NeilBrown <neilb@xxxxxxx> writes: > On Wed, 8 Jun 2011 16:00:45 +0900 Namhyung Kim <namhyung@xxxxxxxxx> wrote: > >> If @conf->far_offset > 0, there is only 1 stripe so that we can treat >> the array same as 'near' arrays. Furthermore we could calculate new >> distance from the previous position even for the real 'far' array >> cases if the position of given disk is already in the lowest stripe. >> > I agree that it still make sense to to balancing if far_offset != 0. > However there is absolutely no point in your change to the calculation of > new_distance. > You only wont new_distance to contain a distance from head position if we > want to choose the device with the 'closest' head. But we don't. We want to > choose the device were the data is closest to the start of the device. So > the current value for new_distance is correct. > Still can't understand why we choose the closest-to-the-start disk in case we could have possible sequencial access on other disk. Probably because of the lack of my understanding how md/disk works :( > If you would like to resubmit with just the first change I'll happily apply > the patch. > OK. Will do that right soon. > If you have performed some tests and can demonstrate some cases where this > makes something faster, and can show us the results of those tests, I would > be even more happy!!! > I wish I could. :) However, unfortunately, I don't have such a real system to test on. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
