1io_uring_register_files(3)      liburing Manual     io_uring_register_files(3)
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NAME

6       io_uring_register_files - register file descriptors
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SYNOPSIS

9       #include <liburing.h>
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11       int io_uring_register_files(struct io_uring *ring,
12                                   const int *files,
13                                   unsigned nr_files);
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15       int io_uring_register_files_sparse(struct io_uring *ring,
16                                   unsigned nr_files);
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DESCRIPTION

19       The  io_uring_register_files(3)  function  registers nr_files number of
20       file descriptors defined by the array files belonging to the  ring  for
21       subsequent operations.
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23       The  io_uring_register_files_sparse(3) function registers an empty file
24       table of nr_files number of file descriptors.  The  sparse  variant  is
25       available in kernels 5.19 and later.
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27       Registering  a  file table is a prerequisite for using any request that
28       uses direct descriptors.
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30       Registered files have less overhead per operation  than  normal  files.
31       This  is due to the kernel grabbing a reference count on a file when an
32       operation begins, and dropping it when it's done. When the process file
33       table  is  shared,  for  example  if  the  process has ever created any
34       threads, then this cost goes up even more. Using registered  files  re‐
35       duces  the  overhead  of file reference management across requests that
36       operate on a file.
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RETURN VALUE

40       On    success    io_uring_register_files(3)     and     io_uring_regis‐
41       ter_files_sparse(3) return 0. On failure they return -errno.
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SEE ALSO

44       io_uring_get_sqe(3), io_uring_unregister_files(3)
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48liburing-2.1                   November 15, 2021    io_uring_register_files(3)