From: Shakeel Butt shakeelb@google.com
mainline inclusion from mainline-v5.8-rc1 commit dd8657b6c1cb5e65b13445b4a038736e81cf80ea category: bugfix CVE: NA
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Currently reading memory.numa_stat traverses the underlying memcg tree multiple times to accumulate the stats to present the hierarchical view of the memcg tree. However the kernel already maintains the hierarchical view of the stats and use it in memory.stat. Just use the same mechanism in memory.numa_stat as well.
I ran a simple benchmark which reads root_mem_cgroup's memory.numa_stat file in the presense of 10000 memcgs. The results are:
Without the patch: $ time cat /dev/cgroup/memory/memory.numa_stat > /dev/null
real 0m0.700s user 0m0.001s sys 0m0.697s
With the patch: $ time cat /dev/cgroup/memory/memory.numa_stat > /dev/null
real 0m0.001s user 0m0.001s sys 0m0.000s
[akpm@linux-foundation.org: avoid forcing out-of-line code generation] Signed-off-by: Shakeel Butt shakeelb@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Reviewed-by: Andrew Morton akpm@linux-foundation.org Acked-by: Johannes Weiner hannes@cmpxchg.org Cc: Roman Gushchin guro@fb.com Cc: Michal Hocko mhocko@kernel.org Link: http://lkml.kernel.org/r/20200304022058.248270-1-shakeelb@google.com Signed-off-by: Linus Torvalds torvalds@linux-foundation.org
Conflicts: mm/memcontrol.c
Signed-off-by: Jing Xiangfeng jingxiangfeng@huawei.com Reviewed-by: Kefeng Wang wangkefeng.wang@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- mm/memcontrol.c | 51 +++++++++++++++++++++++++------------------------ 1 file changed, 26 insertions(+), 25 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index ef742a42f105f..3f824fd2b6609 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3825,7 +3825,7 @@ int sysctl_memcg_qos_handler(struct ctl_table *table, int write, #define LRU_ALL ((1 << NR_LRU_LISTS) - 1)
static unsigned long mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg, - int nid, unsigned int lru_mask) + int nid, unsigned int lru_mask, bool tree) { struct lruvec *lruvec = mem_cgroup_lruvec(NODE_DATA(nid), memcg); unsigned long nr = 0; @@ -3836,13 +3836,17 @@ static unsigned long mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg, for_each_lru(lru) { if (!(BIT(lru) & lru_mask)) continue; - nr += lruvec_page_state_local(lruvec, NR_LRU_BASE + lru); + if (tree) + nr += lruvec_page_state(lruvec, NR_LRU_BASE + lru); + else + nr += lruvec_page_state_local(lruvec, NR_LRU_BASE + lru); } return nr; }
static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg, - unsigned int lru_mask) + unsigned int lru_mask, + bool tree) { unsigned long nr = 0; enum lru_list lru; @@ -3850,7 +3854,10 @@ static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg, for_each_lru(lru) { if (!(BIT(lru) & lru_mask)) continue; - nr += memcg_page_state_local(memcg, NR_LRU_BASE + lru); + if (tree) + nr += memcg_page_state(memcg, NR_LRU_BASE + lru); + else + nr += memcg_page_state_local(memcg, NR_LRU_BASE + lru); } return nr; } @@ -3870,34 +3877,28 @@ static int memcg_numa_stat_show(struct seq_file *m, void *v) }; const struct numa_stat *stat; int nid; - unsigned long nr; struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) { - nr = mem_cgroup_nr_lru_pages(memcg, stat->lru_mask); - seq_printf(m, "%s=%lu", stat->name, nr); - for_each_node_state(nid, N_MEMORY) { - nr = mem_cgroup_node_nr_lru_pages(memcg, nid, - stat->lru_mask); - seq_printf(m, " N%d=%lu", nid, nr); - } + seq_printf(m, "%s=%lu", stat->name, + mem_cgroup_nr_lru_pages(memcg, stat->lru_mask, + false)); + for_each_node_state(nid, N_MEMORY) + seq_printf(m, " N%d=%lu", nid, + mem_cgroup_node_nr_lru_pages(memcg, nid, + stat->lru_mask, false)); seq_putc(m, '\n'); }
for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) { - struct mem_cgroup *iter; - - nr = 0; - for_each_mem_cgroup_tree(iter, memcg) - nr += mem_cgroup_nr_lru_pages(iter, stat->lru_mask); - seq_printf(m, "hierarchical_%s=%lu", stat->name, nr); - for_each_node_state(nid, N_MEMORY) { - nr = 0; - for_each_mem_cgroup_tree(iter, memcg) - nr += mem_cgroup_node_nr_lru_pages( - iter, nid, stat->lru_mask); - seq_printf(m, " N%d=%lu", nid, nr); - } + + seq_printf(m, "hierarchical_%s=%lu", stat->name, + mem_cgroup_nr_lru_pages(memcg, stat->lru_mask, + true)); + for_each_node_state(nid, N_MEMORY) + seq_printf(m, " N%d=%lu", nid, + mem_cgroup_node_nr_lru_pages(memcg, nid, + stat->lru_mask, true)); seq_putc(m, '\n'); }
-
Yang Yingliang