1EPOLL_CREATE(2) Linux Programmer's Manual EPOLL_CREATE(2)
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6 epoll_create, epoll_create1 - open an epoll file descriptor
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9 #include <sys/epoll.h>
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11 int epoll_create(int size);
12 int epoll_create1(int flags);
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15 epoll_create() creates an epoll "instance", requesting the kernel to
16 allocate an event backing store dimensioned for size descriptors. The
17 size is not the maximum size of the backing store but just a hint to
18 the kernel about how to dimension internal structures. (Nowadays, size
19 is ignored; see NOTES below.)
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21 epoll_create() returns a file descriptor referring to the new epoll
22 instance. This file descriptor is used for all the subsequent calls to
23 the epoll interface. When no longer required, the file descriptor
24 returned by epoll_create() should be closed by using close(2). When
25 all file descriptors referring to an epoll instance have been closed,
26 the kernel destroys the instance and releases the associated resources
27 for reuse.
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29 If flags is 0, then, other than the fact that the obsolete size argu‐
30 ment is dropped, epoll_create1() is the same as epoll_create(). The
31 following value can be included in flags to obtain different behavior:
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33 EPOLL_CLOEXEC
34 Set the close-on-exec (FD_CLOEXEC) flag on the new file descrip‐
35 tor. See the description of the O_CLOEXEC flag in open(2) for
36 reasons why this may be useful.
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39 On success, these system calls return a nonnegative file descriptor.
40 On error, -1 is returned, and errno is set to indicate the error.
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43 EINVAL size is not positive.
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45 EINVAL (epoll_create1()) Invalid value specified in flags.
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47 EMFILE The per-user limit on the number of epoll instances imposed by
48 /proc/sys/fs/epoll/max_user_instances was encountered. See
49 epoll(7) for further details.
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51 ENFILE The system limit on the total number of open files has been
52 reached.
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54 ENOMEM There was insufficient memory to create the kernel object.
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57 epoll_create() is Linux-specific, and was introduced in kernel 2.5.44.
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60 Since Linux 2.6.8, the size argument is unused. (The kernel dynami‐
61 cally sizes the required data structures without needing this initial
62 hint.)
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65 close(2), epoll_ctl(2), epoll_wait(2), epoll(7)
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68 This page is part of release 3.25 of the Linux man-pages project. A
69 description of the project, and information about reporting bugs, can
70 be found at http://www.kernel.org/doc/man-pages/.
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74Linux 2009-01-17 EPOLL_CREATE(2)