[PATCH -mm] vmscan: move reclaim_state handling to shrink_slab
From: Vladimir Davydov
Date: Wed Jan 14 2015 - 08:56:11 EST
current->reclaim_state is only used to count the number of slab pages
reclaimed by shrink_slab(). So instead of initializing it before we are
going to call try_to_free_pages() or shrink_zone(), let's set in
directly in shrink_slab().
This patch also makes shrink_slab() return the number of reclaimed slab
pages (obtained from reclaim_state) instead of the number of reclaimed
objects, because the latter is not of much use - it was only checked by
drop_slab() to decide whether it should continue reclaim or abort. The
number of reclaimed pages is more appropriate, because it also can be
used by shrink_zone() to accumulate scan_control->nr_reclaimed.
Note that after this patch try_to_free_mem_cgroup_pages() will count not
only reclaimed user pages, but also slab pages, which is expected,
because it can reclaim kmem from kmem-active sub cgroups.
Suggested-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
---
mm/page_alloc.c | 4 ---
mm/vmscan.c | 73 ++++++++++++++++++++-----------------------------------
2 files changed, 27 insertions(+), 50 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e1963ea0684a..f528e4ba91b5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2448,7 +2448,6 @@ static int
__perform_reclaim(gfp_t gfp_mask, unsigned int order, struct zonelist *zonelist,
nodemask_t *nodemask)
{
- struct reclaim_state reclaim_state;
int progress;
cond_resched();
@@ -2457,12 +2456,9 @@ __perform_reclaim(gfp_t gfp_mask, unsigned int order, struct zonelist *zonelist,
cpuset_memory_pressure_bump();
current->flags |= PF_MEMALLOC;
lockdep_set_current_reclaim_state(gfp_mask);
- reclaim_state.reclaimed_slab = 0;
- current->reclaim_state = &reclaim_state;
progress = try_to_free_pages(zonelist, order, gfp_mask, nodemask);
- current->reclaim_state = NULL;
lockdep_clear_current_reclaim_state();
current->flags &= ~PF_MEMALLOC;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 16f3e45742d6..9b61fcb0b45b 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -229,10 +229,10 @@ EXPORT_SYMBOL(unregister_shrinker);
#define SHRINK_BATCH 128
-static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
- struct shrinker *shrinker,
- unsigned long nr_scanned,
- unsigned long nr_eligible)
+static void do_shrink_slab(struct shrink_control *shrinkctl,
+ struct shrinker *shrinker,
+ unsigned long nr_scanned,
+ unsigned long nr_eligible)
{
unsigned long freed = 0;
unsigned long long delta;
@@ -246,7 +246,7 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
freeable = shrinker->count_objects(shrinker, shrinkctl);
if (freeable == 0)
- return 0;
+ return;
/*
* copy the current shrinker scan count into a local variable
@@ -337,7 +337,6 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
new_nr = atomic_long_read(&shrinker->nr_deferred[nid]);
trace_mm_shrink_slab_end(shrinker, nid, freed, nr, new_nr, total_scan);
- return freed;
}
/**
@@ -367,15 +366,17 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
* the ->seeks setting of the shrink function, which indicates the
* cost to recreate an object relative to that of an LRU page.
*
- * Returns the number of reclaimed slab objects.
+ * Returns the number of reclaimed slab pages.
*/
static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
struct mem_cgroup *memcg,
unsigned long nr_scanned,
unsigned long nr_eligible)
{
+ struct reclaim_state reclaim_state = {
+ .reclaimed_slab = 0,
+ };
struct shrinker *shrinker;
- unsigned long freed = 0;
if (memcg && !memcg_kmem_is_active(memcg))
return 0;
@@ -384,16 +385,12 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
nr_scanned = SWAP_CLUSTER_MAX;
if (!down_read_trylock(&shrinker_rwsem)) {
- /*
- * If we would return 0, our callers would understand that we
- * have nothing else to shrink and give up trying. By returning
- * 1 we keep it going and assume we'll be able to shrink next
- * time.
