On Fri, Jul 01, 2016 at 09:01:17PM +0100, Mel Gorman wrote: > Direct reclaim iterates over all zones in the zonelist and shrinking them > but this is in conflict with node-based reclaim. In the default case, > only shrink once per node. > > Signed-off-by: Mel Gorman <mgor...@techsingularity.net> > Acked-by: Johannes Weiner <han...@cmpxchg.org> > Acked-by: Vlastimil Babka <vba...@suse.cz> > --- > mm/vmscan.c | 19 +++++++++++-------- > 1 file changed, 11 insertions(+), 8 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index b524d3b72527..34656173a670 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2552,14 +2552,6 @@ static inline bool compaction_ready(struct zone *zone, > int order, int classzone_ > * try to reclaim pages from zones which will satisfy the caller's allocation > * request. > * > - * We reclaim from a zone even if that zone is over high_wmark_pages(zone). > - * Because: > - * a) The caller may be trying to free *extra* pages to satisfy a > higher-order > - * allocation or > - * b) The target zone may be at high_wmark_pages(zone) but the lower zones > - * must go *over* high_wmark_pages(zone) to satisfy the `incremental min' > - * zone defense algorithm. > - * > * If a zone is deemed to be full of pinned pages then just give it a light > * scan then give up on it. > */ > @@ -2571,6 +2563,7 @@ static void shrink_zones(struct zonelist *zonelist, > struct scan_control *sc) > unsigned long nr_soft_scanned; > gfp_t orig_mask; > enum zone_type classzone_idx; > + pg_data_t *last_pgdat = NULL; > > /* > * If the number of buffer_heads in the machine exceeds the maximum > @@ -2600,6 +2593,16 @@ static void shrink_zones(struct zonelist *zonelist, > struct scan_control *sc) > classzone_idx--; > > /* > + * Shrink each node in the zonelist once. If the zonelist is > + * ordered by zone (not the default) then a node may be > + * shrunk multiple times but in that case the user prefers > + * lower zones being preserved > + */ > + if (zone->zone_pgdat == last_pgdat) > + continue; > + last_pgdat = zone->zone_pgdat; > + > + /*
After this change, compaction_ready() which uses zone information would be called with highest zone in node. So, if some lower zone in that node is compaction-ready, we cannot stop the reclaim. Thanks.
