On Tue, Jul 20, 2010 at 03:10:49PM +0100, Mel Gorman wrote: > On Tue, Jul 20, 2010 at 12:48:39AM +0200, Johannes Weiner wrote: > > On Mon, Jul 19, 2010 at 03:37:37PM +0100, Mel Gorman wrote: > > > although the latter can get disabled too. Deleting the magic is an > > > option which would trade IO efficiency for power efficiency but my > > > current thinking is laptop mode preferred reduced power. > > > > Maybe couple your wakeup with sc->may_writepage? It is usually false > > for laptop_mode but direct reclaimers enable it at one point in > > do_try_to_free_pages() when it scanned more than 150% of the reclaim > > target, so you could use existing disk spin-up points instead of > > introducing new ones or disabling the heuristics in laptop mode. > > > > How about the following? > > if (nr_dirty && sc->may_writepage) > wakeup_flusher_threads(laptop_mode ? 0 : > nr_dirty + nr_dirty / 2); > > > 1. Wakup flusher threads if dirty pages are encountered > 2. For direct reclaim, only wake them up if may_writepage is set > indicating that the system is ready to spin up disks and start > reclaiming > 3. In laptop_mode, flush everything to reduce future spin-ups Sounds like the sanest approach to me. Thanks. Hannes -- 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
