[patch 4/4] mm: memcontrol: add memory.vmstat to default hierarchy

[Johannes Weiner <hannes@cmpxchg.org>]

Provide basic per-memcg vmstat-style statistics on LRU sizes,
allocated and freed pages, major and minor faults.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 Documentation/cgroups/unified-hierarchy.txt |  8 ++++++
 mm/memcontrol.c                             | 40 +++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/Documentation/cgroups/unified-hierarchy.txt b/Documentation/cgroups/unified-hierarchy.txt
index ef1db728a035..512e9a2b2e06 100644
--- a/Documentation/cgroups/unified-hierarchy.txt
+++ b/Documentation/cgroups/unified-hierarchy.txt
@@ -384,6 +384,14 @@ that purpose, a hard upper limit can be set through 'memory.max'.
 - memory.usage_in_bytes is renamed to memory.current to be in line
   with the new limit naming scheme
 
+- memory.stat has been replaced by memory.vmstat, which provides
+  page-based statistics in the style of /proc/vmstat.
+
+  As cgroups are now always hierarchical and no longer allow tasks in
+  intermediate levels, the local state is irrelevant and all
+  statistics represent the state of the entire hierarchy rooted at the
+  given group.
+
 
 5. Planned Changes
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a69ff21c8a9a..4959460fa170 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6283,6 +6283,42 @@ static ssize_t memory_max_write(struct kernfs_open_file *of,
 	return nbytes;
 }
 
+static u64 tree_events(struct mem_cgroup *memcg, int event)
+{
+	struct mem_cgroup *mi;
+	u64 val = 0;
+
+	for_each_mem_cgroup_tree(mi, memcg)
+		val += mem_cgroup_read_events(mi, event);
+	return val;
+}
+
+static int memory_vmstat_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+	struct mem_cgroup *mi;
+	int i;
+
+	for (i = 0; i < NR_LRU_LISTS; i++) {
+		u64 val = 0;
+
+		for_each_mem_cgroup_tree(mi, memcg)
+			val += mem_cgroup_nr_lru_pages(mi, BIT(i));
+		seq_printf(m, "%s %llu\n", vmstat_text[NR_LRU_BASE + i], val);
+	}
+
+	seq_printf(m, "pgalloc %llu\n",
+		   tree_events(memcg, MEM_CGROUP_EVENTS_PGPGIN));
+	seq_printf(m, "pgfree %llu\n",
+		   tree_events(memcg, MEM_CGROUP_EVENTS_PGPGOUT));
+	seq_printf(m, "pgfault %llu\n",
+		   tree_events(memcg, MEM_CGROUP_EVENTS_PGFAULT));
+	seq_printf(m, "pgmajfault %llu\n",
+		   tree_events(memcg, MEM_CGROUP_EVENTS_PGMAJFAULT));
+
+	return 0;
+}
+
 static struct cftype memory_files[] = {
 	{
 		.name = "current",
@@ -6298,6 +6334,10 @@ static struct cftype memory_files[] = {
 		.read_u64 = memory_max_read,
 		.write = memory_max_write,
 	},
+	{
+		.name = "vmstat",
+		.seq_show = memory_vmstat_show,
+	},
 };
 
 struct cgroup_subsys memory_cgrp_subsys = {
-- 
2.0.3

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