- */
- freed = 1;
- goto out;
+ cond_resched();
+ return 0;
}
+ current->reclaim_state = &reclaim_state;
+
list_for_each_entry(shrinker, &shrinker_list, list) {
struct shrink_control sc = {
.gfp_mask = gfp_mask,
@@ -407,13 +404,15 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
sc.nid = 0;
- freed += do_shrink_slab(&sc, shrinker, nr_scanned, nr_eligible);
+ do_shrink_slab(&sc, shrinker, nr_scanned, nr_eligible);
}
+ current->reclaim_state = NULL;
+
up_read(&shrinker_rwsem);
-out:
+
cond_resched();
- return freed;
+ return reclaim_state.reclaimed_slab;
}
void drop_slab_node(int nid)
@@ -428,7 +427,7 @@ void drop_slab_node(int nid)
freed += shrink_slab(GFP_KERNEL, nid, memcg,
1000, 1000);
} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
- } while (freed > 10);
+ } while (freed);
}
void drop_slab(void)
@@ -2339,7 +2338,6 @@ static inline bool should_continue_reclaim(struct zone *zone,
static bool shrink_zone(struct zone *zone, struct scan_control *sc,
bool is_classzone)
{
- struct reclaim_state *reclaim_state = current->reclaim_state;
unsigned long nr_reclaimed, nr_scanned;
bool reclaimable = false;
@@ -2369,9 +2367,10 @@ static bool shrink_zone(struct zone *zone, struct scan_control *sc,
zone_lru_pages += lru_pages;
if (memcg && is_classzone)
- shrink_slab(sc->gfp_mask, zone_to_nid(zone),
- memcg, sc->nr_scanned - scanned,
- lru_pages);
+ sc->nr_reclaimed += shrink_slab(sc->gfp_mask,
+ zone_to_nid(zone), memcg,
+ sc->nr_scanned - scanned,
+ lru_pages);
/*
* Direct reclaim and kswapd have to scan all memory
@@ -2396,14 +2395,10 @@ static bool shrink_zone(struct zone *zone, struct scan_control *sc,
* 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;
- }
+ sc->nr_reclaimed += shrink_slab(sc->gfp_mask,
+ zone_to_nid(zone), NULL,
+ sc->nr_scanned - nr_scanned,
+ zone_lru_pages);
vmpressure(sc->gfp_mask, sc->target_mem_cgroup,
sc->nr_scanned - nr_scanned,
@@ -3367,17 +3362,12 @@ static int kswapd(void *p)
int balanced_classzone_idx;
pg_data_t *pgdat = (pg_data_t*)p;
struct task_struct *tsk = current;
-
- struct reclaim_state reclaim_state = {
- .reclaimed_slab = 0,
- };
const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
lockdep_set_current_reclaim_state(GFP_KERNEL);
if (!cpumask_empty(cpumask))
set_cpus_allowed_ptr(tsk, cpumask);
- current->reclaim_state = &reclaim_state;
/*
* Tell the memory management that we're a "memory allocator",
@@ -3449,7 +3439,6 @@ static int kswapd(void *p)
}
tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD);
- current->reclaim_state = NULL;
lockdep_clear_current_reclaim_state();
return 0;
@@ -3492,7 +3481,6 @@ void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
*/
unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
{
- struct reclaim_state reclaim_state;
struct scan_control sc = {
.nr_to_reclaim = nr_to_reclaim,
.gfp_mask = GFP_HIGHUSER_MOVABLE,
@@ -3508,12 +3496,9 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
p->flags |= PF_MEMALLOC;
lockdep_set_current_reclaim_state(sc.gfp_mask);
- reclaim_state.reclaimed_slab = 0;
- p->reclaim_state = &reclaim_state;
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
- p->reclaim_state = NULL;
lockdep_clear_current_reclaim_state();
p->flags &= ~PF_MEMALLOC;
@@ -3678,7 +3663,6 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
/* Minimum pages needed in order to stay on node */
const unsigned long nr_pages = 1 << order;
struct task_struct *p = current;
- struct reclaim_state reclaim_state;
struct scan_control sc = {
.nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
.gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)),
@@ -3697,8 +3681,6 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
*/
p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
lockdep_set_current_reclaim_state(gfp_mask);
- reclaim_state.reclaimed_slab = 0;
- p->reclaim_state = &reclaim_state;
if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) {
/*
@@ -3710,7 +3692,6 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
} while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0);
}
- p->reclaim_state = NULL;
current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
lockdep_clear_current_reclaim_state();
return sc.nr_reclaimed >= nr_pages;
--
1.7.10.4
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