[PATCH v2 -mm 3/3] mm: only defer compaction for failed order and higher
From: Rik van Riel <hidden>
Date: 2012-01-24 18:24:10
Also in:
lkml
Subsystem:
memory management, memory management - core, memory management - mglru (multi-gen lru), memory management - page allocator, memory management - reclaim, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Vlastimil Babka, Johannes Weiner, Linus Torvalds
Currently a failed order-9 (transparent hugepage) compaction can lead to memory compaction being temporarily disabled for a memory zone. Even if we only need compaction for an order 2 allocation, eg. for jumbo frames networking. The fix is relatively straightforward: keep track of the order at which compaction failed to create a free memory area. Only defer compaction at that order and higher, while letting compaction go through for lower orders. Signed-off-by: Rik van Riel <redacted> --- include/linux/compaction.h | 14 ++++++++++---- include/linux/mmzone.h | 1 + mm/compaction.c | 11 ++++++++++- mm/page_alloc.c | 6 ++++-- mm/vmscan.c | 2 +- 5 files changed, 26 insertions(+), 8 deletions(-)
diff --git a/include/linux/compaction.h b/include/linux/compaction.h
index 7a9323a..51a90b7 100644
--- a/include/linux/compaction.h
+++ b/include/linux/compaction.h@@ -34,20 +34,26 @@ extern unsigned long compaction_suitable(struct zone *zone, int order); * allocation success. 1 << compact_defer_limit compactions are skipped up * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT */ -static inline void defer_compaction(struct zone *zone) +static inline void defer_compaction(struct zone *zone, int order) { zone->compact_considered = 0; zone->compact_defer_shift++; + if (order < zone->compact_order_failed) + zone->compact_order_failed = order; + if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT) zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT; } /* Returns true if compaction should be skipped this time */ -static inline bool compaction_deferred(struct zone *zone) +static inline bool compaction_deferred(struct zone *zone, int order) { unsigned long defer_limit = 1UL << zone->compact_defer_shift; + if (order < zone->compact_order_failed) + return false; + /* Avoid possible overflow */ if (++zone->compact_considered > defer_limit) zone->compact_considered = defer_limit;
@@ -73,11 +79,11 @@ static inline unsigned long compaction_suitable(struct zone *zone, int order) return COMPACT_SKIPPED; } -static inline void defer_compaction(struct zone *zone) +static inline void defer_compaction(struct zone *zone, int order) { } -static inline bool compaction_deferred(struct zone *zone) +static inline bool compaction_deferred(struct zone *zone, int order) { return 1; }
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 650ba2f..dff7115 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h@@ -365,6 +365,7 @@ struct zone { */ unsigned int compact_considered; unsigned int compact_defer_shift; + int compact_order_failed; #endif ZONE_PADDING(_pad1_)
diff --git a/mm/compaction.c b/mm/compaction.c
index 51ece75..e8cff81 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c@@ -673,9 +673,18 @@ static int __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc) INIT_LIST_HEAD(&cc->freepages); INIT_LIST_HEAD(&cc->migratepages); - if (cc->order < 0 || !compaction_deferred(zone)) + if (cc->order < 0 || !compaction_deferred(zone, cc->order)) compact_zone(zone, cc); + if (cc->order > 0) { + int ok = zone_watermark_ok(zone, cc->order, + low_wmark_pages(zone), 0, 0); + if (ok && cc->order > zone->compact_order_failed) + zone->compact_order_failed = cc->order + 1; + else if (!ok && cc->sync) + defer_compaction(zone, cc->order); + } + VM_BUG_ON(!list_empty(&cc->freepages)); VM_BUG_ON(!list_empty(&cc->migratepages)); }
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0027d8f..cd617d9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c@@ -1990,7 +1990,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order, if (!order) return NULL; - if (compaction_deferred(preferred_zone)) { + if (compaction_deferred(preferred_zone, order)) { *deferred_compaction = true; return NULL; }
@@ -2012,6 +2012,8 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order, if (page) { preferred_zone->compact_considered = 0; preferred_zone->compact_defer_shift = 0; + if (order >= preferred_zone->compact_order_failed) + preferred_zone->compact_order_failed = order + 1; count_vm_event(COMPACTSUCCESS); return page; }
@@ -2028,7 +2030,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order, * defer if the failure was a sync compaction failure. */ if (sync_migration) - defer_compaction(preferred_zone); + defer_compaction(preferred_zone, order); cond_resched(); }
diff --git a/mm/vmscan.c b/mm/vmscan.c
index fa17794..5d65991 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c@@ -2199,7 +2199,7 @@ static inline bool compaction_ready(struct zone *zone, struct scan_control *sc) * If compaction is deferred, reclaim up to a point where * compaction will have a chance of success when re-enabled */ - if (compaction_deferred(zone)) + if (compaction_deferred(zone, sc->order)) return watermark_ok; /* If compaction is not ready to start, keep reclaiming */ --
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