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.
