On Tue, Aug 20, 2013 at 03:59:36PM +0900, Fernando Luis Vázquez Cao wrote: > That said, if deemed acceptable, option A is the one I would > choose.
Right, so I think we can do A without much extra cost mostly because we already have 2 atomics in the io_schedule() path. If we replace those two atomic operations with locks and modify nr_iowait and the other stats under the same lock, and ensure all those variables (including the lock) live in the same cacheline we should have the same cost we have now. Of course, if we can get away with completely removing all of that (which I think Arjan suggested was a real possibility) then that would be ever so much better still :-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
