[PATCH 0/5] skip request refcounting

[Pavel Begunkov <asml.silence@gmail.com>]

With some tricks, we can avoid refcounting in most of the cases and
so save on atomics. The series implements this optimisation. 1-4 are
simple enough preparations, the biggest part is 5/5. Would be great
to have extra pair of eyes on it.

Jens tried out a prototype before, apparently it gave ~3% win for
the default read test. Not much has changed since then, so I'd
expect same result, and also hope that it should be of even greater
benefit to multithreaded workloads.

Pavel Begunkov (5):
  io_uring: move req_ref_get() and friends
  io_uring: delay freeing ->async_data
  io_uring: protect rsrc dealloc by uring_lock
  io_uring: remove req_ref_sub_and_test()
  io_uring: request refcounting skipping

 fs/io_uring.c | 176 +++++++++++++++++++++++++++++---------------------
 1 file changed, 101 insertions(+), 75 deletions(-)

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2.32.0