Commit dc83edd9 authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
Browse files

mm: kswapd: use the classzone idx that kswapd was using for sleeping_prematurely() 



When kswapd is woken up for a high-order allocation, it takes account of
the highest usable zone by the caller (the classzone idx).  During
allocation, this index is used to select the lowmem_reserve[] that should
be applied to the watermark calculation in zone_watermark_ok().

When balancing a node, kswapd considers the highest unbalanced zone to be
the classzone index.  This will always be at least be the callers
classzone_idx and can be higher.  However, sleeping_prematurely() always
considers the lowest zone (e.g.  ZONE_DMA) to be the classzone index.
This means that sleeping_prematurely() can consider a zone to be balanced
that is unusable by the allocation request that originally woke kswapd.
This patch changes sleeping_prematurely() to use a classzone_idx matching
the value it used in balance_pgdat().

Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
Reviewed-by: default avatarEric B Munson <emunson@mgebm.net>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Simon Kirby <sim@hostway.ca>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
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 355b09c4

mm/vmscan.c

+16 −13
Original line number Diff line number Diff line
@@ -2227,7 +2227,8 @@ static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages, 
}



/* is kswapd sleeping prematurely? */

static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining)

static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining,

					int classzone_idx)

{

	int i;

	unsigned long balanced = 0;
@@ -2235,7 +2236,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) 


	/* If a direct reclaimer woke kswapd within HZ/10, it's premature */

	if (remaining)

		return 1;

		return true;



	/* Check the watermark levels */

	for (i = 0; i < pgdat->nr_zones; i++) {
@@ -2256,7 +2257,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) 
		}



		if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone),

								0, 0))

							classzone_idx, 0))

			all_zones_ok = false;

		else

			balanced += zone->present_pages;
@@ -2268,7 +2269,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) 
	 * must be balanced

	 */

	if (order)

		return pgdat_balanced(pgdat, balanced, 0);

		return pgdat_balanced(pgdat, balanced, classzone_idx);

	else

		return !all_zones_ok;

}
@@ -2295,7 +2296,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) 
 * of pages is balanced across the zones.

 */

static unsigned long balance_pgdat(pg_data_t *pgdat, int order,

							int classzone_idx)

							int *classzone_idx)

{

	int all_zones_ok;

	unsigned long balanced;
@@ -2358,6 +2359,7 @@ loop_again: 
			if (!zone_watermark_ok_safe(zone, order,

					high_wmark_pages(zone), 0, 0)) {

				end_zone = i;

				*classzone_idx = i;

				break;

			}

		}
@@ -2451,12 +2453,12 @@ loop_again: 
				 * spectulatively avoid congestion waits

				 */

				zone_clear_flag(zone, ZONE_CONGESTED);

				if (i <= classzone_idx)

				if (i <= *classzone_idx)

					balanced += zone->present_pages;

			}



		}

		if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, classzone_idx)))

		if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))

			break;		/* kswapd: all done */

		/*

		 * OK, kswapd is getting into trouble.  Take a nap, then take
@@ -2485,7 +2487,7 @@ out: 
	 * high-order: Balanced zones must make up at least 25% of the node

	 *             for the node to be balanced

	 */

	if (!(all_zones_ok || (order && pgdat_balanced(pgdat, balanced, classzone_idx)))) {

	if (!(all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))) {

		cond_resched();



		try_to_freeze();
@@ -2546,10 +2548,11 @@ out: 
	 * if another caller entered the allocator slow path while kswapd

	 * was awake, order will remain at the higher level

	 */

	*classzone_idx = end_zone;

	return order;

}



static void kswapd_try_to_sleep(pg_data_t *pgdat, int order)

static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx)

{

	long remaining = 0;

	DEFINE_WAIT(wait);
@@ -2560,7 +2563,7 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int order) 
	prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);



	/* Try to sleep for a short interval */

	if (!sleeping_prematurely(pgdat, order, remaining)) {

	if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) {

		remaining = schedule_timeout(HZ/10);

		finish_wait(&pgdat->kswapd_wait, &wait);

		prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
@@ -2570,7 +2573,7 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int order) 
	 * After a short sleep, check if it was a premature sleep. If not, then

	 * go fully to sleep until explicitly woken up.

	 */

	if (!sleeping_prematurely(pgdat, order, remaining)) {

	if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) {

		trace_mm_vmscan_kswapd_sleep(pgdat->node_id);



		/*
@@ -2658,7 +2661,7 @@ static int kswapd(void *p) 
			order = new_order;

			classzone_idx = new_classzone_idx;

		} else {

			kswapd_try_to_sleep(pgdat, order);

			kswapd_try_to_sleep(pgdat, order, classzone_idx);

			order = pgdat->kswapd_max_order;

			classzone_idx = pgdat->classzone_idx;

			pgdat->kswapd_max_order = 0;
@@ -2675,7 +2678,7 @@ static int kswapd(void *p) 
		 */

		if (!ret) {

			trace_mm_vmscan_kswapd_wake(pgdat->node_id, order);

			order = balance_pgdat(pgdat, order, classzone_idx);

			order = balance_pgdat(pgdat, order, &classzone_idx);

		}

	}

	return 0;

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