mbox series

[v3,0/3] aio-posix: keep aio_notify_me disabled during polling

Message ID 20200806131802.569478-1-stefanha@redhat.com
Headers show
Series aio-posix: keep aio_notify_me disabled during polling | expand

Message

Stefan Hajnoczi Aug. 6, 2020, 1:17 p.m. UTC 
v3:
 * Use smp_wmb() in aio_notify_accept() [Paolo]
 * Flatten if statement in aio_poll() [Paolo]

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 | 47 +++++++++++++++++++++++++----------------------
 util/async.c     | 36 +++++++++++++++++++++++-------------
 2 files changed, 48 insertions(+), 35 deletions(-)

-- 
2.26.2