[PATCH v2 01/13] mm, swap: minor clean up for swap entry allocation

Kairui Song
2024-12-24T14:39:36Z

Direct reclaim can skip the whole folio after reclaimed a set of
folio based slots. Also simplify the code for allocation, reduce
indention.

Signed-off-by: Kairui Song <kasong@tencent.com>
---
mm/swapfile.c | 59 +++++++++++++++++++++++++--------------------------
1 file changed, 29 insertions(+), 30 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index b0a9071cfe1d..f8002f110104 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -604,23 +604,28 @@ static bool cluster_reclaim_range(struct swap_info_struct *si,
unsigned long start, unsigned long end)
{
unsigned char *map = si->swap_map;
- unsigned long offset;
+ unsigned long offset = start;
+ int nr_reclaim;

spin_unlock(&ci->lock);
spin_unlock(&si->lock);

- for (offset = start; offset < end; offset++) {
+ do {
switch (READ_ONCE(map[offset])) {
case 0:
- continue;
+ offset++;
+ break;
case SWAP_HAS_CACHE:
- if (__try_to_reclaim_swap(si, offset, TTRS_ANYWAY | TTRS_DIRECT) > 0)
- continue;
- goto out;
+ nr_reclaim = __try_to_reclaim_swap(si, offset, TTRS_ANYWAY | TTRS_DIRECT);
+ if (nr_reclaim > 0)
+ offset += nr_reclaim;
+ else
+ goto out;
+ break;
default:
goto out;
}
- }
+ } while (offset < end);
out:
spin_lock(&si->lock);
spin_lock(&ci->lock);
@@ -838,35 +843,30 @@ static unsigned long cluster_alloc_swap_entry(struct swap_info_struct *si, int o
&found, order, usage);
frags++;
if (found)
- break;
+ goto done;
}

- if (!found) {
+ /*
+ * Nonfull clusters are moved to frag tail if we reached
+ * here, count them too, don't over scan the frag list.
+ */
+ while (frags < si->frag_cluster_nr[order]) {
+ ci = list_first_entry(&si->frag_clusters[order],
+ struct swap_cluster_info, list);
/*
- * Nonfull clusters are moved to frag tail if we reached
- * here, count them too, don't over scan the frag list.
+ * Rotate the frag list to iterate, they were all failing
+ * high order allocation or moved here due to per-CPU usage,
+ * this help keeping usable cluster ahead.
*/
- while (frags < si->frag_cluster_nr[order]) {
- ci = list_first_entry(&si->frag_clusters[order],
- struct swap_cluster_info, list);
- /*
- * Rotate the frag list to iterate, they were all failing
- * high order allocation or moved here due to per-CPU usage,
- * this help keeping usable cluster ahead.
- */
- list_move_tail(&ci->list, &si->frag_clusters[order]);
- offset = alloc_swap_scan_cluster(si, cluster_offset(si, ci),
- &found, order, usage);
- frags++;
- if (found)
- break;
- }
+ list_move_tail(&ci->list, &si->frag_clusters[order]);
+ offset = alloc_swap_scan_cluster(si, cluster_offset(si, ci),
+ &found, order, usage);
+ frags++;
+ if (found)
+ goto done;
}
}

- if (found)
- goto done;
-
if (!list_empty(&si->discard_clusters)) {
/*
* we don't have free cluster but have some clusters in
@@ -904,7 +904,6 @@ static unsigned long cluster_alloc_swap_entry(struct swap_info_struct *si, int o
goto done;
}
}
-
done:
cluster->next[order] = offset;
return found;
--
2.47.1