mm: memcontrol: basic memory statistics in cgroup2 memory controller

Provide a cgroup2 memory.stat that provides statistics on LRU memory
and fault event counters. More consumers and breakdowns will follow.

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

diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt
index f441564..65b3eac 100644 (file)
--- a/Documentation/cgroup-v2.txt
+++ b/Documentation/cgroup-v2.txt
@@ -819,6 +819,62 @@ PAGE_SIZE multiple when read back.
                the cgroup.  This may not exactly match the number of
                processes killed but should generally be close.
 
+  memory.stat
+
+       A read-only flat-keyed file which exists on non-root cgroups.
+
+       This breaks down the cgroup's memory footprint into different
+       types of memory, type-specific details, and other information
+       on the state and past events of the memory management system.
+
+       All memory amounts are in bytes.
+
+       The entries are ordered to be human readable, and new entries
+       can show up in the middle. Don't rely on items remaining in a
+       fixed position; use the keys to look up specific values!
+
+         anon
+
+               Amount of memory used in anonymous mappings such as
+               brk(), sbrk(), and mmap(MAP_ANONYMOUS)
+
+         file
+
+               Amount of memory used to cache filesystem data,
+               including tmpfs and shared memory.
+
+         file_mapped
+
+               Amount of cached filesystem data mapped with mmap()
+
+         file_dirty
+
+               Amount of cached filesystem data that was modified but
+               not yet written back to disk
+
+         file_writeback
+
+               Amount of cached filesystem data that was modified and
+               is currently being written back to disk
+
+         inactive_anon
+         active_anon
+         inactive_file
+         active_file
+         unevictable
+
+               Amount of memory, swap-backed and filesystem-backed,
+               on the internal memory management lists used by the
+               page reclaim algorithm
+
+         pgfault
+
+               Total number of page faults incurred
+
+         pgmajfault
+
+               Number of major page faults incurred
+
   memory.swap.current
 
        A read-only single value file which exists on non-root

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index bf35bff..98f4109 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2767,6 +2767,18 @@ static unsigned long tree_stat(struct mem_cgroup *memcg,
        return val;
 }
 
+static unsigned long tree_events(struct mem_cgroup *memcg,
+                                enum mem_cgroup_events_index idx)
+{
+       struct mem_cgroup *iter;
+       unsigned long val = 0;
+
+       for_each_mem_cgroup_tree(iter, memcg)
+               val += mem_cgroup_read_events(iter, idx);
+
+       return val;
+}
+
 static unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
 {
        unsigned long val;
@@ -5096,6 +5108,57 @@ static int memory_events_show(struct seq_file *m, void *v)
        return 0;
 }
 
+static int memory_stat_show(struct seq_file *m, void *v)
+{
+       struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+       int i;
+
+       /*
+        * Provide statistics on the state of the memory subsystem as
+        * well as cumulative event counters that show past behavior.
+        *
+        * This list is ordered following a combination of these gradients:
+        * 1) generic big picture -> specifics and details
+        * 2) reflecting userspace activity -> reflecting kernel heuristics
+        *
+        * Current memory state:
+        */
+
+       seq_printf(m, "anon %llu\n",
+                  (u64)tree_stat(memcg, MEM_CGROUP_STAT_RSS) * PAGE_SIZE);
+       seq_printf(m, "file %llu\n",
+                  (u64)tree_stat(memcg, MEM_CGROUP_STAT_CACHE) * PAGE_SIZE);
+
+       seq_printf(m, "file_mapped %llu\n",
+                  (u64)tree_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED) *
+                  PAGE_SIZE);
+       seq_printf(m, "file_dirty %llu\n",
+                  (u64)tree_stat(memcg, MEM_CGROUP_STAT_DIRTY) *
+                  PAGE_SIZE);
+       seq_printf(m, "file_writeback %llu\n",
+                  (u64)tree_stat(memcg, MEM_CGROUP_STAT_WRITEBACK) *
+                  PAGE_SIZE);
+
+       for (i = 0; i < NR_LRU_LISTS; i++) {
+               struct mem_cgroup *mi;
+               unsigned long val = 0;
+
+               for_each_mem_cgroup_tree(mi, memcg)
+                       val += mem_cgroup_nr_lru_pages(mi, BIT(i));
+               seq_printf(m, "%s %llu\n",
+                          mem_cgroup_lru_names[i], (u64)val * PAGE_SIZE);
+       }
+
+       /* Accumulated memory events */
+
+       seq_printf(m, "pgfault %lu\n",
+                  tree_events(memcg, MEM_CGROUP_EVENTS_PGFAULT));
+       seq_printf(m, "pgmajfault %lu\n",
+                  tree_events(memcg, MEM_CGROUP_EVENTS_PGMAJFAULT));
+
+       return 0;
+}
+
 static struct cftype memory_files[] = {
        {
                .name = "current",
@@ -5126,6 +5189,11 @@ static struct cftype memory_files[] = {
                .file_offset = offsetof(struct mem_cgroup, events_file),
                .seq_show = memory_events_show,
        },
+       {
+               .name = "stat",
+               .flags = CFTYPE_NOT_ON_ROOT,
+               .seq_show = memory_stat_show,
+       },
        { }     /* terminate */
 };