Jens Axboe <axboe@xxxxxxxxx> writes: > The submission queue (SQ) and completion queue (CQ) rings are shared > between the application and the kernel. This eliminates the need to > copy data back and forth to submit and complete IO. We use the same > structures as the old aio interface. The SQ rings are indexes into a > struct iocb array, like we would submit through io_submit(), and the > CQ rings are struct io_event, like we would pass in (and copy back) > from io_getevents(). > > A new system call is added for this, io_ring_enter(). This system call > submits IO that is stored in the SQ ring, and/or completes IO and stores > the results in the CQ ring. Hence it's possible to both complete and > submit IO in a single system call. > > For IRQ driven IO, an application only needs to enter the kernel for > completions if it wants to wait for them to occur. It looks like the memory for the submission and completion queues is not migratable (scq rings are non-migratory! [1]). Maybe you should use the aio pseudofs for allocations, like is done with the original aio ring. I realize that would change the api... -Jeff [1] https://www.youtube.com/watch?v=liIlW-ovx0Y
