From 7be62de99adcab4449d416977b4274985c5fe023 Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Wed, 21 Mar 2012 16:33:52 -0700 Subject: vmscan: kswapd carefully call compaction With CONFIG_COMPACTION enabled, kswapd does not try to free contiguous free pages, even when it is woken for a higher order request. This could be bad for eg. jumbo frame network allocations, which are done from interrupt context and cannot compact memory themselves. Higher than before allocation failure rates in the network receive path have been observed in kernels with compaction enabled. Teach kswapd to defragment the memory zones in a node, but only if required and compaction is not deferred in a zone. [akpm@linux-foundation.org: reduce scope of zones_need_compaction] Signed-off-by: Rik van Riel Acked-by: Mel Gorman Cc: Andrea Arcangeli Cc: Johannes Weiner Cc: Minchan Kim Cc: KOSAKI Motohiro Cc: Hillf Danton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/compaction.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux/compaction.h') diff --git a/include/linux/compaction.h b/include/linux/compaction.h index bb2bbdbe5464..7a9323aef4a3 100644 --- a/include/linux/compaction.h +++ b/include/linux/compaction.h @@ -23,6 +23,7 @@ extern int fragmentation_index(struct zone *zone, unsigned int order); extern unsigned long try_to_compact_pages(struct zonelist *zonelist, int order, gfp_t gfp_mask, nodemask_t *mask, bool sync); +extern int compact_pgdat(pg_data_t *pgdat, int order); extern unsigned long compaction_suitable(struct zone *zone, int order); /* Do not skip compaction more than 64 times */ @@ -62,6 +63,11 @@ static inline unsigned long try_to_compact_pages(struct zonelist *zonelist, return COMPACT_CONTINUE; } +static inline int compact_pgdat(pg_data_t *pgdat, int order) +{ + return COMPACT_CONTINUE; +} + static inline unsigned long compaction_suitable(struct zone *zone, int order) { return COMPACT_SKIPPED; -- cgit v1.2.3 From aff622495c9a0b56148192e53bdec539f5e147f2 Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Wed, 21 Mar 2012 16:33:52 -0700 Subject: vmscan: only defer compaction for failed order and higher 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 highest order at which compaction is succeeding, and only defer compaction for orders at which compaction is failing. Signed-off-by: Rik van Riel Cc: Andrea Arcangeli Acked-by: Mel Gorman Cc: Johannes Weiner Cc: Minchan Kim Cc: KOSAKI Motohiro Cc: Hillf Danton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/compaction.h | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'include/linux/compaction.h') diff --git a/include/linux/compaction.h b/include/linux/compaction.h index 7a9323aef4a3..51a90b7f2d60 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; } -- cgit v1.2.3