mm: memcontrol: make tree_{stat,events} fetch all stats

Currently, tree_{stat,events} helpers can only get one stat index at a
time, so when there are a lot of stats to be reported one has to call it
over and over again (see memory_stat_show).  This is neither effective,
nor does it look good.  Instead, let's make these helpers take a
snapshot of all available counters.

Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 39 insertions, 28 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5c9d45e4c739..430266071c36 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2717,39 +2717,48 @@ static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css,
         return retval;
 }
 
-static unsigned long tree_stat(struct mem_cgroup *memcg,
-                               enum mem_cgroup_stat_index idx)
+static void tree_stat(struct mem_cgroup *memcg, unsigned long *stat)
 {
         struct mem_cgroup *iter;
-        unsigned long val = 0;
+        int i;
 
-        for_each_mem_cgroup_tree(iter, memcg)
-                val += mem_cgroup_read_stat(iter, idx);
+        memset(stat, 0, sizeof(*stat) * MEMCG_NR_STAT);
 
-        return val;
+        for_each_mem_cgroup_tree(iter, memcg) {
+                for (i = 0; i < MEMCG_NR_STAT; i++)
+                        stat[i] += mem_cgroup_read_stat(iter, i);
+        }
 }
 
-static unsigned long tree_events(struct mem_cgroup *memcg,
-                                 enum mem_cgroup_events_index idx)
+static void tree_events(struct mem_cgroup *memcg, unsigned long *events)
 {
         struct mem_cgroup *iter;
-        unsigned long val = 0;
+        int i;
 
-        for_each_mem_cgroup_tree(iter, memcg)
-                val += mem_cgroup_read_events(iter, idx);
+        memset(events, 0, sizeof(*events) * MEMCG_NR_EVENTS);
 
-        return val;
+        for_each_mem_cgroup_tree(iter, memcg) {
+                for (i = 0; i < MEMCG_NR_EVENTS; i++)
+                        events[i] += mem_cgroup_read_events(iter, i);
+        }
 }
 
 static unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
 {
-        unsigned long val;
+        unsigned long val = 0;
 
         if (mem_cgroup_is_root(memcg)) {
-                val = tree_stat(memcg, MEM_CGROUP_STAT_CACHE);
-                val += tree_stat(memcg, MEM_CGROUP_STAT_RSS);
-                if (swap)
-                        val += tree_stat(memcg, MEM_CGROUP_STAT_SWAP);
+                struct mem_cgroup *iter;
+
+                for_each_mem_cgroup_tree(iter, memcg) {
+                        val += mem_cgroup_read_stat(iter,
+                                        MEM_CGROUP_STAT_CACHE);
+                        val += mem_cgroup_read_stat(iter,
+                                        MEM_CGROUP_STAT_RSS);
+                        if (swap)
+                                val += mem_cgroup_read_stat(iter,
+                                                MEM_CGROUP_STAT_SWAP);
+                }
         } else {
                 if (!swap)
                         val = page_counter_read(&memcg->memory);
@@ -5075,6 +5084,8 @@ static int memory_events_show(struct seq_file *m, void *v)
 static int memory_stat_show(struct seq_file *m, void *v)
 {
         struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+        unsigned long stat[MEMCG_NR_STAT];
+        unsigned long events[MEMCG_NR_EVENTS];
         int i;
 
         /*
@@ -5088,22 +5099,22 @@ static int memory_stat_show(struct seq_file *m, void *v)
          * Current memory state:
          */
 
+        tree_stat(memcg, stat);
+        tree_events(memcg, events);
+
         seq_printf(m, "anon %llu\n",
-                   (u64)tree_stat(memcg, MEM_CGROUP_STAT_RSS) * PAGE_SIZE);
+                   (u64)stat[MEM_CGROUP_STAT_RSS] * PAGE_SIZE);
         seq_printf(m, "file %llu\n",
-                   (u64)tree_stat(memcg, MEM_CGROUP_STAT_CACHE) * PAGE_SIZE);
+                   (u64)stat[MEM_CGROUP_STAT_CACHE] * PAGE_SIZE);
         seq_printf(m, "sock %llu\n",
-                   (u64)tree_stat(memcg, MEMCG_SOCK) * PAGE_SIZE);
+                   (u64)stat[MEMCG_SOCK] * PAGE_SIZE);
 
         seq_printf(m, "file_mapped %llu\n",
-                   (u64)tree_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED) *
-                   PAGE_SIZE);
+                   (u64)stat[MEM_CGROUP_STAT_FILE_MAPPED] * PAGE_SIZE);
         seq_printf(m, "file_dirty %llu\n",
-                   (u64)tree_stat(memcg, MEM_CGROUP_STAT_DIRTY) *
-                   PAGE_SIZE);
+                   (u64)stat[MEM_CGROUP_STAT_DIRTY] * PAGE_SIZE);
         seq_printf(m, "file_writeback %llu\n",
-                   (u64)tree_stat(memcg, MEM_CGROUP_STAT_WRITEBACK) *
-                   PAGE_SIZE);
+                   (u64)stat[MEM_CGROUP_STAT_WRITEBACK] * PAGE_SIZE);
 
         for (i = 0; i < NR_LRU_LISTS; i++) {
                 struct mem_cgroup *mi;
@@ -5118,9 +5129,9 @@ static int memory_stat_show(struct seq_file *m, void *v)
         /* Accumulated memory events */
 
         seq_printf(m, "pgfault %lu\n",
-                   tree_events(memcg, MEM_CGROUP_EVENTS_PGFAULT));
+                   events[MEM_CGROUP_EVENTS_PGFAULT]);
         seq_printf(m, "pgmajfault %lu\n",
-                   tree_events(memcg, MEM_CGROUP_EVENTS_PGMAJFAULT));
+                   events[MEM_CGROUP_EVENTS_PGMAJFAULT]);
 
         return 0;
 }