Currently the madvise_cold_or_pageout_pte_range() function exhibits
significant latency under memory pressure, which can be effectively
reduced by adding cond_resched() within the loop.
When the batch_count reaches SWAP_CLUSTER_MAX, we reschedule
the task to ensure fairness and avoid long lock holding times.
Signed-off-by: Jiexun Wang <wangjiexun@xxxxxxxxxxx>
---
mm/madvise.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/mm/madvise.c b/mm/madvise.c
index 4dded5d27e7e..df760096ea85 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -31,6 +31,7 @@
#include <linux/swapops.h>
#include <linux/shmem_fs.h>
#include <linux/mmu_notifier.h>
+#include <linux/swap.h>
#include <asm/tlb.h>
@@ -353,6 +354,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
struct folio *folio = NULL;
LIST_HEAD(folio_list);
bool pageout_anon_only_filter;
+ unsigned int batch_count = 0;
if (fatal_signal_pending(current))
return -EINTR;
@@ -441,6 +443,13 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
arch_enter_lazy_mmu_mode();
for (; addr < end; pte++, addr += PAGE_SIZE) {
ptent = ptep_get(pte);
+
+ if (++batch_count == SWAP_CLUSTER_MAX) {
+ pte_unmap_unlock(start_pte, ptl);
+ cond_resched();
+ start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+ batch_count = 0;
+ }
if (pte_none(ptent))
continue;
--
2.34.1
