The patch titled
memcg: count the soft_limit reclaim in global background reclaim
has been added to the -mm tree. Its filename is
memcg-count-the-soft_limit-reclaim-in-global-background-reclaim.patch
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Subject: memcg: count the soft_limit reclaim in global background reclaim
From: Ying Han <yinghan@xxxxxxxxxx>
The global kswapd scans per-zone LRU and reclaims pages regardless of the
cgroup. It breaks memory isolation since one cgroup can end up reclaiming
pages from another cgroup. Instead we should rely on memcg-aware target
reclaim including per-memcg kswapd and soft_limit hierarchical reclaim under
memory pressure.
In the global background reclaim, we do soft reclaim before scanning the
per-zone LRU. However, the return value is ignored. This patch is the first
step to skip shrink_zone() if soft_limit reclaim does enough work.
This is part of the effort which tries to reduce reclaiming pages in global
LRU in memcg. The per-memcg background reclaim patchset further enhances the
per-cgroup targetting reclaim, which I should have V4 posted shortly.
Try running multiple memory intensive workloads within seperate memcgs. Watch
the counters of soft_steal in memory.stat.
$ cat /dev/cgroup/A/memory.stat | grep 'soft'
soft_steal 240000
soft_scan 240000
total_soft_steal 240000
total_soft_scan 240000
This patch:
In the global background reclaim, we do soft reclaim before scanning the
per-zone LRU. However, the return value is ignored.
We would like to skip shrink_zone() if soft_limit reclaim does enough
work. Also, we need to make the memory pressure balanced across per-memcg
zones, like the logic vm-core. This patch is the first step where we
start with counting the nr_scanned and nr_reclaimed from soft_limit
reclaim into the global scan_control.
Signed-off-by: Ying Han <yinghan@xxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxx>
Acked-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/memcontrol.h | 6 ++++--
include/linux/swap.h | 3 ++-
mm/memcontrol.c | 29 ++++++++++++++++++++---------
mm/vmscan.c | 16 +++++++++++++---
4 files changed, 39 insertions(+), 15 deletions(-)
diff -puN include/linux/memcontrol.h~memcg-count-the-soft_limit-reclaim-in-global-background-reclaim include/linux/memcontrol.h
--- a/include/linux/memcontrol.h~memcg-count-the-soft_limit-reclaim-in-global-background-reclaim
+++ a/include/linux/memcontrol.h
@@ -144,7 +144,8 @@ static inline void mem_cgroup_dec_page_s
}
unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
- gfp_t gfp_mask);
+ gfp_t gfp_mask,
+ unsigned long *total_scanned);
u64 mem_cgroup_get_limit(struct mem_cgroup *mem);
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
@@ -338,7 +339,8 @@ static inline void mem_cgroup_dec_page_s
static inline
unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
- gfp_t gfp_mask)
+ gfp_t gfp_mask,
+ unsigned long *total_scanned)
{
return 0;
}
diff -puN include/linux/swap.h~memcg-count-the-soft_limit-reclaim-in-global-background-reclaim include/linux/swap.h
--- a/include/linux/swap.h~memcg-count-the-soft_limit-reclaim-in-global-background-reclaim
+++ a/include/linux/swap.h
@@ -257,7 +257,8 @@ extern unsigned long try_to_free_mem_cgr
extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
gfp_t gfp_mask, bool noswap,
unsigned int swappiness,
- struct zone *zone);
+ struct zone *zone,
+ unsigned long *nr_scanned);
extern int __isolate_lru_page(struct page *page, int mode, int file);
extern unsigned long shrink_all_memory(unsigned long nr_pages);
extern int vm_swappiness;
diff -puN mm/memcontrol.c~memcg-count-the-soft_limit-reclaim-in-global-background-reclaim mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-count-the-soft_limit-reclaim-in-global-background-reclaim
+++ a/mm/memcontrol.c
@@ -1433,7 +1433,8 @@ mem_cgroup_select_victim(struct mem_cgro
static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
struct zone *zone,
gfp_t gfp_mask,
- unsigned long reclaim_options)
+ unsigned long reclaim_options,
+ unsigned long *total_scanned)
{
struct mem_cgroup *victim;
int ret, total = 0;
@@ -1442,6 +1443,7 @@ static int mem_cgroup_hierarchical_recla
bool shrink = reclaim_options & MEM_CGROUP_RECLAIM_SHRINK;
bool check_soft = reclaim_options & MEM_CGROUP_RECLAIM_SOFT;
