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
