The patch titled
Subject: mm/swapfile.c: optimize code in setup_clusters()
has been added to the -mm mm-unstable branch. Its filename is
mm-swapfilec-optimize-code-in-setup_clusters.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-swapfilec-optimize-code-in-setup_clusters.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: Baoquan He <bhe@xxxxxxxxxx>
Subject: mm/swapfile.c: optimize code in setup_clusters()
Date: Wed, 5 Feb 2025 17:27:16 +0800
In the last 'for' loop inside setup_clusters(), using two local variable
'k' and 'j' are obvisouly redundant. Using 'j' is enough and simpler.
And also move macro SWAP_CLUSTER_COLS close to its only user
setup_clusters().
Link: https://lkml.kernel.org/r/20250205092721.9395-8-bhe@xxxxxxxxxx
Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
Cc: Chis Li <chrisl@xxxxxxxxxx>
Cc: Kairui Song <ryncsn@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/swapfile.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)
--- a/mm/swapfile.c~mm-swapfilec-optimize-code-in-setup_clusters
+++ a/mm/swapfile.c
@@ -3123,13 +3123,6 @@ static unsigned long read_swap_header(st
return maxpages;
}
-#define SWAP_CLUSTER_INFO_COLS \
- DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info))
-#define SWAP_CLUSTER_SPACE_COLS \
- DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER)
-#define SWAP_CLUSTER_COLS \
- max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS)
-
static int setup_swap_map_and_extents(struct swap_info_struct *si,
union swap_header *swap_header,
unsigned char *swap_map,
@@ -3169,13 +3162,20 @@ static int setup_swap_map_and_extents(st
return nr_extents;
}
+#define SWAP_CLUSTER_INFO_COLS \
+ DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info))
+#define SWAP_CLUSTER_SPACE_COLS \
+ DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER)
+#define SWAP_CLUSTER_COLS \
+ max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS)
+
static struct swap_cluster_info *setup_clusters(struct swap_info_struct *si,
union swap_header *swap_header,
unsigned long maxpages)
{
unsigned long nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER);
struct swap_cluster_info *cluster_info;
- unsigned long i, j, k, idx;
+ unsigned long i, j, idx;
int cpu, err = -ENOMEM;
cluster_info = kvcalloc(nr_clusters, sizeof(*cluster_info), GFP_KERNEL);
@@ -3236,8 +3236,7 @@ static struct swap_cluster_info *setup_c
* Reduce false cache line sharing between cluster_info and
* sharing same address space.
*/
- for (k = 0; k < SWAP_CLUSTER_COLS; k++) {
- j = k % SWAP_CLUSTER_COLS;
+ for (j = 0; j < SWAP_CLUSTER_COLS; j++) {
for (i = 0; i < DIV_ROUND_UP(nr_clusters, SWAP_CLUSTER_COLS); i++) {
struct swap_cluster_info *ci;
idx = i * SWAP_CLUSTER_COLS + j;
_
Patches currently in -mm which might be from bhe@xxxxxxxxxx are
mm-swap_statec-fix-the-obsolete-code-comment.patch
mm-swap_statec-optimize-the-code-in-clear_shadow_from_swap_cache.patch
mm-swap-remove-swap_flag_prio_shift.patch
mm-swap-skip-scanning-cluster-range-if-its-empty-cluster.patch
mm-swap-rename-swap_is_has_cache-to-swap_only_has_cache.patch
mm-swapfilec-update-the-code-comment-above-swap_count_continued.patch
mm-swapfilec-optimize-code-in-setup_clusters.patch
mm-swap_statec-remove-the-meaningless-code-comment.patch
mm-swapfilec-remove-the-unneeded-checking.patch
mm-swap-rename-swap_swapcount-to-swap_entry_swapped.patch
mm-swapfilec-remove-the-incorrect-code-comment.patch
mm-swapfilec-open-code-cluster_alloc_swap.patch
