The patch titled
Subject: mm: deduplicate cacheline padding code
has been added to the -mm mm-unstable branch. Its filename is
mm-deduplicate-cacheline-padding-code.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-deduplicate-cacheline-padding-code.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Shakeel Butt <shakeelb@xxxxxxxxxx>
Subject: mm: deduplicate cacheline padding code
Date: Fri, 26 Aug 2022 23:06:42 +0000
There are three users (mmzone.h, memcontrol.h, page_counter.h) using
similar code for forcing cacheline padding between fields of different
structures. Dedup that code.
Link: https://lkml.kernel.org/r/20220826230642.566725-1-shakeelb@xxxxxxxxxx
Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Suggested-by: Feng Tang <feng.tang@xxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/cache.h | 13 +++++++++++++
include/linux/memcontrol.h | 13 ++-----------
include/linux/mmzone.h | 24 +++++-------------------
include/linux/page_counter.h | 13 ++-----------
4 files changed, 22 insertions(+), 41 deletions(-)
--- a/include/linux/cache.h~mm-deduplicate-cacheline-padding-code
+++ a/include/linux/cache.h
@@ -85,4 +85,17 @@
#define cache_line_size() L1_CACHE_BYTES
#endif
+/*
+ * Helper to add padding within a struct to ensure data fall into separate
+ * cachelines.
+ */
+#if defined(CONFIG_SMP)
+struct cacheline_padding {
+ char x[0];
+} ____cacheline_internodealigned_in_smp;
+#define CACHELINE_PADDING(name) struct cacheline_padding name
+#else
+#define CACHELINE_PADDING(name)
+#endif
+
#endif /* __LINUX_CACHE_H */
--- a/include/linux/memcontrol.h~mm-deduplicate-cacheline-padding-code
+++ a/include/linux/memcontrol.h
@@ -185,15 +185,6 @@ struct mem_cgroup_thresholds {
struct mem_cgroup_threshold_ary *spare;
};
-#if defined(CONFIG_SMP)
-struct memcg_padding {
- char x[0];
-} ____cacheline_internodealigned_in_smp;
-#define MEMCG_PADDING(name) struct memcg_padding name
-#else
-#define MEMCG_PADDING(name)
-#endif
-
/*
* Remember four most recent foreign writebacks with dirty pages in this
* cgroup. Inode sharing is expected to be uncommon and, even if we miss
@@ -304,7 +295,7 @@ struct mem_cgroup {
spinlock_t move_lock;
unsigned long move_lock_flags;
- MEMCG_PADDING(_pad1_);
+ CACHELINE_PADDING(_pad1_);
/* memory.stat */
struct memcg_vmstats vmstats;
@@ -326,7 +317,7 @@ struct mem_cgroup {
struct list_head objcg_list;
#endif
- MEMCG_PADDING(_pad2_);
+ CACHELINE_PADDING(_pad2_);
/*
* set > 0 if pages under this cgroup are moving to other cgroup.
--- a/include/linux/mmzone.h~mm-deduplicate-cacheline-padding-code
+++ a/include/linux/mmzone.h
@@ -121,20 +121,6 @@ static inline bool free_area_empty(struc
struct pglist_data;
-/*
- * Add a wild amount of padding here to ensure data fall into separate
- * cachelines. There are very few zone structures in the machine, so space
- * consumption is not a concern here.
- */
-#if defined(CONFIG_SMP)
-struct zone_padding {
- char x[0];
-} ____cacheline_internodealigned_in_smp;
-#define ZONE_PADDING(name) struct zone_padding name;
-#else
-#define ZONE_PADDING(name)
-#endif
-
#ifdef CONFIG_NUMA
enum numa_stat_item {
NUMA_HIT, /* allocated in intended node */
@@ -837,7 +823,7 @@ struct zone {
int initialized;
/* Write-intensive fields used from the page allocator */
- ZONE_PADDING(_pad1_)
+ CACHELINE_PADDING(_pad1_);
/* free areas of different sizes */
struct free_area free_area[MAX_ORDER];
@@ -849,7 +835,7 @@ struct zone {
spinlock_t lock;
/* Write-intensive fields used by compaction and vmstats. */
- ZONE_PADDING(_pad2_)
+ CACHELINE_PADDING(_pad2_);
/*
* When free pages are below this point, additional steps are taken
@@ -886,7 +872,7 @@ struct zone {
bool contiguous;
- ZONE_PADDING(_pad3_)
+ CACHELINE_PADDING(_pad3_);
/* Zone statistics */
atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS];
atomic_long_t vm_numa_event[NR_VM_NUMA_EVENT_ITEMS];
@@ -1194,7 +1180,7 @@ typedef struct pglist_data {
#endif /* CONFIG_NUMA */
/* Write-intensive fields used by page reclaim */
- ZONE_PADDING(_pad1_)
+ CACHELINE_PADDING(_pad1_);
#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
/*
@@ -1239,7 +1225,7 @@ typedef struct pglist_data {
struct lru_gen_mm_walk mm_walk;
#endif
- ZONE_PADDING(_pad2_)
+ CACHELINE_PADDING(_pad2_);
/* Per-node vmstats */
struct per_cpu_nodestat __percpu *per_cpu_nodestats;
--- a/include/linux/page_counter.h~mm-deduplicate-cacheline-padding-code
+++ a/include/linux/page_counter.h
@@ -7,22 +7,13 @@
#include <linux/kernel.h>
#include <asm/page.h>
-#if defined(CONFIG_SMP)
-struct pc_padding {
- char x[0];
-} ____cacheline_internodealigned_in_smp;
-#define PC_PADDING(name) struct pc_padding name
-#else
-#define PC_PADDING(name)
-#endif
-
struct page_counter {
/*
* Make sure 'usage' does not share cacheline with any other field. The
* memcg->memory.usage is a hot member of struct mem_cgroup.
*/
atomic_long_t usage;
- PC_PADDING(_pad1_);
+ CACHELINE_PADDING(_pad1_);
/* effective memory.min and memory.min usage tracking */
unsigned long emin;
@@ -38,7 +29,7 @@ struct page_counter {
unsigned long failcnt;
/* Keep all the read most fields in a separete cacheline. */
- PC_PADDING(_pad2_);
+ CACHELINE_PADDING(_pad2_);
unsigned long min;
unsigned long low;
_
Patches currently in -mm which might be from shakeelb@xxxxxxxxxx are
revert-memcg-cleanup-racy-sum-avoidance-code.patch
mm-page_counter-remove-unneeded-atomic-ops-for-low-min.patch
mm-page_counter-rearrange-struct-page_counter-fields.patch
memcg-increase-memcg_charge_batch-to-64.patch
mm-deduplicate-cacheline-padding-code.patch
