isolate_migratepages_range() might isolate none pages, for example, when
zone->lru_lock is contended and compaction is async. In this case, we should
abort compaction, otherwise, compact_zone will run a useless loop and make
zone->lru_lock is even contended.
V2:
only abort the compaction if lock is contended or run too long
Rearranged the code by Andrea Arcangeli.
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Shaohua Li <shli@xxxxxxxxxxxx>
---
mm/compaction.c | 12 +++++++-----
mm/internal.h | 2 +-
2 files changed, 8 insertions(+), 6 deletions(-)
Index: linux/mm/compaction.c
===================================================================
--- linux.orig/mm/compaction.c 2012-09-06 18:37:52.636413761 +0800
+++ linux/mm/compaction.c 2012-09-10 08:49:40.377869710 +0800
@@ -70,8 +70,7 @@ static bool compact_checklock_irqsave(sp
/* async aborts if taking too long or contended */
if (!cc->sync) {
- if (cc->contended)
- *cc->contended = true;
+ cc->contended = true;
return false;
}
@@ -634,7 +633,7 @@ static isolate_migrate_t isolate_migrate
/* 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;
@@ -831,6 +830,7 @@ static unsigned long compact_zone_order(
int order, gfp_t gfp_mask,
bool sync, bool *contended)
{
+ unsigned long ret;
struct compact_control cc = {
.nr_freepages = 0,
.nr_migratepages = 0,
@@ -838,12 +838,14 @@ static unsigned long compact_zone_order(
.migratetype = allocflags_to_migratetype(gfp_mask),
.zone = zone,
.sync = sync,
- .contended = contended,
};
INIT_LIST_HEAD(&cc.freepages);
INIT_LIST_HEAD(&cc.migratepages);
- return compact_zone(zone, &cc);
+ ret = compact_zone(zone, &cc);
+ if (contended)
+ *contended = cc.contended;
+ return ret;
}
int sysctl_extfrag_threshold = 500;
Index: linux/mm/internal.h
===================================================================
--- linux.orig/mm/internal.h 2012-09-03 15:16:30.566299444 +0800
+++ linux/mm/internal.h 2012-09-10 08:45:41.980866645 +0800
@@ -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 */
};
unsigned long
--
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