|EPOLL_CREATE(2)||Linux Programmer's Manual||EPOLL_CREATE(2)|
NAMEepoll_create, epoll_create1 - open an epoll file descriptor
int epoll_create(int size );
int epoll_create1(int flags );
DESCRIPTIONepoll_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_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:
- 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 VALUEOn success, these system calls return a nonnegative file descriptor. On error, -1 is returned, and errno is set to indicate the error.
- size is not positive.
- ( epoll_create1()) Invalid value specified in flags.
- 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.
- The system limit on the total number of open files has been reached.
- There was insufficient memory to create the kernel object.
VERSIONSepoll_create() was added to the kernel in version 2.6. Library support is provided in glibc starting with version 2.3.2.
CONFORMING TOepoll_create() is Linux-specific.
NOTESIn 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 internal 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 ALSOclose(2), epoll_ctl(2), epoll_wait(2), epoll(7)
COLOPHONThis 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/.