Percpu memory can represent a noticeable chunk of the total
memory consumption, especially on big machines with many CPUs.
Let's track percpu memory usage for each memcg and display
it in memory.stat.
A percpu allocation is usually scattered over multiple pages
(and nodes), and can be significantly smaller than a page.
So let's add a byte-sized counter on the memcg level:
MEMCG_PERCPU_B. Byte-sized vmstat infra created for slabs
can be perfectly reused for percpu case.
Signed-off-by: Roman Gushchin <guro@xxxxxx>
Acked-by: Dennis Zhou <dennis@xxxxxxxxxx>
---
Documentation/admin-guide/cgroup-v2.rst | 4 ++++
include/linux/memcontrol.h | 8 ++++++++
mm/memcontrol.c | 4 +++-
mm/percpu.c | 10 ++++++++++
4 files changed, 25 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index ce3e05e41724..7c1e784239bf 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -1274,6 +1274,10 @@ PAGE_SIZE multiple when read back.
Amount of memory used for storing in-kernel data
structures.
+ percpu
+ Amount of memory used for storing per-cpu kernel
+ data structures.
+
sock
Amount of memory used in network transmission buffers
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index eede46c43573..7ed3af71a6fb 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -32,11 +32,19 @@ struct kmem_cache;
enum memcg_stat_item {
MEMCG_SWAP = NR_VM_NODE_STAT_ITEMS,
MEMCG_SOCK,
+ MEMCG_PERCPU_B,
/* XXX: why are these zone and not node counters? */
MEMCG_KERNEL_STACK_KB,
MEMCG_NR_STAT,
};
+static __always_inline bool memcg_stat_item_in_bytes(enum memcg_stat_item item)
+{
+ if (item == MEMCG_PERCPU_B)
+ return true;
+ return vmstat_item_in_bytes(item);
+}
+
enum memcg_memory_event {
MEMCG_LOW,
MEMCG_HIGH,
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 93b2e73ef2f7..839b4d890a90 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -783,7 +783,7 @@ void __mod_memcg_state(struct mem_cgroup *memcg, int idx, int val)
if (mem_cgroup_disabled())
return;
- if (vmstat_item_in_bytes(idx))
+ if (memcg_stat_item_in_bytes(idx))
threshold <<= PAGE_SHIFT;
x = val + __this_cpu_read(memcg->vmstats_percpu->stat[idx]);
@@ -1490,6 +1490,8 @@ static char *memory_stat_format(struct mem_cgroup *memcg)
seq_buf_printf(&s, "slab %llu\n",
(u64)(memcg_page_state(memcg, NR_SLAB_RECLAIMABLE_B) +
memcg_page_state(memcg, NR_SLAB_UNRECLAIMABLE_B)));
+ seq_buf_printf(&s, "percpu %llu\n",
+ (u64)memcg_page_state(memcg, MEMCG_PERCPU_B));
seq_buf_printf(&s, "sock %llu\n",
(u64)memcg_page_state(memcg, MEMCG_SOCK) *
PAGE_SIZE);
diff --git a/mm/percpu.c b/mm/percpu.c
index 8ebd9fe30430..18d3d049bf91 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1608,6 +1608,11 @@ static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
if (chunk) {
chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = objcg;
+
+ rcu_read_lock();
+ mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
+ size * num_possible_cpus());
+ rcu_read_unlock();
} else {
obj_cgroup_uncharge(objcg, size * num_possible_cpus());
obj_cgroup_put(objcg);
@@ -1626,6 +1631,11 @@ static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
obj_cgroup_uncharge(objcg, size * num_possible_cpus());
+ rcu_read_lock();
+ mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
+ -(size * num_possible_cpus()));
+ rcu_read_unlock();
+
obj_cgroup_put(objcg);
}
--
2.25.4
