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Commit 258401a6 authored by Zlatko Calusic's avatar Zlatko Calusic Committed by Linus Torvalds
Browse files

mm: don't wait on congested zones in balance_pgdat() 



From: Zlatko Calusic <zlatko.calusic@iskon.hr>

Commit 92df3a72 ("mm: vmscan: throttle reclaim if encountering too
many dirty pages under writeback") introduced waiting on congested zones
based on a sane algorithm in shrink_inactive_list().

What this means is that there's no more need for throttling and
additional heuristics in balance_pgdat().  So, let's remove it and tidy
up the code.

Signed-off-by: default avatarZlatko Calusic <zlatko.calusic@iskon.hr>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Johannes Weiner <jweiner@redhat.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 4db0e950

include/linux/vm_event_item.h

+0 −1
Original line number Original line Diff line number Diff line
@@ -36,7 +36,6 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, 
#endif

#endif

		PGINODESTEAL, SLABS_SCANNED, KSWAPD_INODESTEAL,

		PGINODESTEAL, SLABS_SCANNED, KSWAPD_INODESTEAL,

		KSWAPD_LOW_WMARK_HIT_QUICKLY, KSWAPD_HIGH_WMARK_HIT_QUICKLY,

		KSWAPD_LOW_WMARK_HIT_QUICKLY, KSWAPD_HIGH_WMARK_HIT_QUICKLY,

		KSWAPD_SKIP_CONGESTION_WAIT,

		PAGEOUTRUN, ALLOCSTALL, PGROTATED,

		PAGEOUTRUN, ALLOCSTALL, PGROTATED,

#ifdef CONFIG_NUMA_BALANCING

#ifdef CONFIG_NUMA_BALANCING

		NUMA_PTE_UPDATES,

		NUMA_PTE_UPDATES,

mm/vmscan.c

+1 −28
Original line number Original line Diff line number Diff line
@@ -2617,7 +2617,6 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, 
							int *classzone_idx)

							int *classzone_idx)

{

{

	bool pgdat_is_balanced = false;

	bool pgdat_is_balanced = false;

	struct zone *unbalanced_zone;

	int i;

	int i;

	int end_zone = 0;	/* Inclusive.  0 = ZONE_DMA */

	int end_zone = 0;	/* Inclusive.  0 = ZONE_DMA */

	unsigned long total_scanned;

	unsigned long total_scanned;
@@ -2648,9 +2647,6 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, 




	do {

	do {

		unsigned long lru_pages = 0;

		unsigned long lru_pages = 0;

		int has_under_min_watermark_zone = 0;



		unbalanced_zone = NULL;





		/*

		/*

		 * Scan in the highmem->dma direction for the highest

		 * Scan in the highmem->dma direction for the highest
@@ -2790,17 +2786,7 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, 
				continue;

				continue;

			}

			}





			if (!zone_balanced(zone, testorder, 0, end_zone)) {

			if (zone_balanced(zone, testorder, 0, end_zone))

				unbalanced_zone = zone;

				/*

				 * We are still under min water mark.  This

				 * means that we have a GFP_ATOMIC allocation

				 * failure risk. Hurry up!

				 */

				if (!zone_watermark_ok_safe(zone, order,

					    min_wmark_pages(zone), end_zone, 0))

					has_under_min_watermark_zone = 1;

			} else {

				/*

				/*

				 * If a zone reaches its high watermark,

				 * If a zone reaches its high watermark,

				 * consider it to be no longer congested. It's

				 * consider it to be no longer congested. It's
@@ -2811,8 +2797,6 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, 
				zone_clear_flag(zone, ZONE_CONGESTED);

				zone_clear_flag(zone, ZONE_CONGESTED);

		}

		}





		}



		/*

		/*

		 * If the low watermark is met there is no need for processes

		 * If the low watermark is met there is no need for processes

		 * to be throttled on pfmemalloc_wait as they should not be

		 * to be throttled on pfmemalloc_wait as they should not be
@@ -2827,17 +2811,6 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, 
			break;		/* kswapd: all done */

			break;		/* kswapd: all done */

		}

		}





		/*

		 * OK, kswapd is getting into trouble.  Take a nap, then take

		 * another pass across the zones.

		 */

		if (total_scanned && (sc.priority < DEF_PRIORITY - 2)) {

			if (has_under_min_watermark_zone)

				count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT);

			else if (unbalanced_zone)

				wait_iff_congested(unbalanced_zone, BLK_RW_ASYNC, HZ/10);

		}



		/*

		/*

		 * We do this so kswapd doesn't build up large priorities for

		 * We do this so kswapd doesn't build up large priorities for

		 * example when it is freeing in parallel with allocators. It

		 * example when it is freeing in parallel with allocators. It

mm/vmstat.c

+0 −1
Original line number Original line Diff line number Diff line
@@ -770,7 +770,6 @@ const char * const vmstat_text[] = { 
	"kswapd_inodesteal",

	"kswapd_inodesteal",

	"kswapd_low_wmark_hit_quickly",

	"kswapd_low_wmark_hit_quickly",

	"kswapd_high_wmark_hit_quickly",

	"kswapd_high_wmark_hit_quickly",

	"kswapd_skip_congestion_wait",

	"pageoutrun",

	"pageoutrun",

	"allocstall",

	"allocstall",