On Fri, Jul 22, 2011 at 02:57:12PM +0200, Peter Zijlstra wrote: > On Thu, 2011-07-21 at 17:28 +0100, Mel Gorman wrote: > > Assuming that flusher threads will always write back dirty pages promptly > > then it is always faster for reclaimers to wait for flushers. This patch > > prevents kswapd writing back any filesystem pages. > > That is a somewhat sort changelog for such a big assumption ;-) > That is an understatement but the impact of the patch is discussed in detail in the leader. On NUMA, this patch has a negative impact so I put no effort into the changelog. The patch is part of the series because it was specifically asked for. > I think it can use a few extra words to explain the need to clean pages > from @zone vs writeback picks whatever fits best on disk and how that > works out wrt the assumption. > At the time of writing the changelog, I knew that flushers were not finding pages from the correct zones quickly enough in the NUMA usecase. The changelog documents the assumptions testing shows them to be false. > What requirements does this place on writeback and how does it meet > them. It places a requirement on writeback to prioritise pages from zones under memory pressure. It doesn't meet them. I mention in the leader that I think patch 8 should be dropped which is why the changelog sucks. -- Mel Gorman SUSE Labs -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>