On Mon, Sep 10, 2012 at 09:18:30AM +0800, Shaohua Li wrote:
> 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.
>
As I read old thread, you have the scenario and number.
Please include them in this description.
> 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>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
Other than some nitpicks, looks good to me.
> ---
> 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 */
I would like to add more specific condition.
/* True if a lock was contended in case of async compaction */
> };
>
> unsigned long
>
> --
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--
Kind regards,
Minchan Kim
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