On Mon, Jun 08, 2020 at 04:08:17PM -0700, Roman Gushchin wrote:
> 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);
This patch is now in -next and this line causes a warning from clang,
which shows up in every translation unit that includes this header,
which is a lot:
include/linux/memcontrol.h:45:30: warning: implicit conversion from
enumeration type 'enum memcg_stat_item' to different enumeration type
'enum node_stat_item' [-Wenum-conversion]
return vmstat_item_in_bytes(item);
~~~~~~~~~~~~~~~~~~~~ ^~~~
1 warning generated.
I assume this conversion is intentional; if so, it seems like expecting
a specific enum is misleading. Perhaps this should be applied on top?
Cheers,
Nathan
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 2499f78cf32d..bddeb4ce7a4f 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -38,7 +38,7 @@ enum memcg_stat_item {
MEMCG_NR_STAT,
};
-static __always_inline bool memcg_stat_item_in_bytes(enum memcg_stat_item item)
+static __always_inline bool memcg_stat_item_in_bytes(int item)
{
if (item == MEMCG_PERCPU_B)
return true;
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 084ee1c17160..52d7961a24f0 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -211,7 +211,7 @@ enum node_stat_item {
* measured in pages). This defines the API part, the internal representation
* might be different.
*/
-static __always_inline bool vmstat_item_in_bytes(enum node_stat_item item)
+static __always_inline bool vmstat_item_in_bytes(int item)
{
/*
* Global and per-node slab counters track slab pages.
