On Sat, Jul 30, 2016 at 04:36:17PM -0700, Linus Torvalds wrote: > So? Aren't they in the same cacheline? Yes (unless lockdep map is stuck in between, in which case we are slow as hell anyway). > We've tried very hard to pack all those initial elements next to each other. > > The first-order approximation is that number of cacheline accesses > matter. And then the second order is to make code small and avoid > extra instructions. > > As far as I can tell, your change doesn't actually help the cacheline > accesses, and it makes the code bigger and have extra instructions. So > it doesn't appear to improve anything, and it does make things worse. > > But numbers talk, bullshit walks. If you have numbers to show > something different, that trumps my looking at code. I'll profile and post the results; not today, though - it's not urgent anyway, and right now I wouldn't trust my ability to do anything other than crawl to the bed and hopefully get some sleep (RDU -> BOS -> RDU, on top of 4 hours of sleep tonight and bloody two hours of delay in plane on the way back due to bad weather; picking the younger kid from summer STEM camp had been... interesting, for the lack of adequate printable words) -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
