[for-next,v2,00/25] 5.20 cleanups and poll optimisations

Message

Pavel Begunkov June 14, 2022, 2:36 p.m. UTC

1-13 are cleanups after splitting io_uring into files.

Patch 14 from Hao should remove some overhead from poll requests

Patch 15 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 20 uses inline completion infra for poll requests, this nicely
improves perf when there is a good tw batching.

Patch 21 implements the userspace visible side of
IORING_SETUP_SINGLE_ISSUER, it'll be used for poll requests and
later for spinlock optimisations.

22-25 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 1-18):
    11720 K req/s
base + 19 (+ inline completion infra)
    12419 K req/s, ~+6%
base + 19-25 (+ uring_lock hashing):
    12804 K req/s, +9.2% from the baseline, or +3.2% relative to patch 19.

Note that patch 19 only helps performance of poll-add requests, whenever
25/25 also improves apoll.

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

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

Pavel Begunkov (23):
  io_uring: make reg buf init consistent
  io_uring: move defer_list to slow data
  io_uring: better caching for ctx timeout fields
  io_uring: refactor ctx slow data placement
  io_uring: move small helpers to headers
  io_uring: explain io_wq_work::cancel_seq placement
  io_uring: inline ->registered_rings
  io_uring: don't set REQ_F_COMPLETE_INLINE in tw
  io_uring: never defer-complete multi-apoll
  io_uring: kill REQ_F_COMPLETE_INLINE
  io_uring: refactor io_req_task_complete()
  io_uring: don't inline io_put_kbuf
  io_uring: remove check_cq checking from hot paths
  io_uring: pass poll_find lock back
  io_uring: clean up io_try_cancel
  io_uring: limit number hash 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-wq.h              |   1 +
 io_uring/io_uring.c           | 145 +++++++++++-----------
 io_uring/io_uring.h           |  17 +++
 io_uring/io_uring_types.h     | 108 +++++++++--------
 io_uring/kbuf.c               |  33 +++++
 io_uring/kbuf.h               |  38 +-----
 io_uring/poll.c               | 219 +++++++++++++++++++++++++---------
 io_uring/poll.h               |   3 +-
 io_uring/rsrc.c               |   9 +-
 io_uring/tctx.c               |  36 ++++--
 io_uring/tctx.h               |   7 +-
 io_uring/timeout.c            |   3 +-
 16 files changed, 416 insertions(+), 246 deletions(-)