On Wed, Oct 27, 2010 at 06:41:38PM +0200, Andrea Arcangeli wrote: > Hi, > > > <SNIP> > > [...] > > this rejects on THP code, lumpy is unusable with hugepages, it grinds > the system to an halt, and there's no reason to let it survive. Lumpy > is like compaction done with an hammer while blindfolded. > The series drastically limits the level of hammering lumpy does to the system. I'm currently keeping it alive because lumpy reclaim has received a lot more testing than compaction has. While I ultimately see it going away, I am resisting it being deleted until compaction has been around for a few releases. > I don't know why community insists on improving lumpy when it has to > be removed completely, especially now that we have memory compaction. > Simply because it has been tested and even with compaction there were cases envisoned where it would be used - low memory or when compaction is not configured in for example. The ideal is that compaction is used until lumpy is necessary although this applies more to the static resizing of the huge page pool than THP which I'd expect to backoff without using lumpy reclaim i.e. fail the allocation rather than using lumpy reclaim. > I'll keep deleting on my tree... > > I hope lumpy work stops here and that it goes away whenever THP is > merged. > Uhhh, I have one more modification in mind when lumpy is involved and it's to relax the zone watermark slightly to only obey up to PAGE_ALLOC_COSTLY_ORDER. At the moment, it is freeing more pages than are necessary to satisfy an allocation request and hits the system harder than it should. Similar logic should apply to compaction. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>