On Mon, Jan 27, 2020 at 11:46:34AM -0700, Jens Axboe wrote: > On 1/27/20 11:25 AM, Stefano Garzarella wrote: > > On Mon, Jan 27, 2020 at 09:32:43AM -0700, Jens Axboe wrote: > >> On 1/27/20 9:17 AM, Stefano Garzarella wrote: > >>> Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx> > >> > >> You're not reaping CQ events, and hence you overflow the ring. Once > >> overflown, an attempt to submit new IO will returns in a -16/-EBUSY > >> return value. This is io_uring telling you that it won't submit more > >> IO until you've emptied the completion ring so io_uring can flush > >> the overflown entries to the ring. > > > > How can I reaping CQ events? (I was hoping the epoll would help me with that) > > > > What I'm seeing is that the producer (EPOLLOUT) can fill the SQ without issues, > > the consumer (read()) is receiving all the buffers produced, but the thread > > that frees the buffers (EPOLLIN) is not woken up. > > > > I tried to set a timeout to the epoll_wait(), but the io_uring_peek_cqe() > > returns -EAGAIN. > > > > If I'm using a ring with 16 entries, it seems to work better, but > > sometimes I lose events and the thread that frees the buffer doesn't wake up. > > > > Maybe I'm missing something... > > OK, so that helps in terms of understanding the issue you are seeing with > it. I'll take a look at this, but it'll probably be a few days. You can Sure, take your time! > try and enable tracing, I see events completed just fine. Maybe a race > with your epoll wait and event reaping? Could be. I'll try to investigate better enabling the tracing! Thanks, Stefano
