On Fri, Apr 05, 2019 at 05:36:32PM -0600, Keith Busch wrote: > On Fri, Apr 5, 2019 at 5:04 PM Jens Axboe <axboe@xxxxxxxxx> wrote: > > Looking at current peak testing, I've got around 1.2% in queue enter > > and exit. It's definitely not free, hence my question. Probably safe > > to assume that we'll double that cycle counter, per IO. > > Okay, that's not negligible at all. I don't know of a faster reference > than the percpu_ref, but that much overhead would have to rule out > having a per hctx counter. Can we just replace queue_enter/exit with the per-hctx reference entirely?
