[PATCH v2 3/5] mm/memcontrol: Reorder memcg_stock_pcp members to avoid holes
From: Leonardo Bras
Date: Wed Jan 25 2023 - 02:37:05 EST
In 64-bit architectures, the current layout of memcg_stock_pcp should look
like this:
struct memcg_stock_pcp {
spinlock_t stock_lock; /* 0 4 */
/* 4 bytes hole */
struct mem_cgroup * cached; /* 8 8 */
unsigned int nr_pages; /* 16 4 */
/* 4 bytes hole */
[...]
};
This happens because pointers will have 8 bytes (64-bit) and ints will have
4 bytes.
Those 2 holes are avoided if we reorder nr_pages and cached,
effectivelly putting nr_pages in the first hole, and saving 8 bytes.
Signed-off-by: Leonardo Bras <leobras@xxxxxxxxxx>
---
mm/memcontrol.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 1d5c108413c83..373fa78c4d881 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2173,8 +2173,8 @@ void unlock_page_memcg(struct page *page)
struct memcg_stock_pcp {
spinlock_t stock_lock; /* Protects the percpu struct */
- struct mem_cgroup *cached; /* this never be root cgroup */
unsigned int nr_pages;
+ struct mem_cgroup *cached; /* this never be root cgroup */
#ifdef CONFIG_MEMCG_KMEM
struct obj_cgroup *cached_objcg;
--
2.39.1