5.20 cleanups and poll optimisations

1-4 kills REQ_F_COMPLETE_INLINE as we're out of bits.

Patch 5 from Hao should remove some overhead from poll requests

Patch 6 from Hao adds per-bucket spinlocks, and 16-19 do a little bit of cleanup. The downside of per-bucket spinlocks is that it adds additional spinlock/unlock pair in the poll request completion side, which shouldn't matter much with 20/25.

Patch 11 uses inline completion infra for poll requests, this nicely improves perf when there is a good tw batching.

Patch 12 implements the userspace visible side of IORING_SETUP_SINGLE_ISSUER, it'll be used for poll requests and later for spinlock optimisations.

13-16 introduces ->uring_lock protected cancellation hashing. It requires us to grab ->uring_lock in the completion side, but saves two spin lock/unlock pairs. We apply it automatically in cases the mutex is already likely to be held (see 25/25 description), so there is no additional mutex overhead and potential latency problemes.

Numbers:

The used poll benchmark each iteration queues a batch of 32 POLLIN poll requests and triggers all of them with read (+write).

baseline (patches 1-10):

    11720 K req/s
base + 11 (+ inline completion infra)
    12419 K req/s, ~+6%
base + 11-16 (+ uring_lock hashing):
    12804 K req/s, +9.2% from the baseline, or +3.2% relative to patch 19.

Note that patch 11 only helps performance of poll-add requests, whenever 16/16 also improves apoll.

v2:
don't move ->cancel_seq out of iowq work struct
fix up single-issuer

v3:
clarify locking expectation around ->uring_lock hashing don't complete by hand in io_read/write (see 1/16)

Hao Xu (2):
io_uring: poll: remove unnecessary req->ref set
io_uring: switch cancel_hash to use per entry spinlock

Pavel Begunkov (14):
io_uring: rw: delegate sync completions to core io_uring
io_uring: kill REQ_F_COMPLETE_INLINE
io_uring: refactor io_req_task_complete()
io_uring: don't inline io_put_kbuf
io_uring: pass poll_find lock back
io_uring: clean up io_try_cancel
io_uring: limit the number of cancellation buckets
io_uring: clean up io_ring_ctx_alloc
io_uring: use state completion infra for poll reqs
io_uring: add IORING_SETUP_SINGLE_ISSUER
io_uring: pass hash table into poll_find
io_uring: introduce a struct for hash table
io_uring: propagate locking state to poll cancel
io_uring: mutex locked poll hashing

 include/uapi/linux/io_uring.h |   5 +-
 io_uring/cancel.c             |  23 +++-
 io_uring/cancel.h             |   4 +-
 io_uring/fdinfo.c             |  11 +-
 io_uring/io_uring.c           |  84 ++++++++-----
 io_uring/io_uring.h           |   5 -
 io_uring/io_uring_types.h     |  21 +++-
 io_uring/kbuf.c               |  33 +++++
 io_uring/kbuf.h               |  38 +-----
 io_uring/poll.c               | 225 +++++++++++++++++++++++++---------
 io_uring/poll.h               |   3 +-
 io_uring/rw.c                 |  41 +++----
 io_uring/tctx.c               |  27 +++-
 io_uring/tctx.h               |   4 +-
 io_uring/timeout.c            |   3 +-
 15 files changed, 353 insertions(+), 174 deletions(-)

2.36.1