On 2016.08.22 at 13:13 +0200, Michal Hocko wrote: > 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. I now recall. It was an issue with CONFIG_TRANSPARENT_HUGEPAGE, so I disabled that option. This then de-selected CONFIG_COMPACTION... -- Markus -- 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>