On Wed, 2018-05-09 at 09:18 -0600, Jens Axboe wrote: > On 5/8/18 10:11 PM, Mike Galbraith wrote: > > On Tue, 2018-05-08 at 19:09 -0600, Jens Axboe wrote: > >> > >> Alright, I managed to reproduce it. What I think is happening is that > >> BFQ is limiting the inflight case to something less than the wake > >> batch for sbitmap, which can lead to stalls. I don't have time to test > >> this tonight, but perhaps you can give it a go when you are back at it. > >> If not, I'll try tomorrow morning. > >> > >> If this is the issue, I can turn it into a real patch. This is just to > >> confirm that the issue goes away with the below. > > > > Confirmed. Impressive high speed bug stomping. > > Well, that's good news. Can I get you to try this patch? Sure thing. The original hang (minus provocation patch) being annoyingly non-deterministic, this will (hopefully) take a while. -Mike
