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mm, swap: remove fragment clusters counter

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It was used for calculating the iteration number when the swap allocator
wants to scan the whole fragment list.  Now the allocator only scans one
fragment cluster at a time, so no one uses this counter anymore.

Remove it as a cleanup; the performance change is marginal:

Build linux kernel using 10G ZRAM, make -j96, defconfig with 2G cgroup
memory limit, on top of tmpfs, 64kB mTHP enabled:

Before:  sys time: 6278.45s
After:   sys time: 6176.34s

Change to 8G ZRAM:

Before:  sys time: 5572.85s
After:   sys time: 5531.49s

Link: https://lkml.kernel.org/r/20250806161748.76651-3-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Kairui Song 2025-08-07 00:17:47 +08:00 committed by Andrew Morton
parent b25786b4a9
commit 913fff3145
2 changed files with 0 additions and 8 deletions
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1
include/linux/swap.h
View File

@ -310,7 +310,6 @@ struct swap_info_struct {
/* list of cluster that contains at least one free slot */
struct list_head frag_clusters[SWAP_NR_ORDERS];
/* list of cluster that are fragmented or contented */
atomic_long_t frag_cluster_nr[SWAP_NR_ORDERS];
unsigned int pages; /* total of usable pages of swap */
atomic_long_t inuse_pages; /* number of those currently in use */
struct swap_sequential_cluster *global_cluster; /* Use one global cluster for rotating device */

7
mm/swapfile.c
View File

@ -470,11 +470,6 @@ static void move_cluster(struct swap_info_struct *si,
else
list_move_tail(&ci->list, list);
spin_unlock(&si->lock);
if (ci->flags == CLUSTER_FLAG_FRAG)
atomic_long_dec(&si->frag_cluster_nr[ci->order]);
else if (new_flags == CLUSTER_FLAG_FRAG)
atomic_long_inc(&si->frag_cluster_nr[ci->order]);
ci->flags = new_flags;
}
@ -965,7 +960,6 @@ new_cluster:
* allocation, but reclaim may drop si->lock and race with another user.
*/
while ((ci = isolate_lock_cluster(si, &si->frag_clusters[o]))) {
atomic_long_dec(&si->frag_cluster_nr[o]);
found = alloc_swap_scan_cluster(si, ci, cluster_offset(si, ci),
0, usage);
if (found)
@ -3217,7 +3211,6 @@ static struct swap_cluster_info *setup_clusters(struct swap_info_struct *si,
for (i = 0; i < SWAP_NR_ORDERS; i++) {
INIT_LIST_HEAD(&si->nonfull_clusters[i]);
INIT_LIST_HEAD(&si->frag_clusters[i]);
atomic_long_set(&si->frag_cluster_nr[i], 0);
}
/*