On Wed, Jul 09, 2014 at 09:13:05AM +0100, Mel Gorman wrote: > zone->pages_scanned is a write-intensive cache line during page reclaim > and it's also updated during page free. Move the counter into vmstat to > take advantage of the per-cpu updates and do not update it in the free > paths unless necessary. > > On a small UMA machine running tiobench the difference is marginal. On a > 4-node machine the overhead is more noticable. Note that automatic NUMA > balancing was disabled for this test as otherwise the system CPU overhead > is unpredictable. > > 3.16.0-rc3 3.16.0-rc3 3.16.0-rc3 > vanillarearrange-v5 vmstat-v5 > User 746.94 759.78 774.56 > System 65336.22 58350.98 32847.27 > Elapsed 27553.52 27282.02 27415.04 > > Note that the overhead reduction will vary depending on where exactly > pages are allocated and freed. > > Signed-off-by: Mel Gorman <mgorman@xxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>