Commit 1cfb419b authored by KAMEZAWA Hiroyuki's avatar KAMEZAWA Hiroyuki Committed by Linus Torvalds
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per-zone and reclaim enhancements for memory controller: modifies vmscan.c for... 


per-zone and reclaim enhancements for memory controller: modifies vmscan.c for isolate globa/cgroup lru activity

When using memory controller, there are 2 levels of memory reclaim.
 1. zone memory reclaim because of system/zone memory shortage.
 2. memory cgroup memory reclaim because of hitting limit.

These two can be distinguished by sc->mem_cgroup parameter.
(scan_global_lru() macro)

This patch tries to make memory cgroup reclaim routine avoid affecting
system/zone memory reclaim. This patch inserts if (scan_global_lru()) and
hook to memory_cgroup reclaim support functions.

This patch can be a help for isolating system lru activity and group lru
activity and shows what additional functions are necessary.

 * mem_cgroup_calc_mapped_ratio() ... calculate mapped ratio for cgroup.
 * mem_cgroup_reclaim_imbalance() ... calculate active/inactive balance in
                                        cgroup.
 * mem_cgroup_calc_reclaim_active() ... calculate the number of active pages to
                                be scanned in this priority in mem_cgroup.

 * mem_cgroup_calc_reclaim_inactive() ... calculate the number of inactive pages
                                to be scanned in this priority in mem_cgroup.

 * mem_cgroup_all_unreclaimable() .. checks cgroup's page is all unreclaimable
                                     or not.
 * mem_cgroup_get_reclaim_priority() ...
 * mem_cgroup_note_reclaim_priority() ... record reclaim priority (temporal)
 * mem_cgroup_remember_reclaim_priority()
                             .... record reclaim priority as
                                  zone->prev_priority.
                                  This value is used for calc reclaim_mapped.

[akpm@linux-foundation.org: fix unused var warning]
Signed-off-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Paul Menage <menage@google.com>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent cc38108e

mm/vmscan.c

+201 −131
Original line number Diff line number Diff line
@@ -856,6 +856,7 @@ static unsigned long shrink_inactive_list(unsigned long max_scan, 
		__mod_zone_page_state(zone, NR_ACTIVE, -nr_active);

		__mod_zone_page_state(zone, NR_INACTIVE,

						-(nr_taken - nr_active));

		if (scan_global_lru(sc))

			zone->pages_scanned += nr_scan;

		spin_unlock_irq(&zone->lru_lock);
@@ -888,8 +889,9 @@ static unsigned long shrink_inactive_list(unsigned long max_scan, 
		if (current_is_kswapd()) {

			__count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scan);

			__count_vm_events(KSWAPD_STEAL, nr_freed);

		} else

		} else if (scan_global_lru(sc))

			__count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scan);



		__count_zone_vm_events(PGSTEAL, zone, nr_freed);



		if (nr_taken == 0)
@@ -943,49 +945,31 @@ static inline int zone_is_near_oom(struct zone *zone) 
}



/*

 * This moves pages from the active list to the inactive list.

 *

 * We move them the other way if the page is referenced by one or more

 * processes, from rmap.

 *

 * If the pages are mostly unmapped, the processing is fast and it is

 * appropriate to hold zone->lru_lock across the whole operation.  But if

 * the pages are mapped, the processing is slow (page_referenced()) so we

 * should drop zone->lru_lock around each page.  It's impossible to balance

 * this, so instead we remove the pages from the LRU while processing them.

 * It is safe to rely on PG_active against the non-LRU pages in here because

 * nobody will play with that bit on a non-LRU page.

 *

 * The downside is that we have to touch page->_count against each page.

 * But we had to alter page->flags anyway.

 * Determine we should try to reclaim mapped pages.

 * This is called only when sc->mem_cgroup is NULL.

