Iterate over a folio_batch rather than a linked list. This is easier for
the CPU to prefetch and has a batch count naturally built in so we don't
need to track it. Again, this lowers the maximum lock hold time from
32 folios to 15, but I do not expect this to have a significant effect.
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
mm/internal.h | 5 +++--
mm/page_alloc.c | 59 ++++++++++++++++++++++++++++++-------------------
2 files changed, 39 insertions(+), 25 deletions(-)
diff --git a/mm/internal.h b/mm/internal.h
index d6044c684e93..4d45b351e0fd 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -449,8 +449,9 @@ extern void post_alloc_hook(struct page *page, unsigned int order,
gfp_t gfp_flags);
extern int user_min_free_kbytes;
-extern void free_unref_page(struct page *page, unsigned int order);
-extern void free_unref_page_list(struct list_head *list);
+void free_unref_page(struct page *page, unsigned int order);
+void free_unref_folios(struct folio_batch *fbatch);
+void free_unref_page_list(struct list_head *list);
extern void zone_pcp_reset(struct zone *zone);
extern void zone_pcp_disable(struct zone *zone);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a8292c7a0391..8ef1c5c86472 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -32,6 +32,7 @@
#include <linux/sysctl.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
+#include <linux/pagevec.h>
#include <linux/memory_hotplug.h>
#include <linux/nodemask.h>
#include <linux/vmstat.h>
@@ -2551,57 +2552,51 @@ void free_unref_page(struct page *page, unsigned int order)
}
/*
- * Free a list of 0-order pages
+ * Free a batch of 0-order pages
*/
-void free_unref_page_list(struct list_head *list)
+void free_unref_folios(struct folio_batch *folios)
{
unsigned long __maybe_unused UP_flags;
- struct folio *folio, *next;
struct per_cpu_pages *pcp = NULL;
struct zone *locked_zone = NULL;
- int batch_count = 0;
- int migratetype;
+ int i, j, migratetype;
- /* Prepare pages for freeing */
- list_for_each_entry_safe(folio, next, list, lru) {
+ /* Prepare folios for freeing */
+ for (i = 0, j = 0; i < folios->nr; i++) {
+ struct folio *folio = folios->folios[i];
unsigned long pfn = folio_pfn(folio);
- if (!free_unref_page_prepare(&folio->page, pfn, 0)) {
- list_del(&folio->lru);
+ if (!free_unref_page_prepare(&folio->page, pfn, 0))
continue;
- }
/*
- * Free isolated pages directly to the allocator, see
+ * Free isolated folios directly to the allocator, see
* comment in free_unref_page.
*/
migratetype = get_pcppage_migratetype(&folio->page);
if (unlikely(is_migrate_isolate(migratetype))) {
- list_del(&folio->lru);
free_one_page(folio_zone(folio), &folio->page, pfn,
0, migratetype, FPI_NONE);
continue;
}
+ if (j != i)
+ folios->folios[j] = folio;
+ j++;
}
+ folios->nr = j;
- list_for_each_entry_safe(folio, next, list, lru) {
+ for (i = 0; i < folios->nr; i++) {
+ struct folio *folio = folios->folios[i];
struct zone *zone = folio_zone(folio);
- list_del(&folio->lru);
migratetype = get_pcppage_migratetype(&folio->page);
- /*
- * Either different zone requiring a different pcp lock or
- * excessive lock hold times when freeing a large list of
- * folios.
- */
- if (zone != locked_zone || batch_count == SWAP_CLUSTER_MAX) {
+ /* Different zone requires a different pcp lock */
+ if (zone != locked_zone) {
if (pcp) {
pcp_spin_unlock(pcp);
pcp_trylock_finish(UP_flags);
}
- batch_count = 0;
-
/*
* trylock is necessary as folios may be getting freed
* from IRQ or SoftIRQ context after an IO completion.
@@ -2628,13 +2623,31 @@ void free_unref_page_list(struct list_head *list)
trace_mm_page_free_batched(&folio->page);
free_unref_page_commit(zone, pcp, &folio->page, migratetype, 0);
- batch_count++;
}
if (pcp) {
pcp_spin_unlock(pcp);
pcp_trylock_finish(UP_flags);
}
+ folios->nr = 0;
+}
+
+void free_unref_page_list(struct list_head *list)
+{
+ struct folio_batch fbatch;
+
+ folio_batch_init(&fbatch);
+ while (!list_empty(list)) {
+ struct folio *folio = list_first_entry(list, struct folio, lru);
+
+ list_del(&folio->lru);
+ if (folio_batch_add(&fbatch, folio) > 0)
+ continue;
+ free_unref_folios(&fbatch);
+ }
+
+ if (fbatch.nr)
+ free_unref_folios(&fbatch);
}
/*
--
2.43.0
