012-04-15							   EPOLL_CREATE(2)