[PATCH v2 00/13] optimise registered buffer/file updates

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

The patchset optimises registered files and buffers updates / removals,
The rsrc-update-bench test showes 11x improvement (1040K -> 11468K
updates / sec). It also improves latency by eliminating rcu grace
period waiting and bouncing it to another worker, and reduces
memory footprint by removing percpu refs.

That's quite important for apps updating files/buffers with medium or
higher frequency as updates are slow and expensive, and it currently
takes quite a number of IO requests per update to make using fixed
files/buffers worthwhile.

Another upside is that it makes it simpler, patch 9 removes very
convoluted synchronisation via flush_delayed_work() from the quiesce
path.

v2: rebase, add patches 12 and 13 to remove the last pair atomics out
    of the path and to limit caching.

Pavel Begunkov (13):
  io_uring/rsrc: use non-pcpu refcounts for nodes
  io_uring/rsrc: keep cached refs per node
  io_uring: don't put nodes under spinlocks
  io_uring: io_free_req() via tw
  io_uring/rsrc: protect node refs with uring_lock
  io_uring/rsrc: kill rsrc_ref_lock
  io_uring/rsrc: rename rsrc_list
  io_uring/rsrc: optimise io_rsrc_put allocation
  io_uring/rsrc: don't offload node free
  io_uring/rsrc: cache struct io_rsrc_node
  io_uring/rsrc: add lockdep sanity checks
  io_uring/rsrc: optimise io_rsrc_data refcounting
  io_uring/rsrc: add custom limit for node caching

 include/linux/io_uring_types.h |   8 +-
 io_uring/alloc_cache.h         |   6 +-
 io_uring/io_uring.c            |  54 ++++++----
 io_uring/rsrc.c                | 176 ++++++++++++---------------------
 io_uring/rsrc.h                |  58 +++++------
 5 files changed, 136 insertions(+), 166 deletions(-)

-- 
2.39.1