Commit 772616b0 authored by Roman Gushchin's avatar Roman Gushchin Committed by Linus Torvalds
Browse files

mm: memcg/percpu: per-memcg percpu memory statistics 

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.

[guro@fb.com: v3]
  Link: http://lkml.kernel.org/r/20200623184515.4132564-4-guro@fb.com



Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
Acked-by: default avatarDennis Zhou <dennis@kernel.org>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Tobin C. Harding <tobin@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Waiman Long <longman@redhat.com>
Cc: Bixuan Cui <cuibixuan@huawei.com>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: http://lkml.kernel.org/r/20200608230819.832349-4-guro@fb.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3c7be18a

Documentation/admin-guide/cgroup-v2.rst

+4 −0
Original line number Diff line number Diff line
@@ -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

include/linux/memcontrol.h

+8 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ struct kmem_cache; 
enum memcg_stat_item {

	MEMCG_SWAP = NR_VM_NODE_STAT_ITEMS,

	MEMCG_SOCK,

	MEMCG_PERCPU_B,

	MEMCG_NR_STAT,

};
@@ -339,6 +340,13 @@ struct mem_cgroup { 


extern struct mem_cgroup *root_mem_cgroup;



static __always_inline bool memcg_stat_item_in_bytes(int idx)

{

	if (idx == MEMCG_PERCPU_B)

		return true;

	return vmstat_item_in_bytes(idx);

}



static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)

{

	return (memcg == root_mem_cgroup);

mm/memcontrol.c

+3 −1
Original line number Diff line number Diff line
@@ -781,7 +781,7 @@ 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]);
@@ -1488,6 +1488,8 @@ 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);

mm/percpu.c

+10 −0
Original line number Diff line number Diff line
@@ -1610,6 +1610,11 @@ 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);
@@ -1628,6 +1633,11 @@ 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);

}

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