On Mon 22-08-16 13:01:13, Markus Trippelsdorf wrote: > On 2016.08.22 at 12:56 +0200, Michal Hocko wrote: > > On Mon 22-08-16 12:16:14, Markus Trippelsdorf wrote: > > > On 2016.08.22 at 11:32 +0200, Michal Hocko wrote: > > > > [1] http://lkml.kernel.org/r/20160731051121.GB307@x4 > > > > > > For the report [1] above: > > > > > > markus@x4 linux % cat .config | grep CONFIG_COMPACTION > > > # CONFIG_COMPACTION is not set > > > > Hmm, without compaction and a heavy fragmentation then I am afraid we > > cannot really do much. What is the reason to disable compaction in the > > first place? > > I don't recall. Must have been some issue in the past. I will re-enable > the option. Well, without the compaction there is no source of high order pages at all. You can only reclaim and hope that some of the reclaimed pages will find its buddy on the list and form the higher order page. This can take for ever. We used to have the lumpy reclaim and that could help but this is long gone. I do not think we can really sanely optimize for high-order heavy loads without COMPACTION sanely. At least not without reintroducing lumpy reclaim or something similar. To be honest I am even not sure which configurations should disable compaction - except for really highly controlled !mmu or other one purpose systems. -- Michal Hocko 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>