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Subject[PATCH -mm v2 01/11] pagewalk: remove pgd_entry() and pud_entry()
Date
Currently no user of page table walker sets ->pgd_entry() or ->pud_entry(),
so checking their existence in each loop is just wasting CPU cycle.
So let's remove it to reduce overhead.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
include/linux/mm.h | 6 ------
mm/pagewalk.c | 18 +-----------------
2 files changed, 1 insertion(+), 23 deletions(-)

diff --git mmotm-2014-05-21-16-57.orig/include/linux/mm.h mmotm-2014-05-21-16-57/include/linux/mm.h
index 563c79ea07bd..b4aa6579f2b1 100644
--- mmotm-2014-05-21-16-57.orig/include/linux/mm.h
+++ mmotm-2014-05-21-16-57/include/linux/mm.h
@@ -1092,8 +1092,6 @@ void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma,

/**
* mm_walk - callbacks for walk_page_range
- * @pgd_entry: if set, called for each non-empty PGD (top-level) entry
- * @pud_entry: if set, called for each non-empty PUD (2nd-level) entry
* @pmd_entry: if set, called for each non-empty PMD (3rd-level) entry
* this handler is required to be able to handle
* pmd_trans_huge() pmds. They may simply choose to
@@ -1115,10 +1113,6 @@ void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
* (see the comment on walk_page_range() for more details)
*/
struct mm_walk {
- int (*pgd_entry)(pgd_t *pgd, unsigned long addr,
- unsigned long next, struct mm_walk *walk);
- int (*pud_entry)(pud_t *pud, unsigned long addr,
- unsigned long next, struct mm_walk *walk);
int (*pmd_entry)(pmd_t *pmd, unsigned long addr,
unsigned long next, struct mm_walk *walk);
int (*pte_entry)(pte_t *pte, unsigned long addr,
diff --git mmotm-2014-05-21-16-57.orig/mm/pagewalk.c mmotm-2014-05-21-16-57/mm/pagewalk.c
index 2eda3dbe0b52..e734f63276c2 100644
--- mmotm-2014-05-21-16-57.orig/mm/pagewalk.c
+++ mmotm-2014-05-21-16-57/mm/pagewalk.c
@@ -115,14 +115,6 @@ static int walk_pud_range(pgd_t *pgd, unsigned long addr,
continue;
}

- if (walk->pud_entry) {
- err = walk->pud_entry(pud, addr, next, walk);
- if (skip_lower_level_walking(walk))
- continue;
- if (err)
- break;
- }
-
if (walk->pmd_entry || walk->pte_entry) {
err = walk_pmd_range(pud, addr, next, walk);
if (err)
@@ -152,15 +144,7 @@ static int walk_pgd_range(unsigned long addr, unsigned long end,
continue;
}

- if (walk->pgd_entry) {
- err = walk->pgd_entry(pgd, addr, next, walk);
- if (skip_lower_level_walking(walk))
- continue;
- if (err)
- break;
- }
-
- if (walk->pud_entry || walk->pmd_entry || walk->pte_entry) {
+ if (walk->pmd_entry || walk->pte_entry) {
err = walk_pud_range(pgd, addr, next, walk);
if (err)
break;
--
1.9.3


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