Re: [PATCH v2] mm: remove MIGRATE_ISOLATE check in hotpath

[Michal Nazarewicz <mina86@mina86.com>]

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On Tue, Jan 15 2013, Minchan Kim wrote:
> Now mm several functions test MIGRATE_ISOLATE and some of those
> are hotpath but MIGRATE_ISOLATE is used only if we enable
> CONFIG_MEMORY_ISOLATION(ie, CMA, memory-hotplug and memory-failure)
> which are not common config option. So let's not add unnecessary
> overhead and code when we don't enable CONFIG_MEMORY_ISOLATION.
>
> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> Cc: Michal Nazarewicz <mina86@mina86.com>

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

> Signed-off-by: Minchan Kim <minchan@kernel.org>
> ---
>  include/linux/mmzone.h         |    2 ++
>  include/linux/page-isolation.h |   19 +++++++++++++++++++
>  mm/compaction.c                |    6 +++++-
>  mm/page_alloc.c                |   16 ++++++++++------
>  mm/vmstat.c                    |    2 ++
>  5 files changed, 38 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 73b64a3..4f4c8c2 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -57,7 +57,9 @@ enum {
>  	 */
>  	MIGRATE_CMA,
>  #endif
> +#ifdef CONFIG_MEMORY_ISOLATION
>  	MIGRATE_ISOLATE,	/* can't allocate from here */
> +#endif
>  	MIGRATE_TYPES
>  };
>  
> diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h
> index a92061e..3fff8e7 100644
> --- a/include/linux/page-isolation.h
> +++ b/include/linux/page-isolation.h
> @@ -1,6 +1,25 @@
>  #ifndef __LINUX_PAGEISOLATION_H
>  #define __LINUX_PAGEISOLATION_H
>  
> +#ifdef CONFIG_MEMORY_ISOLATION
> +static inline bool is_migrate_isolate_page(struct page *page)
> +{
> +	return get_pageblock_migratetype(page) == MIGRATE_ISOLATE;
> +}
> +static inline bool is_migrate_isolate(int migratetype)
> +{
> +	return migratetype == MIGRATE_ISOLATE;
> +}
> +#else
> +static inline bool is_migrate_isolate_page(struct page *page)
> +{
> +	return false;
> +}
> +static inline bool is_migrate_isolate(int migratetype)
> +{
> +	return false;
> +}
> +#endif
>  
>  bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
>  			 bool skip_hwpoisoned_pages);
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 675937c..bb2a655 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -15,6 +15,7 @@
>  #include <linux/sysctl.h>
>  #include <linux/sysfs.h>
>  #include <linux/balloon_compaction.h>
> +#include <linux/page-isolation.h>
>  #include "internal.h"
>  
>  #ifdef CONFIG_COMPACTION
> @@ -215,7 +216,10 @@ static bool suitable_migration_target(struct page *page)
>  	int migratetype = get_pageblock_migratetype(page);
>  
>  	/* Don't interfere with memory hot-remove or the min_free_kbytes blocks */
> -	if (migratetype == MIGRATE_ISOLATE || migratetype == MIGRATE_RESERVE)
> +	if (migratetype == MIGRATE_RESERVE)
> +		return false;
> +
> +	if (is_migrate_isolate(migratetype))
>  		return false;
>  
>  	/* If the page is a large free page, then allow migration */
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 82117f5..319a8f0 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -665,7 +665,7 @@ static void free_pcppages_bulk(struct zone *zone, int count,
>  			/* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */
>  			__free_one_page(page, zone, 0, mt);
>  			trace_mm_page_pcpu_drain(page, 0, mt);
