vmscan: ZVC updates in shrink_active_list() can be done once

PATCH In review Wu Fengguang 4 participants 5 messages May 4, 2009 – May 5, 2009

Subsystems (3)

Memory management MGLRU MM reclaim

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Wu Fengguang

author

2009-05-04 23:44 UTC #0 lore raw

PATCH 1/1 vmscan: ZVC updates in shrink_active_list() can be done once

This effectively lifts the unit of nr_inactive_* and pgdeactivate updates from PAGEVEC_SIZE=14 to SWAP_CLUSTER_MAX=32.

Signed-off-by Wu Fengguang <[email protected]>

---
 mm/vmscan.c |   11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

mm/vmscan.c +3 -8

@@ -1228,7 +1228,6 @@ static void shrink_active_list(unsigned 
 			struct scan_control *sc, int priority, int file)
 {
 	unsigned long pgmoved;
-	int pgdeactivate = 0;
 	unsigned long pgscanned;
 	LIST_HEAD(l_hold);	/* The pages which were snipped off */
 	LIST_HEAD(l_inactive);

@@ -1257,7 +1256,7 @@ static void shrink_active_list(unsigned 
 		__mod_zone_page_state(zone, NR_ACTIVE_ANON, -pgmoved);
 	spin_unlock_irq(&zone->lru_lock);
 
-	pgmoved = 0;
+	pgmoved = 0;  /* count referenced (mapping) mapped pages */
 	while (!list_empty(&l_hold)) {
 		cond_resched();
 		page = lru_to_page(&l_hold);

@@ -1291,7 +1290,7 @@ static void shrink_active_list(unsigned 
 	 */
 	reclaim_stat->recent_rotated[!!file] += pgmoved;
 
-	pgmoved = 0;
+	pgmoved = 0;  /* count pages moved to inactive list */
 	while (!list_empty(&l_inactive)) {
 		page = lru_to_page(&l_inactive);
 		prefetchw_prev_lru_page(page, &l_inactive, flags);

@@ -1304,10 +1303,7 @@ static void shrink_active_list(unsigned 
 		mem_cgroup_add_lru_list(page, lru);
 		pgmoved++;
 		if (!pagevec_add(&pvec, page)) {
-			__mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
 			spin_unlock_irq(&zone->lru_lock);
-			pgdeactivate += pgmoved;
-			pgmoved = 0;
 			if (buffer_heads_over_limit)
 				pagevec_strip(&pvec);
 			__pagevec_release(&pvec);

@@ -1315,9 +1311,8 @@ static void shrink_active_list(unsigned 
 		}
 	}
 	__mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
-	pgdeactivate += pgmoved;
 	__count_zone_vm_events(PGREFILL, zone, pgscanned);
-	__count_vm_events(PGDEACTIVATE, pgdeactivate);
+	__count_vm_events(PGDEACTIVATE, pgmoved);
 	spin_unlock_irq(&zone->lru_lock);
 	if (buffer_heads_over_limit)
 		pagevec_strip(&pvec);

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Minchan Kim

Reviewed-by on v1 1/1

2009-05-05 02:45 UTC #1 lore raw

Reviewed-by Minchan Kim <[email protected]>

This fine-grained ZVC update in shrink_active_list was made for determination problem of the dirty ratio(c878538598d1e7ab41ecc0de8894e34e2fdef630).
The 32 page reclaim time in normal reclaim situation is too short to change current VM behavior.
So I think this make sense to me.

Quoted 65 lines · Wu Fengguang

This effectively lifts the unit of nr_inactive_* and pgdeactivate updates from PAGEVEC_SIZE=14 to SWAP_CLUSTER_MAX=32.

Signed-off-by Wu Fengguang <[email protected]>

---
mm/vmscan.c | 11 +++--------

 1 file changed, 3 insertions(+), 8 deletions(-)

mm/vmscan.c +0 -1

@@ -1228,7 +1228,6 @@ static void shrink_active_list(unsigned
                        struct scan_control *sc, int priority, int file)
  {
        unsigned long pgmoved;
-       int pgdeactivate = 0;
        unsigned long pgscanned;

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

mm/vmscan.c +3 -8

@@ -1257,7 +1256,7 @@ static void shrink_active_list(unsigned
                __mod_zone_page_state(zone, NR_ACTIVE_ANON, -pgmoved);
        spin_unlock_irq(&zone->lru_lock);
 
-       pgmoved = 0;
+       pgmoved = 0;  /* count referenced (mapping) mapped pages */
        while (!list_empty(&l_hold)) {
                cond_resched();
                page = lru_to_page(&l_hold);

@@ -1291,7 +1290,7 @@ static void shrink_active_list(unsigned
         */
        reclaim_stat->recent_rotated[!!file] += pgmoved;
 
-       pgmoved = 0;
+       pgmoved = 0;  /* count pages moved to inactive list */
        while (!list_empty(&l_inactive)) {
                page = lru_to_page(&l_inactive);
                prefetchw_prev_lru_page(page, &l_inactive, flags);

@@ -1304,10 +1303,7 @@ static void shrink_active_list(unsigned
                mem_cgroup_add_lru_list(page, lru);
                pgmoved++;
                if (!pagevec_add(&pvec, page)) {
-                       __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
                        spin_unlock_irq(&zone->lru_lock);
-                       pgdeactivate += pgmoved;
-                       pgmoved = 0;
                        if (buffer_heads_over_limit)
                                pagevec_strip(&pvec);
                        __pagevec_release(&pvec);

