Re: [PATCH 3/6] mm, compaction: encapsulate resetting cached scanner positions

Michal Nazarewicz
2015-06-12T10:07:42Z

On Wed, Jun 10 2015, Vlastimil Babka wrote:
> Resetting the cached compaction scanner positions is now done implicitly in
> __reset_isolation_suitable() and compact_finished(). Encapsulate the
> functionality in a new function reset_cached_positions() and call it explicitly
> where needed.
>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Michal Nazarewicz <mina86@mina86.com>

Acked-by: Michal Nazarewicz <mina86@mina86.com>

> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Rik van Riel <riel@redhat.com>
> Cc: David Rientjes <rientjes@google.com>
> ---
> mm/compaction.c | 22 ++++++++++++++--------
> 1 file changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 7e0a814..d334bb3 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -207,6 +207,13 @@ static inline bool isolation_suitable(struct compact_control *cc,
> return !get_pageblock_skip(page);
> }
>
> +static void reset_cached_positions(struct zone *zone)
> +{
> + zone->compact_cached_migrate_pfn[0] = zone->zone_start_pfn;
> + zone->compact_cached_migrate_pfn[1] = zone->zone_start_pfn;
> + zone->compact_cached_free_pfn = zone_end_pfn(zone);
> +}
> +
> /*
> * This function is called to clear all cached information on pageblocks that
> * should be skipped for page isolation when the migrate and free page scanner
> @@ -218,9 +225,6 @@ static void __reset_isolation_suitable(struct zone *zone)
> unsigned long end_pfn = zone_end_pfn(zone);
> unsigned long pfn;
>
> - zone->compact_cached_migrate_pfn[0] = start_pfn;
> - zone->compact_cached_migrate_pfn[1] = start_pfn;
> - zone->compact_cached_free_pfn = end_pfn;
> zone->compact_blockskip_flush = false;
>
> /* Walk the zone and mark every pageblock as suitable for isolation */
> @@ -250,8 +254,10 @@ void reset_isolation_suitable(pg_data_t *pgdat)
> continue;
>
> /* Only flush if a full compaction finished recently */
> - if (zone->compact_blockskip_flush)
> + if (zone->compact_blockskip_flush) {
> __reset_isolation_suitable(zone);
> + reset_cached_positions(zone);
> + }
> }
> }
>
> @@ -1164,9 +1170,7 @@ static int __compact_finished(struct zone *zone, struct compact_control *cc,
> /* Compaction run completes if the migrate and free scanner meet */
> if (compact_scanners_met(cc)) {
> /* Let the next compaction start anew. */
> - zone->compact_cached_migrate_pfn[0] = zone->zone_start_pfn;
> - zone->compact_cached_migrate_pfn[1] = zone->zone_start_pfn;
> - zone->compact_cached_free_pfn = zone_end_pfn(zone);
> + reset_cached_positions(zone);
>
> /*
> * Mark that the PG_migrate_skip information should be cleared
> @@ -1329,8 +1333,10 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
> * is about to be retried after being deferred. kswapd does not do
> * this reset as it'll reset the cached information when going to sleep.
> */
> - if (compaction_restarting(zone, cc->order) && !current_is_kswapd())
> + if (compaction_restarting(zone, cc->order) && !current_is_kswapd()) {
> __reset_isolation_suitable(zone);
> + reset_cached_positions(zone);
> + }
>
> /*
> * Setup to move all movable pages to the end of the zone. Used cached
> --
> 2.1.4
>

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..o | Computer Science, Michał “mina86” Nazarewicz (o o)
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