[PATCH 02/14] mm: vmscan: simplify memcg vs. global shrinker invocation

Johannes Weiner
2015-11-12T23:47:33Z

Letting shrink_slab() handle the root_mem_cgroup, and implicitely the
!CONFIG_MEMCG case, allows shrink_zone() to invoke the shrinkers
unconditionally from within the memcg iteration loop.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
---
include/linux/memcontrol.h | 2 ++
mm/vmscan.c | 31 ++++++++++++++++---------------
2 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 9a7a24a..251bb51 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -502,6 +502,8 @@ void mem_cgroup_split_huge_fixup(struct page *head);
#else /* CONFIG_MEMCG */
struct mem_cgroup;

+#define root_mem_cgroup NULL
+
static inline void mem_cgroup_events(struct mem_cgroup *memcg,
enum mem_cgroup_events_index idx,
unsigned int nr)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index a4507ec..e4f5b3c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -411,6 +411,10 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
struct shrinker *shrinker;
unsigned long freed = 0;

+ /* Global shrinker mode */
+ if (memcg == root_mem_cgroup)
+ memcg = NULL;
+
if (memcg && !memcg_kmem_is_active(memcg))
return 0;

@@ -2410,11 +2414,22 @@ static bool shrink_zone(struct zone *zone, struct scan_control *sc,
shrink_lruvec(lruvec, swappiness, sc, &lru_pages);
zone_lru_pages += lru_pages;

- if (memcg && is_classzone)
+ /*
+ * Shrink the slab caches in the same proportion that
+ * the eligible LRU pages were scanned.
+ */
+ if (is_classzone) {
shrink_slab(sc->gfp_mask, zone_to_nid(zone),
memcg, sc->nr_scanned - scanned,
lru_pages);

+ if (reclaim_state) {
+ sc->nr_reclaimed +=
+ reclaim_state->reclaimed_slab;
+ reclaim_state->reclaimed_slab = 0;
+ }
+ }
+
/*
* Direct reclaim and kswapd have to scan all memory
* cgroups to fulfill the overall scan target for the
@@ -2432,20 +2447,6 @@ static bool shrink_zone(struct zone *zone, struct scan_control *sc,
}
} while ((memcg = mem_cgroup_iter(root, memcg, &reclaim)));

- /*
- * Shrink the slab caches in the same proportion that
- * the eligible LRU pages were scanned.
- */
- if (global_reclaim(sc) && is_classzone)
- shrink_slab(sc->gfp_mask, zone_to_nid(zone), NULL,
- sc->nr_scanned - nr_scanned,
- zone_lru_pages);
-
- if (reclaim_state) {
- sc->nr_reclaimed += reclaim_state->reclaimed_slab;
- reclaim_state->reclaimed_slab = 0;
- }
-
vmpressure(sc->gfp_mask, sc->target_mem_cgroup,
sc->nr_scanned - nr_scanned,
sc->nr_reclaimed - nr_reclaimed);
--
2.6.2