From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
The vma_munmap_struct has a hole of 4 bytes and pushes the struct to
three cachelines. Relocating the three booleans upwards allows for the
struct to only use two cachelines (as reported by pahole on amd64).
Before:
struct vma_munmap_struct {
struct vma_iterator * vmi; /* 0 8 */
struct vm_area_struct * vma; /* 8 8 */
struct vm_area_struct * prev; /* 16 8 */
struct vm_area_struct * next; /* 24 8 */
struct list_head * uf; /* 32 8 */
long unsigned int start; /* 40 8 */
long unsigned int end; /* 48 8 */
long unsigned int unmap_start; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
long unsigned int unmap_end; /* 64 8 */
int vma_count; /* 72 4 */
/* XXX 4 bytes hole, try to pack */
long unsigned int nr_pages; /* 80 8 */
long unsigned int locked_vm; /* 88 8 */
long unsigned int nr_accounted; /* 96 8 */
long unsigned int exec_vm; /* 104 8 */
long unsigned int stack_vm; /* 112 8 */
long unsigned int data_vm; /* 120 8 */
/* --- cacheline 2 boundary (128 bytes) --- */
bool unlock; /* 128 1 */
bool clear_ptes; /* 129 1 */
bool closed_vm_ops; /* 130 1 */
/* size: 136, cachelines: 3, members: 19 */
/* sum members: 127, holes: 1, sum holes: 4 */
/* padding: 5 */
/* last cacheline: 8 bytes */
};
After:
struct vma_munmap_struct {
struct vma_iterator * vmi; /* 0 8 */
struct vm_area_struct * vma; /* 8 8 */
struct vm_area_struct * prev; /* 16 8 */
struct vm_area_struct * next; /* 24 8 */
struct list_head * uf; /* 32 8 */
long unsigned int start; /* 40 8 */
long unsigned int end; /* 48 8 */
long unsigned int unmap_start; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
long unsigned int unmap_end; /* 64 8 */
int vma_count; /* 72 4 */
bool unlock; /* 76 1 */
bool clear_ptes; /* 77 1 */
bool closed_vm_ops; /* 78 1 */
/* XXX 1 byte hole, try to pack */
long unsigned int nr_pages; /* 80 8 */
long unsigned int locked_vm; /* 88 8 */
long unsigned int nr_accounted; /* 96 8 */
long unsigned int exec_vm; /* 104 8 */
long unsigned int stack_vm; /* 112 8 */
long unsigned int data_vm; /* 120 8 */
/* size: 128, cachelines: 2, members: 19 */
/* sum members: 127, holes: 1, sum holes: 1 */
};
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
---
mm/vma.h | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/mm/vma.h b/mm/vma.h
index 6900e95bcaac..85616faa4490 100644
--- a/mm/vma.h
+++ b/mm/vma.h
@@ -40,15 +40,16 @@ struct vma_munmap_struct {
unsigned long unmap_start; /* Unmap PTE start */
unsigned long unmap_end; /* Unmap PTE end */
int vma_count; /* Number of vmas that will be removed */
+ bool unlock; /* Unlock after the munmap */
+ bool clear_ptes; /* If there are outstanding PTE to be cleared */
+ bool closed_vm_ops; /* call_mmap() was encountered, so vmas may be closed */
+ /* 1 byte hole */
unsigned long nr_pages; /* Number of pages being removed */
unsigned long locked_vm; /* Number of locked pages */
unsigned long nr_accounted; /* Number of VM_ACCOUNT pages */
unsigned long exec_vm;
unsigned long stack_vm;
unsigned long data_vm;
- bool unlock; /* Unlock after the munmap */
- bool clear_ptes; /* If there are outstanding PTE to be cleared */
- bool closed_vm_ops; /* call_mmap() was encountered, so vmas may be closed */
};
#ifdef CONFIG_DEBUG_VM_MAPLE_TREE
--
2.43.0
