Patchwork [4/9] mm: compaction: Abort compaction loop if lock is contended or run too long

login
register
mail settings
Submitter Mel Gorman
Date Sept. 21, 2012, 10:46 a.m.
Message ID <1348224383-1499-5-git-send-email-mgorman@suse.de>
Download mbox | patch
Permalink /patch/185723/
State New
Headers show

Comments

Mel Gorman - Sept. 21, 2012, 10:46 a.m.
From: Shaohua Li <shli@fusionio.com>

Changelog since V2
o Fix BUG_ON triggered due to pages left on cc.migratepages
o Make compact_zone_order() require non-NULL arg `contended'

Changelog since V1
o only abort the compaction if lock is contended or run too long
o Rearranged the code by Andrea Arcangeli.

isolate_migratepages_range() might isolate no pages if for example when
zone->lru_lock is contended and running asynchronous compaction. In this
case, we should abort compaction, otherwise, compact_zone will run a
useless loop and make zone->lru_lock is even contended.

[minchan@kernel.org: Putback pages isolated for migration if aborting]
[akpm@linux-foundation.org: compact_zone_order requires non-NULL arg contended]
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
---
 mm/compaction.c |   17 ++++++++++++-----
 mm/internal.h   |    2 +-
 2 files changed, 13 insertions(+), 6 deletions(-)
Rafael Aquini - Sept. 21, 2012, 5:50 p.m.
On Fri, Sep 21, 2012 at 11:46:18AM +0100, Mel Gorman wrote:
> From: Shaohua Li <shli@fusionio.com>
> 
> Changelog since V2
> o Fix BUG_ON triggered due to pages left on cc.migratepages
> o Make compact_zone_order() require non-NULL arg `contended'
> 
> Changelog since V1
> o only abort the compaction if lock is contended or run too long
> o Rearranged the code by Andrea Arcangeli.
> 
> isolate_migratepages_range() might isolate no pages if for example when
> zone->lru_lock is contended and running asynchronous compaction. In this
> case, we should abort compaction, otherwise, compact_zone will run a
> useless loop and make zone->lru_lock is even contended.
> 
> [minchan@kernel.org: Putback pages isolated for migration if aborting]
> [akpm@linux-foundation.org: compact_zone_order requires non-NULL arg contended]
> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
> Signed-off-by: Shaohua Li <shli@fusionio.com>
> Signed-off-by: Mel Gorman <mgorman@suse.de>
> Acked-by: Rik van Riel <riel@redhat.com>
> ---

Acked-by: Rafael Aquini <aquini@redhat.com>
Andrew Morton - Sept. 21, 2012, 9:31 p.m.
On Fri, 21 Sep 2012 11:46:18 +0100
Mel Gorman <mgorman@suse.de> wrote:

> Changelog since V2
> o Fix BUG_ON triggered due to pages left on cc.migratepages
> o Make compact_zone_order() require non-NULL arg `contended'
> 
> Changelog since V1
> o only abort the compaction if lock is contended or run too long
> o Rearranged the code by Andrea Arcangeli.
> 
> isolate_migratepages_range() might isolate no pages if for example when
> zone->lru_lock is contended and running asynchronous compaction. In this
> case, we should abort compaction, otherwise, compact_zone will run a
> useless loop and make zone->lru_lock is even contended.

hm, this appears to be identical to

mm-compaction-abort-compaction-loop-if-lock-is-contended-or-run-too-long.patch
mm-compaction-abort-compaction-loop-if-lock-is-contended-or-run-too-long-fix.patch
mm-compaction-abort-compaction-loop-if-lock-is-contended-or-run-too-long-fix-2.patch

so I simply omitted patches 2, 3 and 4.
Minchan Kim - Sept. 25, 2012, 7:34 a.m.
On Fri, Sep 21, 2012 at 11:46:18AM +0100, Mel Gorman wrote:
> From: Shaohua Li <shli@fusionio.com>
> 
> Changelog since V2
> o Fix BUG_ON triggered due to pages left on cc.migratepages
> o Make compact_zone_order() require non-NULL arg `contended'
> 
> Changelog since V1
> o only abort the compaction if lock is contended or run too long
> o Rearranged the code by Andrea Arcangeli.
> 
> isolate_migratepages_range() might isolate no pages if for example when
> zone->lru_lock is contended and running asynchronous compaction. In this
> case, we should abort compaction, otherwise, compact_zone will run a
> useless loop and make zone->lru_lock is even contended.
> 
> [minchan@kernel.org: Putback pages isolated for migration if aborting]
> [akpm@linux-foundation.org: compact_zone_order requires non-NULL arg contended]
> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
> Signed-off-by: Shaohua Li <shli@fusionio.com>
> Signed-off-by: Mel Gorman <mgorman@suse.de>
> Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Minchan Kim <minchan@kernel.org>

Patch

diff --git a/mm/compaction.c b/mm/compaction.c
index 614f18b..6b55491 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -70,8 +70,7 @@  static bool compact_checklock_irqsave(spinlock_t *lock, unsigned long *flags,
 
 		/* async aborts if taking too long or contended */
 		if (!cc->sync) {
-			if (cc->contended)
-				*cc->contended = true;
+			cc->contended = true;
 			return false;
 		}
 
@@ -686,7 +685,7 @@  static isolate_migrate_t isolate_migratepages(struct zone *zone,
 
 	/* Perform the isolation */
 	low_pfn = isolate_migratepages_range(zone, cc, low_pfn, end_pfn);
-	if (!low_pfn)
+	if (!low_pfn || cc->contended)
 		return ISOLATE_ABORT;
 
 	cc->migrate_pfn = low_pfn;
@@ -846,6 +845,8 @@  static int compact_zone(struct zone *zone, struct compact_control *cc)
 		switch (isolate_migratepages(zone, cc)) {
 		case ISOLATE_ABORT:
 			ret = COMPACT_PARTIAL;
+			putback_lru_pages(&cc->migratepages);
+			cc->nr_migratepages = 0;
 			goto out;
 		case ISOLATE_NONE:
 			continue;
@@ -894,6 +895,7 @@  static unsigned long compact_zone_order(struct zone *zone,
 				 bool sync, bool *contended,
 				 struct page **page)
 {
+	unsigned long ret;
 	struct compact_control cc = {
 		.nr_freepages = 0,
 		.nr_migratepages = 0,
@@ -901,13 +903,18 @@  static unsigned long compact_zone_order(struct zone *zone,
 		.migratetype = allocflags_to_migratetype(gfp_mask),
 		.zone = zone,
 		.sync = sync,
-		.contended = contended,
 		.page = page,
 	};
 	INIT_LIST_HEAD(&cc.freepages);
 	INIT_LIST_HEAD(&cc.migratepages);
 
-	return compact_zone(zone, &cc);
+	ret = compact_zone(zone, &cc);
+
+	VM_BUG_ON(!list_empty(&cc.freepages));
+	VM_BUG_ON(!list_empty(&cc.migratepages));
+
+	*contended = cc.contended;
+	return ret;
 }
 
 int sysctl_extfrag_threshold = 500;
diff --git a/mm/internal.h b/mm/internal.h
index 386772f..eebbed5 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -131,7 +131,7 @@  struct compact_control {
 	int order;			/* order a direct compactor needs */
 	int migratetype;		/* MOVABLE, RECLAIMABLE etc */
 	struct zone *zone;
-	bool *contended;		/* True if a lock was contended */
+	bool contended;			/* True if a lock was contended */
 	struct page **page;		/* Page captured of requested size */
 };