On Wed, Oct 30, 2024 at 11:08:16AM +0800, Ming Lei wrote: > On Tue, Oct 29, 2024 at 08:43:39PM -0600, Jens Axboe wrote: ... > > You could avoid the OP dependency with just a flag, if you really wanted > > to. But I'm not sure it makes a lot of sense. And it's a hell of a lot > > Yes, IO_LINK won't work for submitting multiple IOs concurrently, extra > syscall makes application too complicated, and IO latency is increased. > > > simpler than the sqe group scheme, which I'm a bit worried about as it's > > a bit complicated in how deep it needs to go in the code. This one > > stands alone, so I'd strongly encourage we pursue this a bit further and > > iron out the kinks. Maybe it won't work in the end, I don't know, but it > > seems pretty promising and it's soooo much simpler. > > If buffer register and lookup are always done in ->prep(), OP dependency > may be avoided. Even all buffer register and lookup are done in ->prep(), OP dependency still can't be avoided completely, such as: 1) two local buffers for sending to two sockets 2) group 1: IORING_OP_LOCAL_KBUF1 & [send(sock1), send(sock2)] 3) group 2: IORING_OP_LOCAL_KBUF2 & [send(sock1), send(sock2)] group 1 and group 2 needs to be linked, but inside each group, the two sends may be submitted in parallel. Thanks, Ming
