On Wed 04-05-16 23:39:14, Joonsoo Kim wrote: > 2016-05-04 17:53 GMT+09:00 Michal Hocko <[email protected]>: > > On Wed 04-05-16 15:01:24, Joonsoo Kim wrote: > >> On Wed, Apr 20, 2016 at 03:47:25PM -0400, Michal Hocko wrote: > > [...] > > > > Please try to trim your responses it makes it much easier to follow the > > discussion > > Okay. > > >> > +static inline bool > >> > +should_compact_retry(unsigned int order, enum compact_result > >> > compact_result, > >> > + enum migrate_mode *migrate_mode, > >> > + int compaction_retries) > >> > +{ > >> > + if (!order) > >> > + return false; > >> > + > >> > + /* > >> > + * compaction considers all the zone as desperately out of memory > >> > + * so it doesn't really make much sense to retry except when the > >> > + * failure could be caused by weak migration mode. > >> > + */ > >> > + if (compaction_failed(compact_result)) { > >> > >> IIUC, this compaction_failed() means that at least one zone is > >> compacted and failed. This is not same with your assumption in the > >> comment. If compaction is done and failed on ZONE_DMA, it would be > >> premature decision. > > > > Not really, because if other zones are making some progress then their > > result will override COMPACT_COMPLETE > > Think about the situation that DMA zone fails to compact and > the other zones are deferred or skipped. In this case, COMPACT_COMPLETE > will be returned as a final result and should_compact_retry() return false. > I don't think that it means all the zones are desperately out of memory.
But that would mean that the ZONE_DMA would be eligible for compaction, no? And considering the watermark check this zone should COMPACT_SKIP for most allocation request. Or am I missing something? -- Michal Hocko SUSE Labs
