On 08/16/2016 07:58 AM, Joonsoo Kim wrote:
--- a/mm/compaction.c +++ b/mm/compaction.c @@ -1644,6 +1644,8 @@ static enum compact_result compact_zone_order(struct zone *zone, int order, .alloc_flags = alloc_flags, .classzone_idx = classzone_idx, .direct_compaction = true, + .whole_zone = (prio == COMPACT_PRIO_SYNC_FULL), + .ignore_skip_hint = (prio == COMPACT_PRIO_SYNC_FULL) }; INIT_LIST_HEAD(&cc.freepages); INIT_LIST_HEAD(&cc.migratepages); @@ -1689,7 +1691,8 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order, ac->nodemask) { enum compact_result status; - if (compaction_deferred(zone, order)) { + if (prio > COMPACT_PRIO_SYNC_FULL + && compaction_deferred(zone, order)) { rc = max_t(enum compact_result, COMPACT_DEFERRED, rc); continue;Could we provide prio to compaction_deferred() and do the decision in that that function? BTW, in kcompactd, compaction_deferred() is checked but .ignore_skip_hint=true. Is there any reason? If we can remove compaction_deferred() for kcompactd, we can check .ignore_skip_hint to determine if defer is needed or not.
I don't want to change kcompactd right now, as the current series seems to help against premature OOMs. But I'll revisit it later.
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