 */

static void shrink_active_list(unsigned long nr_pages, struct zone *zone,

				struct scan_control *sc, int priority)

static int calc_reclaim_mapped(struct scan_control *sc, struct zone *zone,

				int priority)

{

	unsigned long pgmoved;

	int pgdeactivate = 0;

	unsigned long pgscanned;

	LIST_HEAD(l_hold);	/* The pages which were snipped off */

	LIST_HEAD(l_inactive);	/* Pages to go onto the inactive_list */

	LIST_HEAD(l_active);	/* Pages to go onto the active_list */

	struct page *page;

	struct pagevec pvec;

	int reclaim_mapped = 0;



	if (sc->may_swap) {

	long mapped_ratio;

	long distress;

	long swap_tendency;

	long imbalance;

	int reclaim_mapped = 0;

	int prev_priority;



		if (zone_is_near_oom(zone))

			goto force_reclaim_mapped;



	if (scan_global_lru(sc) && zone_is_near_oom(zone))

		return 1;

	/*

	 * `distress' is a measure of how much trouble we're having

	 * reclaiming pages.  0 -> no problems.  100 -> great trouble.

	 */

		distress = 100 >> min(zone->prev_priority, priority);

	if (scan_global_lru(sc))

		prev_priority = zone->prev_priority;

	else

		prev_priority = mem_cgroup_get_reclaim_priority(sc->mem_cgroup);



	distress = 100 >> min(prev_priority, priority);



	/*

	 * The point of this algorithm is to decide when to start
@@ -993,9 +977,12 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone, 
	 * how much memory

	 * is mapped.

	 */

	if (scan_global_lru(sc))

		mapped_ratio = ((global_page_state(NR_FILE_MAPPED) +

				global_page_state(NR_ANON_PAGES)) * 100) /

					vm_total_pages;

	else

		mapped_ratio = mem_cgroup_calc_mapped_ratio(sc->mem_cgroup);



	/*

	 * Now decide how much we really want to unmap some pages.  The
@@ -1023,8 +1010,11 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone, 
	 * Avoid div by zero with nr_inactive+1, and max resulting

	 * value is vm_total_pages.

	 */

	if (scan_global_lru(sc)) {

		imbalance  = zone_page_state(zone, NR_ACTIVE);

		imbalance /= zone_page_state(zone, NR_INACTIVE) + 1;

	} else

		imbalance = mem_cgroup_reclaim_imbalance(sc->mem_cgroup);



	/*

	 * Reduce the effect of imbalance if swappiness is low,
@@ -1056,16 +1046,58 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone, 
	 * memory onto the inactive list.

	 */

	if (swap_tendency >= 100)

force_reclaim_mapped:

		reclaim_mapped = 1;



	return reclaim_mapped;

}



/*

 * This moves pages from the active list to the inactive list.

 *

 * We move them the other way if the page is referenced by one or more

 * processes, from rmap.

 *

 * If the pages are mostly unmapped, the processing is fast and it is

 * appropriate to hold zone->lru_lock across the whole operation.  But if

 * the pages are mapped, the processing is slow (page_referenced()) so we

 * should drop zone->lru_lock around each page.  It's impossible to balance

 * this, so instead we remove the pages from the LRU while processing them.

 * It is safe to rely on PG_active against the non-LRU pages in here because

 * nobody will play with that bit on a non-LRU page.

 *

 * The downside is that we have to touch page->_count against each page.

 * But we had to alter page->flags anyway.

 */





static void shrink_active_list(unsigned long nr_pages, struct zone *zone,

				struct scan_control *sc, int priority)

{

	unsigned long pgmoved;

	int pgdeactivate = 0;

	unsigned long pgscanned;

	LIST_HEAD(l_hold);	/* The pages which were snipped off */

	LIST_HEAD(l_inactive);	/* Pages to go onto the inactive_list */

	LIST_HEAD(l_active);	/* Pages to go onto the active_list */

	struct page *page;

	struct pagevec pvec;

	int reclaim_mapped = 0;



	if (sc->may_swap)

		reclaim_mapped = calc_reclaim_mapped(sc, zone, priority);



	lru_add_drain();

	spin_lock_irq(&zone->lru_lock);

	pgmoved = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order,

					ISOLATE_ACTIVE, zone,

					sc->mem_cgroup, 1);

	/*

	 * zone->pages_scanned is used for detect zone's oom

	 * mem_cgroup remembers nr_scan by itself.

	 */

	if (scan_global_lru(sc))

		zone->pages_scanned += pgscanned;



	__mod_zone_page_state(zone, NR_ACTIVE, -pgmoved);

	spin_unlock_irq(&zone->lru_lock);
@@ -1155,18 +1187,14 @@ static unsigned long shrink_zone(int priority, struct zone *zone, 
	unsigned long nr_to_scan;

	unsigned long nr_reclaimed = 0;



	if (scan_global_lru(sc)) {

		/*

	 * Add one to `nr_to_scan' just to make sure that the kernel will

	 * slowly sift through the active list.

