On Wed, Sep 12, 2012 at 05:46:15PM +0100, Richard Davies wrote:
> Hi Mel - thanks for replying to my underhand bcc!
>
> Mel Gorman wrote:
> > I see that this is an old-ish bug but I did not read the full history.
> > Is it now booting faster than 3.5.0 was? I'm asking because I'm
> > interested to see if commit c67fe375 helped your particular case.
>
> Yes, I think 3.6.0-rc5 is already better than 3.5.x but can still be
> improved, as discussed.
>
What are the boot times for each kernel?
> <PATCH SNIPPED>
>
> I have applied and tested again - perf results below.
>
> isolate_migratepages_range is indeed much reduced.
>
> There is now a lot of time in isolate_freepages_block and still quite a lot
> of lock contention, although in a different place.
>
This on top please.
---8<---
From: Shaohua Li <shli@xxxxxxxxxxxx>
compaction: abort compaction loop if lock is contended or run too long
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.
[minchan@xxxxxxxxxx: Putback pages isolated for migration if aborting]
[akpm@xxxxxxxxxxxxxxxxxxxx: Fixup one contended usage site]
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Shaohua Li <shli@xxxxxxxxxxxx>
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
---
mm/compaction.c | 17 ++++++++++++-----
mm/internal.h | 2 +-
2 files changed, 13 insertions(+), 6 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c
index 7fcd3a5..a8de20d 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;
}
@@ -634,7 +633,7 @@ 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;
@@ -787,6 +786,8 @@ 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;
@@ -831,6 +832,7 @@ static unsigned long compact_zone_order(struct zone *zone,
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 +840,17 @@ static unsigned long compact_zone_order(struct zone *zone,
.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);
+
+ 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 b8c91b3..4bd7c0e 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -130,7 +130,7 @@ 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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