From: Shakeel Butt <shakeel.butt@linux.dev>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Muchun Song <muchun.song@linux.dev>,
Usama Arif <usama.arif@linux.dev>,
Meta kernel team <kernel-team@meta.com>,
cgroups@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 4/6] memcg: group the cold fields of struct mem_cgroup
Date: Fri, 4 Sep 2026 20:05:20 -0700 [thread overview]
Message-ID: <20260905030522.1887837-5-shakeel.butt@linux.dev> (raw)
In-Reply-To: <20260905030522.1887837-1-shakeel.butt@linux.dev>
These fields are only touched by the cgroup control paths:
memory_peaks, swap_peaks, peaks_lock memory.peak open/read/release
events_file, events_local_file,
swap_events_file cgroup_file_notify()
cgwb_list, cgwb_domain, cgwb_frn writeback setup and the
foreign dirty slow path
mm_list MGLRU mm list
They sit in the middle of the struct today. The three cgroup_file
members alone are 192 bytes of notify state next to the vmstats
pointer. Put them in one cache line group.
No functional change.
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
---
include/linux/memcontrol.h | 49 ++++++++++++++++++++++----------------
mm/memcontrol.c | 25 +++++++++++++++++++
2 files changed, 53 insertions(+), 21 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 32b77ec5ba98..635929a1f13b 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -228,11 +228,37 @@ struct mem_cgroup {
__cacheline_group_end_aligned(memcg_write_hot);
+ /*
+ * Off the charge and fault paths. Not write free: cgwb_domain is
+ * written on every writeout completion and mm_list on fork, exit and
+ * MGLRU aging. They are grouped here so those writes cannot land on
+ * a line that the fast paths read.
+ */
+ __cacheline_group_begin_aligned(memcg_cold);
/* registered local peak watchers */
struct list_head memory_peaks;
struct list_head swap_peaks;
spinlock_t peaks_lock;
+ /* memory.events and memory.events.local */
+ struct cgroup_file events_file;
+ struct cgroup_file events_local_file;
+
+ /* handle for "memory.swap.events" */
+ struct cgroup_file swap_events_file;
+
+#ifdef CONFIG_CGROUP_WRITEBACK
+ struct list_head cgwb_list;
+ struct wb_domain cgwb_domain;
+ struct memcg_cgwb_frn cgwb_frn[MEMCG_CGWB_FRN_CNT];
+#endif
+
+#ifdef CONFIG_LRU_GEN_WALKS_MMU
+ /* per-memcg mm_struct list */
+ struct lru_gen_mm_list mm_list;
+#endif
+ __cacheline_group_end_aligned(memcg_cold);
+
#ifdef CONFIG_ZSWAP
unsigned long zswap_max;
@@ -248,37 +274,18 @@ struct mem_cgroup {
*/
bool oom_group;
- /* memory.events and memory.events.local */
- struct cgroup_file events_file;
- struct cgroup_file events_local_file;
-
- /* handle for "memory.swap.events" */
- struct cgroup_file swap_events_file;
-
/* memory.stat */
struct memcg_vmstats *vmstats;
int kmemcg_id;
-#ifdef CONFIG_CGROUP_WRITEBACK
- struct list_head cgwb_list;
-#endif
-
/* Keep the hot per-CPU stats pointer away from memory event counters. */
struct memcg_vmstats_percpu __percpu *vmstats_percpu
____cacheline_aligned_in_smp;
-#ifdef CONFIG_CGROUP_WRITEBACK
- struct wb_domain cgwb_domain;
- struct memcg_cgwb_frn cgwb_frn[MEMCG_CGWB_FRN_CNT];
-#endif
-
-#ifdef CONFIG_LRU_GEN_WALKS_MMU
- /* per-memcg mm_struct list */
- struct lru_gen_mm_list mm_list;
-#endif
-
#ifdef CONFIG_MEMCG_V1
+ /* v1 only. Not grouped: v1 is legacy, sorting it is not worth it. */
+
/* Legacy consumer-oriented counters */
struct page_counter kmem; /* v1 only */
struct page_counter tcpmem; /* v1 only */
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2e209dedeb4f..b2cc82c936ed 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5754,6 +5754,31 @@ static void __init memcg_struct_check(void)
high_irq_work);
CACHELINE_ASSERT_GROUP_MEMBER(struct mem_cgroup, memcg_write_hot,
high_work);
+
+ CACHELINE_ASSERT_GROUP_MEMBER(struct mem_cgroup, memcg_cold,
+ memory_peaks);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct mem_cgroup, memcg_cold,
+ swap_peaks);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct mem_cgroup, memcg_cold,
+ peaks_lock);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct mem_cgroup, memcg_cold,
+ events_file);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct mem_cgroup, memcg_cold,
+ events_local_file);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct mem_cgroup, memcg_cold,
+ swap_events_file);
+#ifdef CONFIG_CGROUP_WRITEBACK
+ CACHELINE_ASSERT_GROUP_MEMBER(struct mem_cgroup, memcg_cold,
+ cgwb_list);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct mem_cgroup, memcg_cold,
+ cgwb_domain);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct mem_cgroup, memcg_cold,
+ cgwb_frn);
+#endif
+#ifdef CONFIG_LRU_GEN_WALKS_MMU
+ CACHELINE_ASSERT_GROUP_MEMBER(struct mem_cgroup, memcg_cold,
+ mm_list);
+#endif
}
int __init mem_cgroup_init(void)
--
2.53.0-Meta
next prev parent reply other threads:[~2026-09-05 3:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-05 3:05 [PATCH 0/6] memcg: group struct fields by access pattern Shakeel Butt
2026-09-05 3:05 ` [PATCH 1/6] memcg: move per-node objcg to the read-mostly fields Shakeel Butt
2026-09-05 3:05 ` [PATCH 2/6] memcg: split mem_cgroup_private_id into two fields Shakeel Butt
2026-09-05 3:05 ` [PATCH 3/6] memcg: group the write-hot fields of struct mem_cgroup Shakeel Butt
2026-09-05 3:05 ` Shakeel Butt [this message]
2026-09-05 3:05 ` [PATCH 5/6] memcg: group the read-mostly " Shakeel Butt
2026-09-05 3:05 ` [PATCH 6/6] memcg: group the fields of struct mem_cgroup_per_node Shakeel Butt
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