On 14/05/2020 18:53, Jens Axboe wrote: > On 5/14/20 9:37 AM, Pavel Begunkov wrote: > Hmm yes good point, it should work pretty easily, barring the use cases > that do IRQ complete. But that was also a special case with the other > cache. > >> BTW, there will be a lot of problems to make either work properly with >> IORING_FEAT_SUBMIT_STABLE. > > How so? Once the request is setup, any state should be retained there. If a late alloc fails (e.g. in __io_queue_sqe()), you'd need to file a CQE with an error. If there is no place in CQ, to postpone the completion it'd require an allocated req. Of course it can be dropped, but I'd prefer to have strict guarantees. That's the same reason, I have a patch stashed, that grabs links from SQ atomically (i.e. take all SQEs of a link or none). -- Pavel Begunkov
