[PATCH RFC 5.13 0/2] adaptive sqpoll and its wakeup optimization

[Hao Xu <haoxu@linux.alibaba.com>]

patch 1/2 provides a new option to set up sq_thread_idle in nanosecond
granularity.
patch 2/2 is to cut down IO latency when sqthread is waking up.

This is a RFC, especially 2/2. There may be more works to do, like add
a REGISTER OP to allow applications to adjust sq_thread_idle, since it
may experience both high IO pressure and low IO pressure. And in low IO
pressure, patch 1/2 saves cpu resource while keeping a reasonable
latency. liburing tweak is ready as well, but currently I'd like to just
post this for comments.

Hao Xu (2):
  io_uring: add support for ns granularity of io_sq_thread_idle
  io_uring: submit sqes in the original context when waking up sqthread

 fs/io_uring.c                 | 88 ++++++++++++++++++++++++++++++++-----------
 include/uapi/linux/io_uring.h |  4 +-
 2 files changed, 70 insertions(+), 22 deletions(-)

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1.8.3.1