[PATCH 02/10] mm: update_lru_size do the __mod_zone_page_state

Hugh Dickins
2016-04-05T20:42:04Z

Konstantin Khlebnikov pointed out (nearly four years ago, when lumpy
reclaim was removed) that lru_size can be updated by -nr_taken once
per call to isolate_lru_pages(), instead of page by page.

Update it inside isolate_lru_pages(), or at its two callsites? I
chose to update it at the callsites, rearranging and grouping the
updates by nr_taken and nr_scanned together in both.

With one exception, mem_cgroup_update_lru_size(,lru,) is then used
where __mod_zone_page_state(,NR_LRU_BASE+lru,) is used; and we shall
be adding some more calls in a future commit. Make the code a little
smaller and simpler by incorporating stat update in lru_size update.

The exception was move_active_pages_to_lru(), which aggregated the
pgmoved stat update separately from the individual lru_size updates;
but I still think this a simplification worth making.

However, the __mod_zone_page_state is not peculiar to mem_cgroups: so
better use the name update_lru_size, calls mem_cgroup_update_lru_size
when CONFIG_MEMCG.

Signed-off-by: Hugh Dickins <hughd@google.com>
---
include/linux/memcontrol.h | 6 ------
include/linux/mm_inline.h | 24 ++++++++++++++++++------
mm/memcontrol.c | 2 ++
mm/vmscan.c | 23 ++++++++++-------------
4 files changed, 30 insertions(+), 25 deletions(-)

--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -658,12 +658,6 @@ mem_cgroup_get_lru_size(struct lruvec *l
return 0;
}

-static inline void
-mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
- int increment)
-{
-}
-
static inline unsigned long
mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
int nid, unsigned int lru_mask)
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -22,22 +22,34 @@ static inline int page_is_file_cache(str
return !PageSwapBacked(page);
}

+static __always_inline void __update_lru_size(struct lruvec *lruvec,
+ enum lru_list lru, int nr_pages)
+{
+ __mod_zone_page_state(lruvec_zone(lruvec), NR_LRU_BASE + lru, nr_pages);
+}
+
+static __always_inline void update_lru_size(struct lruvec *lruvec,
+ enum lru_list lru, int nr_pages)
+{
+#ifdef CONFIG_MEMCG
+ mem_cgroup_update_lru_size(lruvec, lru, nr_pages);
+#else
+ __update_lru_size(lruvec, lru, nr_pages);
+#endif
+}
+
static __always_inline void add_page_to_lru_list(struct page *page,
struct lruvec *lruvec, enum lru_list lru)
{
- int nr_pages = hpage_nr_pages(page);
- mem_cgroup_update_lru_size(lruvec, lru, nr_pages);
+ update_lru_size(lruvec, lru, hpage_nr_pages(page));
list_add(&page->lru, &lruvec->lists[lru]);
- __mod_zone_page_state(lruvec_zone(lruvec), NR_LRU_BASE + lru, nr_pages);
}

static __always_inline void del_page_from_lru_list(struct page *page,
struct lruvec *lruvec, enum lru_list lru)
{
- int nr_pages = hpage_nr_pages(page);
list_del(&page->lru);
- mem_cgroup_update_lru_size(lruvec, lru, -nr_pages);
- __mod_zone_page_state(lruvec_zone(lruvec), NR_LRU_BASE + lru, -nr_pages);
+ update_lru_size(lruvec, lru, -hpage_nr_pages(page));
}

/**
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1034,6 +1034,8 @@ void mem_cgroup_update_lru_size(struct l
long size;
bool empty;

+ __update_lru_size(lruvec, lru, nr_pages);
+
if (mem_cgroup_disabled())
return;

--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1374,7 +1374,6 @@ static unsigned long isolate_lru_pages(u
for (scan = 0; scan < nr_to_scan && nr_taken < nr_to_scan &&
!list_empty(src); scan++) {
struct page *page;
- int nr_pages;

page = lru_to_page(src);
prefetchw_prev_lru_page(page, src, flags);
@@ -1383,10 +1382,8 @@ static unsigned long isolate_lru_pages(u

switch (__isolate_lru_page(page, mode)) {
case 0:
- nr_pages = hpage_nr_pages(page);
- mem_cgroup_update_lru_size(lruvec, lru, -nr_pages);
+ nr_taken += hpage_nr_pages(page);
list_move(&page->lru, dst);
- nr_taken += nr_pages;
break;

case -EBUSY:
@@ -1602,8 +1599,9 @@ shrink_inactive_list(unsigned long nr_to
nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &page_list,
&nr_scanned, sc, isolate_mode, lru);

- __mod_zone_page_state(zone, NR_LRU_BASE + lru, -nr_taken);
+ update_lru_size(lruvec, lru, -nr_taken);
__mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken);
+ reclaim_stat->recent_scanned[file] += nr_taken;

if (global_reclaim(sc)) {
__mod_zone_page_state(zone, NR_PAGES_SCANNED, nr_scanned);
@@ -1624,8 +1622,6 @@ shrink_inactive_list(unsigned long nr_to

spin_lock_irq(&zone->lru_lock);

- reclaim_stat->recent_scanned[file] += nr_taken;
-
if (global_reclaim(sc)) {
if (current_is_kswapd())
__count_zone_vm_events(PGSTEAL_KSWAPD, zone,
@@ -1742,7 +1738,7 @@ static void move_active_pages_to_lru(str
SetPageLRU(page);

nr_pages = hpage_nr_pages(page);
- mem_cgroup_update_lru_size(lruvec, lru, nr_pages);
+ update_lru_size(lruvec, lru, nr_pages);
list_move(&page->lru, &lruvec->lists[lru]);
pgmoved += nr_pages;

@@ -1760,7 +1756,7 @@ static void move_active_pages_to_lru(str
list_add(&page->lru, pages_to_free);
}
}
- __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
+
if (!is_active_lru(lru))
__count_vm_events(PGDEACTIVATE, pgmoved);
}
@@ -1794,14 +1790,15 @@ static void shrink_active_list(unsigned

nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &l_hold,
&nr_scanned, sc, isolate_mode, lru);
- if (global_reclaim(sc))
- __mod_zone_page_state(zone, NR_PAGES_SCANNED, nr_scanned);

+ update_lru_size(lruvec, lru, -nr_taken);
+ __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken);
reclaim_stat->recent_scanned[file] += nr_taken;

+ if (global_reclaim(sc))
+ __mod_zone_page_state(zone, NR_PAGES_SCANNED, nr_scanned);
__count_zone_vm_events(PGREFILL, zone, nr_scanned);
- __mod_zone_page_state(zone, NR_LRU_BASE + lru, -nr_taken);
- __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken);
+
spin_unlock_irq(&zone->lru_lock);

while (!list_empty(&l_hold)) {