From f3344adf38bdb3107d40483dd9501215ad40edce Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Wed, 24 Feb 2021 12:03:15 -0800 Subject: mm: memcontrol: optimize per-lruvec stats counter memory usage The vmstat threshold is 32 (MEMCG_CHARGE_BATCH), Actually the threshold can be as big as MEMCG_CHARGE_BATCH * PAGE_SIZE. It still fits into s32. So introduce struct batched_lruvec_stat to optimize memory usage. The size of struct lruvec_stat is 304 bytes on 64 bit systems. As it is a per-cpu structure. So with this patch, we can save 304 / 2 * ncpu bytes per-memcg per-node where ncpu is the number of the possible CPU. If there are c memory cgroup (include dying cgroup) and n NUMA node in the system. Finally, we can save (152 * ncpu * c * n) bytes. [akpm@linux-foundation.org: fix typo in comment] Link: https://lkml.kernel.org/r/20201210042121.39665-1-songmuchun@bytedance.com Signed-off-by: Muchun Song Reviewed-by: Shakeel Butt Cc: Johannes Weiner Cc: Michal Hocko Cc: Vladimir Davydov Cc: Shakeel Butt Cc: Roman Gushchin Cc: Stephen Rothwell Cc: Chris Down Cc: Yafang Shao Cc: Wei Yang Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/memcontrol.h | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 7a4dd1cb19fe..41bbf71edd9f 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -92,6 +92,10 @@ struct lruvec_stat { long count[NR_VM_NODE_STAT_ITEMS]; }; +struct batched_lruvec_stat { + s32 count[NR_VM_NODE_STAT_ITEMS]; +}; + /* * Bitmap of shrinker::id corresponding to memcg-aware shrinkers, * which have elements charged to this memcg. @@ -107,11 +111,17 @@ struct memcg_shrinker_map { struct mem_cgroup_per_node { struct lruvec lruvec; - /* Legacy local VM stats */ + /* + * Legacy local VM stats. This should be struct lruvec_stat and + * cannot be optimized to struct batched_lruvec_stat. Because + * the threshold of the lruvec_stat_cpu can be as big as + * MEMCG_CHARGE_BATCH * PAGE_SIZE. It can fit into s32. But this + * filed has no upper limit. + */ struct lruvec_stat __percpu *lruvec_stat_local; /* Subtree VM stats (batched updates) */ - struct lruvec_stat __percpu *lruvec_stat_cpu; + struct batched_lruvec_stat __percpu *lruvec_stat_cpu; atomic_long_t lruvec_stat[NR_VM_NODE_STAT_ITEMS]; unsigned long lru_zone_size[MAX_NR_ZONES][NR_LRU_LISTS]; -- cgit v1.2.3-59-g8ed1b