[PATCH v2 0/3] aio-posix: keep aio_notify_me disabled during polling

[Stefan Hajnoczi <stefanha@redhat.com>]

v2:
 * Added smp_mb() in aio_notify_accept() [Paolo]
 * Added comments about memory barrier pairing [Paolo]
 * Eliminated extra aio_compute_timeout() before calling ppoll()

This patch series eliminates ctx->notifier EventNotifier activity when
aio_poll() is in polling mode. There is no need to use the EventNotifier since
a polling handler can detect that aio_notify() has been called by monitoring a
field in memory instead.

Optimizing out the EventNotifier calls improves null-co random read 4KB
iodepth=1 IOPS by 18%.

I have not modified docs/spin/aio_notify*.promela because I'm not familiar with
the SPIN model checker.

Stefan Hajnoczi (3):
  async: rename event_notifier_dummy_cb/poll()
  async: always set ctx->notified in aio_notify()
  aio-posix: keep aio_notify_me disabled during polling

 util/aio-posix.c | 59 +++++++++++++++++++++++++-----------------------
 util/async.c     | 36 ++++++++++++++++++-----------
 2 files changed, 54 insertions(+), 41 deletions(-)

-- 
2.26.2