		 * Add one to nr_to_scan just to make sure that the kernel

		 * will slowly sift through the active list.

		 */

		zone->nr_scan_active +=

			(zone_page_state(zone, NR_ACTIVE) >> priority) + 1;

		nr_active = zone->nr_scan_active;

	if (nr_active >= sc->swap_cluster_max)

		zone->nr_scan_active = 0;

	else

		nr_active = 0;



		zone->nr_scan_inactive +=

			(zone_page_state(zone, NR_INACTIVE) >> priority) + 1;

		nr_inactive = zone->nr_scan_inactive;
@@ -1175,6 +1203,24 @@ static unsigned long shrink_zone(int priority, struct zone *zone, 
		else

			nr_inactive = 0;



		if (nr_active >= sc->swap_cluster_max)

			zone->nr_scan_active = 0;

		else

			nr_active = 0;

	} else {

		/*

		 * This reclaim occurs not because zone memory shortage but

		 * because memory controller hits its limit.

		 * Then, don't modify zone reclaim related data.

		 */

		nr_active = mem_cgroup_calc_reclaim_active(sc->mem_cgroup,

					zone, priority);



		nr_inactive = mem_cgroup_calc_reclaim_inactive(sc->mem_cgroup,

					zone, priority);

	}





	while (nr_active || nr_inactive) {

		if (nr_active) {

			nr_to_scan = min(nr_active,
@@ -1218,25 +1264,39 @@ static unsigned long shrink_zones(int priority, struct zone **zones, 
	unsigned long nr_reclaimed = 0;

	int i;





	sc->all_unreclaimable = 1;

	for (i = 0; zones[i] != NULL; i++) {

		struct zone *zone = zones[i];



		if (!populated_zone(zone))

			continue;



		/*

		 * Take care memory controller reclaiming has small influence

		 * to global LRU.

		 */

		if (scan_global_lru(sc)) {

			if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))

				continue;



			note_zone_scanning_priority(zone, priority);



		if (zone_is_all_unreclaimable(zone) && priority != DEF_PRIORITY)

			if (zone_is_all_unreclaimable(zone) &&

						priority != DEF_PRIORITY)

				continue;	/* Let kswapd poll it */



			sc->all_unreclaimable = 0;

		} else {

			/*

			 * Ignore cpuset limitation here. We just want to reduce

			 * # of used pages by us regardless of memory shortage.

			 */

			sc->all_unreclaimable = 0;

			mem_cgroup_note_reclaim_priority(sc->mem_cgroup,

							priority);

		}



		nr_reclaimed += shrink_zone(priority, zone, sc);

	}



	return nr_reclaimed;

}
@@ -1264,8 +1324,12 @@ static unsigned long do_try_to_free_pages(struct zone **zones, gfp_t gfp_mask, 
	unsigned long lru_pages = 0;

	int i;



	if (scan_global_lru(sc))

		count_vm_event(ALLOCSTALL);



	/*

	 * mem_cgroup will not do shrink_slab.

	 */

	if (scan_global_lru(sc)) {

		for (i = 0; zones[i] != NULL; i++) {

			struct zone *zone = zones[i];
@@ -1275,6 +1339,7 @@ static unsigned long do_try_to_free_pages(struct zone **zones, gfp_t gfp_mask, 
			lru_pages += zone_page_state(zone, NR_ACTIVE)

					+ zone_page_state(zone, NR_INACTIVE);

		}

	}



	for (priority = DEF_PRIORITY; priority >= 0; priority--) {

		sc->nr_scanned = 0;
@@ -1330,6 +1395,8 @@ out: 
	 */

	if (priority < 0)

		priority = 0;



	if (scan_global_lru(sc)) {

		for (i = 0; zones[i] != NULL; i++) {

			struct zone *zone = zones[i];
@@ -1338,6 +1405,9 @@ out: 


			zone->prev_priority = priority;

		}

	} else

		mem_cgroup_record_reclaim_priority(sc->mem_cgroup, priority);



	return ret;

}

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