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authorJens Axboe <axboe@kernel.dk>2022-10-03 16:56:40 -0600
committerJens Axboe <axboe@kernel.dk>2022-10-03 16:56:40 -0600
commit056c03ae90f6785463cd58554b7dd5bbe0ab3d2e (patch)
tree1b8977aa8a3c934ceeb464d021c5ae6b8ae8c71b
parent0fd4111a36db1cf5105b118f0a29fa3fc01327a2 (diff)
downloadliburing-master.tar.gz
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man/io_uring_register_files.3: clarify why registered files existHEADmaster
Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--man/io_uring_register_files.37
1 files changed, 7 insertions, 0 deletions
diff --git a/man/io_uring_register_files.3 b/man/io_uring_register_files.3
index 0a9ccc3..3feac4e 100644
--- a/man/io_uring_register_files.3
+++ b/man/io_uring_register_files.3
@@ -38,6 +38,13 @@ and later.
Registering a file table is a prerequisite for using any request that uses
direct descriptors.
+Registered files have less overhead per operation than normal files. This
+is due to the kernel grabbing a reference count on a file when an operation
+begins, and dropping it when it's done. When the process file table is
+shared, for example if the process has ever created any threads, then this
+cost goes up even more. Using registered files reduces the overhead of
+file reference management across requests that operate on a file.
+
.SH RETURN VALUE
On success
.BR io_uring_register_files (3)