unsigned long excess;
+ unsigned long nr_scanned;
excess = res_counter_soft_limit_excess(&root_mem->res) >> PAGE_SHIFT;
@@ -1484,10 +1486,12 @@ static int mem_cgroup_hierarchical_recla
continue;
}
/* we use swappiness of local cgroup */
- if (check_soft)
+ if (check_soft) {
ret = mem_cgroup_shrink_node_zone(victim, gfp_mask,
- noswap, get_swappiness(victim), zone);
- else
+ noswap, get_swappiness(victim), zone,
+ &nr_scanned);
+ *total_scanned += nr_scanned;
+ } else
ret = try_to_free_mem_cgroup_pages(victim, gfp_mask,
noswap, get_swappiness(victim));
css_put(&victim->css);
@@ -1928,7 +1932,7 @@ static int mem_cgroup_do_charge(struct m
return CHARGE_WOULDBLOCK;
ret = mem_cgroup_hierarchical_reclaim(mem_over_limit, NULL,
- gfp_mask, flags);
+ gfp_mask, flags, NULL);
if (mem_cgroup_margin(mem_over_limit) >= nr_pages)
return CHARGE_RETRY;
/*
@@ -3211,7 +3215,8 @@ static int mem_cgroup_resize_limit(struc
break;
mem_cgroup_hierarchical_reclaim(memcg, NULL, GFP_KERNEL,
- MEM_CGROUP_RECLAIM_SHRINK);
+ MEM_CGROUP_RECLAIM_SHRINK,
+ NULL);
curusage = res_counter_read_u64(&memcg->res, RES_USAGE);
/* Usage is reduced ? */
if (curusage >= oldusage)
@@ -3271,7 +3276,8 @@ static int mem_cgroup_resize_memsw_limit
mem_cgroup_hierarchical_reclaim(memcg, NULL, GFP_KERNEL,
MEM_CGROUP_RECLAIM_NOSWAP |
- MEM_CGROUP_RECLAIM_SHRINK);
+ MEM_CGROUP_RECLAIM_SHRINK,
+ NULL);
curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
/* Usage is reduced ? */
if (curusage >= oldusage)
@@ -3285,7 +3291,8 @@ static int mem_cgroup_resize_memsw_limit
}
unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
- gfp_t gfp_mask)
+ gfp_t gfp_mask,
+ unsigned long *total_scanned)
{
unsigned long nr_reclaimed = 0;
struct mem_cgroup_per_zone *mz, *next_mz = NULL;
@@ -3293,6 +3300,7 @@ unsigned long mem_cgroup_soft_limit_recl
int loop = 0;
struct mem_cgroup_tree_per_zone *mctz;
unsigned long long excess;
+ unsigned long nr_scanned;
if (order > 0)
return 0;
@@ -3311,10 +3319,13 @@ unsigned long mem_cgroup_soft_limit_recl
if (!mz)
break;
+ nr_scanned = 0;
reclaimed = mem_cgroup_hierarchical_reclaim(mz->mem, zone,
gfp_mask,
- MEM_CGROUP_RECLAIM_SOFT);
+ MEM_CGROUP_RECLAIM_SOFT,
+ &nr_scanned);
nr_reclaimed += reclaimed;
+ *total_scanned += nr_scanned;
spin_lock(&mctz->lock);
/*
diff -puN mm/vmscan.c~memcg-count-the-soft_limit-reclaim-in-global-background-reclaim mm/vmscan.c
--- a/mm/vmscan.c~memcg-count-the-soft_limit-reclaim-in-global-background-reclaim
+++ a/mm/vmscan.c
@@ -2147,9 +2147,11 @@ unsigned long try_to_free_pages(struct z
unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
gfp_t gfp_mask, bool noswap,
unsigned int swappiness,
- struct zone *zone)
+ struct zone *zone,
+ unsigned long *nr_scanned)
{
struct scan_control sc = {
+ .nr_scanned = 0,
.nr_to_reclaim = SWAP_CLUSTER_MAX,
.may_writepage = !laptop_mode,
.may_unmap = 1,
@@ -2158,6 +2160,7 @@ unsigned long mem_cgroup_shrink_node_zon
.order = 0,
.mem_cgroup = mem,
};
+
sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
@@ -2176,6 +2179,7 @@ unsigned long mem_cgroup_shrink_node_zon
trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
+ *nr_scanned = sc.nr_scanned;
return sc.nr_reclaimed;
}
@@ -2320,6 +2324,8 @@ static unsigned long balance_pgdat(pg_da
int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
unsigned long total_scanned;
struct reclaim_state *reclaim_state = current->reclaim_state;
+ unsigned long nr_soft_reclaimed;
+ unsigned long nr_soft_scanned;
struct scan_control sc = {
.gfp_mask = GFP_KERNEL,
.may_unmap = 1,
@@ -2409,11 +2415,15 @@ loop_again:
sc.nr_scanned = 0;
+ nr_soft_scanned = 0;
/*
* Call soft limit reclaim before calling shrink_zone.
- * For now we ignore the return value
*/
- mem_cgroup_soft_limit_reclaim(zone, order, sc.gfp_mask);
+ nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone,
+ order, sc.gfp_mask,
+ &nr_soft_scanned);
+ sc.nr_reclaimed += nr_soft_reclaimed;
+ total_scanned += nr_soft_scanned;
/*
* We put equal pressure on every zone, unless
_
Patches currently in -mm which might be from yinghan@xxxxxxxxxx are
memcg-count-the-soft_limit-reclaim-in-global-background-reclaim.patch
memcg-add-stats-to-monitor-soft_limit-reclaim.patch
add-the-pagefault-count-into-memcg-stats.patch
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