> -			if (likely(get_pageblock_migratetype(page) != MIGRATE_ISOLATE)) {
> +			if (likely(!is_migrate_isolate_page(page))) {
>  				__mod_zone_page_state(zone, NR_FREE_PAGES, 1);
>  				if (is_migrate_cma(mt))
>  					__mod_zone_page_state(zone, NR_FREE_CMA_PAGES, 1);
> @@ -683,7 +683,7 @@ static void free_one_page(struct zone *zone, struct page *page, int order,
>  	zone->pages_scanned = 0;
>  
>  	__free_one_page(page, zone, order, migratetype);
> -	if (unlikely(migratetype != MIGRATE_ISOLATE))
> +	if (unlikely(!is_migrate_isolate(migratetype)))
>  		__mod_zone_freepage_state(zone, 1 << order, migratetype);
>  	spin_unlock(&zone->lock);
>  }
> @@ -911,7 +911,9 @@ static int fallbacks[MIGRATE_TYPES][4] = {
>  	[MIGRATE_MOVABLE]     = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE,   MIGRATE_RESERVE },
>  #endif
>  	[MIGRATE_RESERVE]     = { MIGRATE_RESERVE }, /* Never used */
> +#ifdef CONFIG_MEMORY_ISOLATION
>  	[MIGRATE_ISOLATE]     = { MIGRATE_RESERVE }, /* Never used */
> +#endif
>  };
>  
>  /*
> @@ -1137,7 +1139,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
>  			list_add_tail(&page->lru, list);
>  		if (IS_ENABLED(CONFIG_CMA)) {
>  			mt = get_pageblock_migratetype(page);
> -			if (!is_migrate_cma(mt) && mt != MIGRATE_ISOLATE)
> +			if (!is_migrate_cma(mt) && !is_migrate_isolate(mt))
>  				mt = migratetype;
>  		}
>  		set_freepage_migratetype(page, mt);
> @@ -1321,7 +1323,7 @@ void free_hot_cold_page(struct page *page, int cold)
>  	 * excessively into the page allocator
>  	 */
>  	if (migratetype >= MIGRATE_PCPTYPES) {
> -		if (unlikely(migratetype == MIGRATE_ISOLATE)) {
> +		if (unlikely(is_migrate_isolate(migratetype))) {
>  			free_one_page(zone, page, 0, migratetype);
>  			goto out;
>  		}
> @@ -1402,7 +1404,7 @@ int capture_free_page(struct page *page, int alloc_order, int migratetype)
>  	order = page_order(page);
>  	mt = get_pageblock_migratetype(page);
>  
> -	if (mt != MIGRATE_ISOLATE) {
> +	if (!is_migrate_isolate(mt)) {
>  		/* Obey watermarks as if the page was being allocated */
>  		watermark = low_wmark_pages(zone) + (1 << order);
>  		if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
> @@ -1425,7 +1427,7 @@ int capture_free_page(struct page *page, int alloc_order, int migratetype)
>  		struct page *endpage = page + (1 << order) - 1;
>  		for (; page < endpage; page += pageblock_nr_pages) {
>  			int mt = get_pageblock_migratetype(page);
> -			if (mt != MIGRATE_ISOLATE && !is_migrate_cma(mt))
> +			if (!is_migrate_isolate(mt) && !is_migrate_cma(mt))
>  				set_pageblock_migratetype(page,
>  							  MIGRATE_MOVABLE);
>  		}
> @@ -2911,7 +2913,9 @@ static void show_migration_types(unsigned char type)
>  #ifdef CONFIG_CMA
>  		[MIGRATE_CMA]		= 'C',
>  #endif
> +#ifdef CONFIG_MEMORY_ISOLATION
>  		[MIGRATE_ISOLATE]	= 'I',
> +#endif
>  	};
>  	char tmp[MIGRATE_TYPES + 1];
>  	char *p = tmp;
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 7a65e26..b0f1db1 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -628,7 +628,9 @@ static char * const migratetype_names[MIGRATE_TYPES] = {
>  #ifdef CONFIG_CMA
>  	"CMA",
>  #endif
> +#ifdef CONFIG_MEMORY_ISOLATION
>  	"Isolate",
> +#endif
>  };
>  
>  static void *frag_start(struct seq_file *m, loff_t *pos)

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

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