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Subject[PATCH v2 5/5] mm: optimise pte dirty/accessed bit setting by demand based pte insertion
Date
Similarly to the previous patch, this tries to optimise dirty/accessed
bits in ptes to avoid access costs of hardware setting them.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
mm/huge_memory.c | 12 ++++++++----
mm/memory.c | 9 ++++++---
2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 1f43265204d4..38c2cd3b4879 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1197,6 +1197,7 @@ static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf,
for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
pte_t entry;
entry = mk_pte(pages[i], vma->vm_page_prot);
+ entry = pte_mkyoung(entry);
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
memcg = (void *)page_private(pages[i]);
set_page_private(pages[i], 0);
@@ -2067,7 +2068,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
struct page *page;
pgtable_t pgtable;
pmd_t old_pmd, _pmd;
- bool young, write, soft_dirty, pmd_migration = false;
+ bool young, write, dirty, soft_dirty, pmd_migration = false;
unsigned long addr;
int i;

@@ -2145,7 +2146,8 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
page = pmd_page(old_pmd);
VM_BUG_ON_PAGE(!page_count(page), page);
page_ref_add(page, HPAGE_PMD_NR - 1);
- if (pmd_dirty(old_pmd))
+ dirty = pmd_dirty(old_pmd);
+ if (dirty)
SetPageDirty(page);
write = pmd_write(old_pmd);
young = pmd_young(old_pmd);
@@ -2176,8 +2178,10 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
entry = maybe_mkwrite(entry, vma);
if (!write)
entry = pte_wrprotect(entry);
- if (!young)
- entry = pte_mkold(entry);
+ if (young)
+ entry = pte_mkyoung(entry);
+ if (dirty)
+ entry = pte_mkdirty(entry);
if (soft_dirty)
entry = pte_mksoft_dirty(entry);
}
diff --git a/mm/memory.c b/mm/memory.c
index 9e314339a0bd..f907ea7a6303 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1804,10 +1804,9 @@ static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
entry = pte_mkspecial(pfn_t_pte(pfn, prot));

out_mkwrite:
- if (mkwrite) {
- entry = pte_mkyoung(entry);
+ entry = pte_mkyoung(entry);
+ if (mkwrite)
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
- }

set_pte_at(mm, addr, pte, entry);
update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
@@ -2534,6 +2533,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
}
flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
entry = mk_pte(new_page, vma->vm_page_prot);
+ entry = pte_mkyoung(entry);
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
/*
* Clear the pte entry and flush it first, before updating the
@@ -3043,6 +3043,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
pte = mk_pte(page, vma->vm_page_prot);
+ pte = pte_mkyoung(pte);
if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
pte = maybe_mkwrite(pte_mkdirty(pte), vma);
vmf->flags &= ~FAULT_FLAG_WRITE;
@@ -3185,6 +3186,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
__SetPageUptodate(page);

entry = mk_pte(page, vma->vm_page_prot);
+ entry = pte_mkyoung(entry);
if (vma->vm_flags & VM_WRITE)
entry = pte_mkwrite(pte_mkdirty(entry));

@@ -3453,6 +3455,7 @@ vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,

flush_icache_page(vma, page);
entry = mk_pte(page, vma->vm_page_prot);
+ entry = pte_mkyoung(entry);
if (write)
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
/* copy-on-write page */
--
2.18.0
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