On 7/10/20 7:10 AM, Christoph Hellwig wrote: > On Fri, Jul 10, 2020 at 12:35:43AM +0530, Kanchan Joshi wrote: >> Append required special treatment (conversion for sector to bytes) for io_uring. >> And we were planning a user-space wrapper to abstract that. >> >> But good part (as it seems now) was: append result went along with cflags at >> virtually no additional cost. And uring code changes became super clean/minimal >> with further revisions. >> While indirect-offset requires doing allocation/mgmt in application, >> io-uring submission >> and in completion path (which seems trickier), and those CQE flags >> still get written >> user-space and serve no purpose for append-write. > > I have to say that storing the results in the CQE generally make > so much more sense. I wonder if we need a per-fd "large CGE" flag > that adds two extra u64s to the CQE, and some ops just require this > version. I have been pondering the same thing, we could make certain ops consume two CQEs if it makes sense. It's a bit ugly on the app side with two different CQEs for a request, though. We can't just treat it as a large CQE, as they might not be sequential if we happen to wrap. But maybe it's not too bad. -- Jens Axboe
