https://bugzilla.kernel.org/show_bug.cgi?id=208827 --- Comment #25 from Jens Axboe (axboe@xxxxxxxxx) --- On 8/12/20 9:24 AM, Jeff Moyer wrote: > Jens Axboe <axboe@xxxxxxxxx> writes: > >> Yes, it would ideally wait, or at least trigger on the last one. I'll >> see if I can improve that. For any of my testing, the amount of >> triggered short reads is minimal. For the verify case that we just >> ran, we're talking 8-12 ios out of 820 thousand, or 0.001% of them. >> So nothing that makes a performance difference in practical terms, >> though it would be nice to not hand back short reads if we can avoid >> it. Not for performance reasons, but for usage reasons. > > I think you could make the case that handing back a short read is a > bug (unless RWF_NOWAIT was specified, of course). At the very least, > it violates the principle of least surprise, and the fact that it > happens infrequently actually makes it a worse problem when it comes > to debugging. It's definitely on my list to ensure that we handle the somewhat expected case by just retrying it internally, because I do agree that it can be surprising. FWIW, this isn't a change with 5.9-rc, io_uring has always potentially short buffered reads when when the io-wq offload was done. While it may happen infrequently with this specific test case, others can trigger it more often. -- You are receiving this mail because: You are watching the assignee of the bug.