@@ -1315,9 +1311,8 @@ static void shrink_active_list(unsigned
                }
        }
        __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
-       pgdeactivate += pgmoved;
        __count_zone_vm_events(PGREFILL, zone, pgscanned);
-       __count_vm_events(PGDEACTIVATE, pgdeactivate);
+       __count_vm_events(PGDEACTIVATE, pgmoved);
        spin_unlock_irq(&zone->lru_lock);
        if (buffer_heads_over_limit)
                pagevec_strip(&pvec);
 
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Signature · 8 lines

Thanks,
Minchan Kim

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Rik van Riel

Acked-by on v1 1/1

2009-05-05 12:15 UTC #2 lore raw

In reply to Wu Fengguang

Quoted 4 lines · Wu Fengguang

This effectively lifts the unit of nr_inactive_* and pgdeactivate updates from PAGEVEC_SIZE=14 to SWAP_CLUSTER_MAX=32.
Signed-off-by Wu Fengguang <[email protected]>

Acked-by Rik van Riel <[email protected]>

Signature · 7 lines

All rights reversed.

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Johannes Weiner

maintainer

2009-05-05 12:35 UTC #3 lore raw

In reply to Wu Fengguang

Quoted 2 lines · Wu Fengguang

This effectively lifts the unit of nr_inactive_* and pgdeactivate updates from PAGEVEC_SIZE=14 to SWAP_CLUSTER_MAX=32.

For __zone_reclaim() it will be >= SWAP_CLUSTER_MAX, depending on the allocation order.

Hannes

Wu Fengguang

author Acked-by Rik van Riel Reviewed-by Minchan Kim

2009-05-05 13:12 UTC #4 lore raw

Quoted 6 lines · Johannes Weiner

Quoted 2 lines · Wu Fengguang
This effectively lifts the unit of nr_inactive_* and pgdeactivate updates from PAGEVEC_SIZE=14 to SWAP_CLUSTER_MAX=32.
For __zone_reclaim() it will be >= SWAP_CLUSTER_MAX, depending on the allocation order.

Thanks for pointing out this. Changelog updated accordingly.

I'd expect its impact to be negletable, because 1024 pages are not extraordinary large. But sure, that's much larger than 125 pages
- the maximum zone stats update threshold(zone_pcp->stat_threshold).

Thanks,
Fengguang
---
vmscan: ZVC updates in shrink_active_list() can be done once

This effectively lifts the unit of updates to nr_inactive_* and pgdeactivate from PAGEVEC_SIZE=14 to SWAP_CLUSTER_MAX=32, or MAX_ORDER_NR_PAGES=1024 for reclaim_zone().

CC Johannes Weiner <[email protected]>

Acked-by Rik van Riel <[email protected]>

Reviewed-by Minchan Kim <[email protected]>

Signed-off-by Wu Fengguang <[email protected]>

---
 mm/vmscan.c |   11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

mm/vmscan.c +3 -8

@@ -1228,7 +1228,6 @@ static void shrink_active_list(unsigned 
 			struct scan_control *sc, int priority, int file)
 {
 	unsigned long pgmoved;
-	int pgdeactivate = 0;
 	unsigned long pgscanned;
 	LIST_HEAD(l_hold);	/* The pages which were snipped off */
 	LIST_HEAD(l_inactive);

@@ -1257,7 +1256,7 @@ static void shrink_active_list(unsigned 
 		__mod_zone_page_state(zone, NR_ACTIVE_ANON, -pgmoved);
 	spin_unlock_irq(&zone->lru_lock);
 
-	pgmoved = 0;
+	pgmoved = 0;  /* count referenced (mapping) mapped pages */
 	while (!list_empty(&l_hold)) {
 		cond_resched();
 		page = lru_to_page(&l_hold);

@@ -1291,7 +1290,7 @@ static void shrink_active_list(unsigned 
 	 */
 	reclaim_stat->recent_rotated[!!file] += pgmoved;
 
-	pgmoved = 0;
+	pgmoved = 0;  /* count pages moved to inactive list */
 	while (!list_empty(&l_inactive)) {
 		page = lru_to_page(&l_inactive);
 		prefetchw_prev_lru_page(page, &l_inactive, flags);

@@ -1304,10 +1303,7 @@ static void shrink_active_list(unsigned 
 		mem_cgroup_add_lru_list(page, lru);
 		pgmoved++;
 		if (!pagevec_add(&pvec, page)) {
-			__mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
 			spin_unlock_irq(&zone->lru_lock);
-			pgdeactivate += pgmoved;
-			pgmoved = 0;
 			if (buffer_heads_over_limit)
 				pagevec_strip(&pvec);
 			__pagevec_release(&pvec);

@@ -1315,9 +1311,8 @@ static void shrink_active_list(unsigned 
 		}
 	}
 	__mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
-	pgdeactivate += pgmoved;
 	__count_zone_vm_events(PGREFILL, zone, pgscanned);
-	__count_vm_events(PGDEACTIVATE, pgdeactivate);
+	__count_vm_events(PGDEACTIVATE, pgmoved);
 	spin_unlock_irq(&zone->lru_lock);
 	if (buffer_heads_over_limit)
 		pagevec_strip(&pvec);