The new BPF capability enables finer-grained THP policy decisions by
introducing separate handling for swap faults versus normal page faults.
As highlighted by Barry:
We’ve observed that swapping in large folios can lead to more
swap thrashing for some workloads- e.g. kernel build. Consequently,
some workloads might prefer swapping in smaller folios than those
allocated by alloc_anon_folio().
While prtcl() could potentially be extended to leverage this new policy,
doing so would require modifications to the uAPI.
Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
Cc: Barry Song <21cnbao@xxxxxxxxx>
---
include/linux/huge_mm.h | 3 ++-
mm/huge_memory.c | 2 +-
mm/memory.c | 2 +-
3 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index f72a5fd04e4f..b9742453806f 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -97,9 +97,10 @@ extern struct kobj_attribute thpsize_shmem_enabled_attr;
enum tva_type {
TVA_SMAPS, /* Exposing "THPeligible:" in smaps. */
- TVA_PAGEFAULT, /* Serving a page fault. */
+ TVA_PAGEFAULT, /* Serving a non-swap page fault. */
TVA_KHUGEPAGED, /* Khugepaged collapse. */
TVA_FORCED_COLLAPSE, /* Forced collapse (e.g. MADV_COLLAPSE). */
+ TVA_SWAP, /* Serving a swap */
};
#define thp_vma_allowable_order(vma, vm_flags, type, order) \
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 26cedfcd7418..523153d21a41 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -103,7 +103,7 @@ unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
unsigned long orders)
{
const bool smaps = type == TVA_SMAPS;
- const bool in_pf = type == TVA_PAGEFAULT;
+ const bool in_pf = (type == TVA_PAGEFAULT || type == TVA_SWAP);
const bool forced_collapse = type == TVA_FORCED_COLLAPSE;
unsigned long supported_orders;
diff --git a/mm/memory.c b/mm/memory.c
index d9de6c056179..d8819cac7930 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4515,7 +4515,7 @@ static struct folio *alloc_swap_folio(struct vm_fault *vmf)
* Get a list of all the (large) orders below PMD_ORDER that are enabled
* and suitable for swapping THP.
*/
- orders = thp_vma_allowable_orders(vma, vma->vm_flags, TVA_PAGEFAULT,
+ orders = thp_vma_allowable_orders(vma, vma->vm_flags, TVA_SWAP,
BIT(PMD_ORDER) - 1);
orders = thp_vma_suitable_orders(vma, vmf->address, orders);
orders = thp_swap_suitable_orders(swp_offset(entry),
--
2.47.3
