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 "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 indi-
       cate 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 encoun-
              tered.  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 need-
       ing this initial hint.)

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

COLOPHON
       This  page  is  part of release 3.25 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                                                      2009-01-17                                            EPOLL_CREATE(2)