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

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Message-ID: <xa1tr3php7dk.fsf@mina86.com>
Date:	Fri, 12 Jun 2015 12:07:35 +0200
From:	Michal Nazarewicz <mina86@...a86.com>
To:	Vlastimil Babka <vbabka@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org
Cc:	linux-kernel@...r.kernel.org, Vlastimil Babka <vbabka@...e.cz>,
	Minchan Kim <minchan@...nel.org>, Mel Gorman <mgorman@...e.de>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Christoph Lameter <cl@...ux.com>,
	Rik van Riel <riel@...hat.com>,
	David Rientjes <rientjes@...gle.com>
Subject: Re: [PATCH 3/6] mm, compaction: encapsulate resetting cached scanner positions

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@...e.cz>
> Cc: Minchan Kim <minchan@...nel.org>
> Cc: Mel Gorman <mgorman@...e.de>
> Cc: Joonsoo Kim <iamjoonsoo.kim@....com>
> Cc: Michal Nazarewicz <mina86@...a86.com>

Acked-by: Michal Nazarewicz <mina86@...a86.com>

> Cc: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
> Cc: Christoph Lameter <cl@...ux.com>
> Cc: Rik van Riel <riel@...hat.com>
> Cc: David Rientjes <rientjes@...gle.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
>

-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michał “mina86” Nazarewicz    (o o)
ooo +--<mpn@...gle.com>--<xmpp:mina86@...ber.org>--ooO--(_)--Ooo--
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