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memcg: count the soft_limit reclaim in global background reclaim 

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@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Ying Han 2011-05-26 16:25:25 -07:00 committed by Linus Torvalds
parent f042e707ee
commit 0ae5e89c60
4 changed files with 39 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/memcontrol.h
View File

@ -144,7 +144,8 @@ static inline void mem_cgroup_dec_page_stat(struct page *page,
}
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_stat(struct page *page,
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;
}

3
include/linux/swap.h
View File

@ -257,7 +257,8 @@ extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
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;

29
mm/memcontrol.c
View File

@ -1433,7 +1433,8 @@ mem_cgroup_select_victim(struct mem_cgroup *root_mem)
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_reclaim(struct mem_cgroup *root_mem,
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_reclaim(struct mem_cgroup *root_mem,
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 mem_cgroup *mem, gfp_t gfp_mask,
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(struct mem_cgroup *memcg,
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(struct mem_cgroup *memcg,
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(struct mem_cgroup *memcg,
}
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_reclaim(struct zone *zone, int order,
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_reclaim(struct zone *zone, int order,
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);
/*

16
mm/vmscan.c
View File

@ -2171,9 +2171,11 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
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,
@ -2182,6 +2184,7 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
.order = 0,
.mem_cgroup = mem,
};
sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
@ -2200,6 +2203,7 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
*nr_scanned = sc.nr_scanned;
return sc.nr_reclaimed;
}
@ -2347,6 +2351,8 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
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,
@ -2439,11 +2445,15 @@ 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