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* [PATCH 0/2] io_uring: add a CQ ring flag to enable/disable eventfd notification
@ 2020-05-15 10:54 Stefano Garzarella
  2020-05-15 10:54 ` [PATCH 1/2] io_uring: add 'cq_flags' field for the CQ ring Stefano Garzarella
                   ` (2 more replies)
  0 siblings, 3 replies; 8+ messages in thread
From: Stefano Garzarella @ 2020-05-15 10:54 UTC (permalink / raw)
  To: Jens Axboe; +Cc: io-uring, linux-kernel, linux-fsdevel, Alexander Viro

The first patch adds the new 'cq_flags' field for the CQ ring. It
should be written by the application and read by the kernel.

The second patch adds a new IORING_CQ_NEED_WAKEUP flag that can be
used by the application to enable/disable eventfd notifications.

I'm not sure the name is the best one, an alternative could be
IORING_CQ_NEED_EVENT.

This feature can be useful if the application are using eventfd to be
notified when requests are completed, but they don't want a notification
for every request.
Of course the application can already remove the eventfd from the event
loop, but as soon as it adds the eventfd again, it will be notified,
even if it has already handled all the completed requests.

The most important use case is when the registered eventfd is used to
notify a KVM guest through irqfd and we want a mechanism to
enable/disable interrupts.

I also extended liburing API and added a test case here:
https://github.com/stefano-garzarella/liburing/tree/eventfd-disable

Stefano Garzarella (2):
  io_uring: add 'cq_flags' field for the CQ ring
  io_uring: add IORING_CQ_NEED_WAKEUP to the CQ ring flags

 fs/io_uring.c                 | 17 ++++++++++++++++-
 include/uapi/linux/io_uring.h |  9 ++++++++-
 2 files changed, 24 insertions(+), 2 deletions(-)

-- 
2.25.4


^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2020-05-15 15:26 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2020-05-15 10:54 [PATCH 0/2] io_uring: add a CQ ring flag to enable/disable eventfd notification Stefano Garzarella
2020-05-15 10:54 ` [PATCH 1/2] io_uring: add 'cq_flags' field for the CQ ring Stefano Garzarella
2020-05-15 10:54 ` [PATCH 2/2] io_uring: add IORING_CQ_NEED_WAKEUP to the CQ ring flags Stefano Garzarella
2020-05-15 14:24 ` [PATCH 0/2] io_uring: add a CQ ring flag to enable/disable eventfd notification Jens Axboe
2020-05-15 14:34   ` Stefano Garzarella
2020-05-15 15:13     ` Jens Axboe
2020-05-15 15:24       ` Stefano Garzarella
2020-05-15 15:26         ` Jens Axboe

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