From 0ae5e89c60c9eb87da36a2614836bc434b0ec2ad Mon Sep 17 00:00:00 2001 From: Ying Han Date: Thu, 26 May 2011 16:25:25 -0700 Subject: [PATCH] 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 Cc: KOSAKI Motohiro Cc: Minchan Kim Cc: Rik van Riel Cc: Mel Gorman Cc: KAMEZAWA Hiroyuki Cc: Balbir Singh Acked-by: Daisuke Nishimura Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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 --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 5e9840f5098..0629121f2c0 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -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; } diff --git a/include/linux/swap.h b/include/linux/swap.h index a5c6da5d8df..384eb5fe530 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -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; diff --git a/mm/memcontrol.c b/mm/memcontrol.c index fc259926c17..e41a6c26f1e 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -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); /* diff --git a/mm/vmscan.c b/mm/vmscan.c index 7e0116150dc..9ce6ec84328 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -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