On 12/16/19 9:47 AM, Pavel Begunkov wrote: > On 16/12/2019 00:33, Jens Axboe wrote: >> On 12/15/19 8:48 AM, Pavel Begunkov wrote: >>> On 15/12/2019 08:42, Jens Axboe wrote: >>>> On 12/14/19 11:43 AM, Jens Axboe wrote: >>>>> On 12/14/19 7:53 AM, Pavel Begunkov wrote: >>>>>> There is no reliable way to submit and wait in a single syscall, as >>>>>> io_submit_sqes() may under-consume sqes (in case of an early error). >>>>>> Then it will wait for not-yet-submitted requests, deadlocking the user >>>>>> in most cases. >>>>>> >>>>>> In such cases adjust min_complete, so it won't wait for more than >>>>>> what have been submitted in the current call to io_uring_enter(). It >>>>>> may be less than totally in-flight including previous submissions, >>>>>> but this shouldn't do harm and up to a user. >>>>> >>>>> Thanks, applied. >>>> >>>> This causes a behavioral change where if you ask to submit 1 but >>>> there's nothing in the SQ ring, then you would get 0 before. Now >>>> you get -EAGAIN. This doesn't make a lot of sense, since there's no >>>> point in retrying as that won't change anything. >>>> >>>> Can we please just do something like the one I sent, instead of trying >>>> to over-complicate it? >>>> >>> >>> Ok, when I get to a compiler. >> >> Great, thanks. BTW, I noticed when a regression test failed. >> > > Yeah, I properly tested only the first one. Clearly, not as easy as > I thought, and there were more to consider. > > I sent the next version, but that's odd basically taking your code. > Probably, it would have been easier for you to just commit it yourself. Nah, I'll keep you attribution, the hard part is finding/spotting the issue, not the actual fix. I've applied v4, thanks Pavel! -- Jens Axboe
