diff options
| -rw-r--r-- | Documentation/admin-guide/mm/ksm.rst | 7 | ||||
| -rw-r--r-- | include/linux/ksm.h | 12 | ||||
| -rw-r--r-- | mm/khugepaged.c | 2 | ||||
| -rw-r--r-- | mm/ksm.c | 12 | ||||
| -rw-r--r-- | mm/memory.c | 5 |
5 files changed, 37 insertions, 1 deletions
diff --git a/Documentation/admin-guide/mm/ksm.rst b/Documentation/admin-guide/mm/ksm.rst index 7626392fe82c..6cc919dbfd55 100644 --- a/Documentation/admin-guide/mm/ksm.rst +++ b/Documentation/admin-guide/mm/ksm.rst @@ -173,6 +173,13 @@ stable_node_chains the number of KSM pages that hit the ``max_page_sharing`` limit stable_node_dups number of duplicated KSM pages +ksm_zero_pages + how many zero pages that are still mapped into processes were mapped by + KSM when deduplicating. + +When ``use_zero_pages`` is/was enabled, the sum of ``pages_sharing`` + +``ksm_zero_pages`` represents the actual number of pages saved by KSM. +if ``use_zero_pages`` has never been enabled, ``ksm_zero_pages`` is 0. A high ratio of ``pages_sharing`` to ``pages_shared`` indicates good sharing, but a high ratio of ``pages_unshared`` to ``pages_sharing`` diff --git a/include/linux/ksm.h b/include/linux/ksm.h index 98878107244f..e80aa49009b2 100644 --- a/include/linux/ksm.h +++ b/include/linux/ksm.h @@ -33,6 +33,14 @@ void __ksm_exit(struct mm_struct *mm); */ #define is_ksm_zero_pte(pte) (is_zero_pfn(pte_pfn(pte)) && pte_dirty(pte)) +extern unsigned long ksm_zero_pages; + +static inline void ksm_might_unmap_zero_page(pte_t pte) +{ + if (is_ksm_zero_pte(pte)) + ksm_zero_pages--; +} + static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) { int ret; @@ -101,6 +109,10 @@ static inline void ksm_exit(struct mm_struct *mm) { } +static inline void ksm_might_unmap_zero_page(pte_t pte) +{ +} + #ifdef CONFIG_MEMORY_FAILURE static inline void collect_procs_ksm(struct page *page, struct list_head *to_kill, int force_early) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 78c8d5d8b628..419981dcc889 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -19,6 +19,7 @@ #include <linux/page_table_check.h> #include <linux/swapops.h> #include <linux/shmem_fs.h> +#include <linux/ksm.h> #include <asm/tlb.h> #include <asm/pgalloc.h> @@ -709,6 +710,7 @@ static void __collapse_huge_page_copy_succeeded(pte_t *pte, spin_lock(ptl); ptep_clear(vma->vm_mm, address, _pte); spin_unlock(ptl); + ksm_might_unmap_zero_page(pteval); } } else { src_page = pte_page(pteval); @@ -278,6 +278,9 @@ static unsigned int zero_checksum __read_mostly; /* Whether to merge empty (zeroed) pages with actual zero pages */ static bool ksm_use_zero_pages __read_mostly; +/* The number of zero pages which is placed by KSM */ +unsigned long ksm_zero_pages; + #ifdef CONFIG_NUMA /* Zeroed when merging across nodes is not allowed */ static unsigned int ksm_merge_across_nodes = 1; @@ -1229,6 +1232,7 @@ static int replace_page(struct vm_area_struct *vma, struct page *page, * the dirty bit in zero page's PTE is set. */ newpte = pte_mkdirty(pte_mkspecial(pfn_pte(page_to_pfn(kpage), vma->vm_page_prot))); + ksm_zero_pages++; /* * We're replacing an anonymous page with a zero page, which is * not anonymous. We need to do proper accounting otherwise we @@ -3356,6 +3360,13 @@ static ssize_t pages_volatile_show(struct kobject *kobj, } KSM_ATTR_RO(pages_volatile); +static ssize_t ksm_zero_pages_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%ld\n", ksm_zero_pages); +} +KSM_ATTR_RO(ksm_zero_pages); + static ssize_t general_profit_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { @@ -3423,6 +3434,7 @@ static struct attribute *ksm_attrs[] = { &pages_sharing_attr.attr, &pages_unshared_attr.attr, &pages_volatile_attr.attr, + &ksm_zero_pages_attr.attr, &full_scans_attr.attr, #ifdef CONFIG_NUMA &merge_across_nodes_attr.attr, diff --git a/mm/memory.c b/mm/memory.c index e9f9944c7370..c256da05bb5e 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1433,8 +1433,10 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, tlb_remove_tlb_entry(tlb, pte, addr); zap_install_uffd_wp_if_needed(vma, addr, pte, details, ptent); - if (unlikely(!page)) + if (unlikely(!page)) { + ksm_might_unmap_zero_page(ptent); continue; + } delay_rmap = 0; if (!PageAnon(page)) { @@ -3128,6 +3130,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf) inc_mm_counter(mm, MM_ANONPAGES); } } else { + ksm_might_unmap_zero_page(vmf->orig_pte); inc_mm_counter(mm, MM_ANONPAGES); } flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte)); |