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ksm: add ksm zero pages for each process

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As the number of ksm zero pages is not included in ksm_merging_pages per
process when enabling use_zero_pages, it's unclear of how many actual
pages are merged by KSM. To let users accurately estimate their memory
demands when unsharing KSM zero-pages, it's necessary to show KSM zero-
pages per process. In addition, it help users to know the actual KSM
profit because KSM-placed zero pages are also benefit from KSM.

since unsharing zero pages placed by KSM accurately is achieved, then
tracking empty pages merging and unmerging is not a difficult thing any
longer.

Since we already have /proc/<pid>/ksm_stat, just add the information of
'ksm_zero_pages' in it.

Link: https://lkml.kernel.org/r/20230613030938.185993-1-yang.yang29@zte.com.cn
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Xiaokai Ran <ran.xiaokai@zte.com.cn>
Reviewed-by: Yang Yang <yang.yang29@zte.com.cn>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Xuexin Jiang <jiang.xuexin@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
xu xin 2023-06-13 11:09:38 +08:00 committed by Andrew Morton
parent e2942062e0
commit 6080d19f07
6 changed files with 17 additions and 8 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
fs/proc/base.c
View file

@ -3207,6 +3207,7 @@ static int proc_pid_ksm_stat(struct seq_file *m, struct pid_namespace *ns,
mm = get_task_mm(task);
if (mm) {
seq_printf(m, "ksm_rmap_items %lu\n", mm->ksm_rmap_items);
seq_printf(m, "ksm_zero_pages %lu\n", mm->ksm_zero_pages);
seq_printf(m, "ksm_merging_pages %lu\n", mm->ksm_merging_pages);
seq_printf(m, "ksm_process_profit %ld\n", ksm_process_profit(mm));
mmput(mm);

8
include/linux/ksm.h
View file

@ -35,10 +35,12 @@ void __ksm_exit(struct mm_struct *mm);
extern unsigned long ksm_zero_pages;
static inline void ksm_might_unmap_zero_page(pte_t pte)
static inline void ksm_might_unmap_zero_page(struct mm_struct *mm, pte_t pte)
{
if (is_ksm_zero_pte(pte))
if (is_ksm_zero_pte(pte)) {
ksm_zero_pages--;
mm->ksm_zero_pages--;
}
}
static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
@ -109,7 +111,7 @@ static inline void ksm_exit(struct mm_struct *mm)
{
}
static inline void ksm_might_unmap_zero_page(pte_t pte)
static inline void ksm_might_unmap_zero_page(struct mm_struct *mm, pte_t pte)
{
}

9
include/linux/mm_types.h
View file

@ -812,7 +812,7 @@ struct mm_struct {
#ifdef CONFIG_KSM
/*
* Represent how many pages of this process are involved in KSM
* merging.
* merging (not including ksm_zero_pages).
*/
unsigned long ksm_merging_pages;
/*
@ -820,7 +820,12 @@ struct mm_struct {
* including merged and not merged.
*/
unsigned long ksm_rmap_items;
#endif
/*
* Represent how many empty pages are merged with kernel zero
* pages when enabling KSM use_zero_pages.
*/
unsigned long ksm_zero_pages;
#endif /* CONFIG_KSM */
#ifdef CONFIG_LRU_GEN
struct {
/* this mm_struct is on lru_gen_mm_list */

2
mm/khugepaged.c
View file

@ -710,7 +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);
ksm_might_unmap_zero_page(vma->vm_mm, pteval);
}
} else {
src_page = pte_page(pteval);

1
mm/ksm.c
View file

@ -1233,6 +1233,7 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
*/
newpte = pte_mkdirty(pte_mkspecial(pfn_pte(page_to_pfn(kpage), vma->vm_page_prot)));
ksm_zero_pages++;
mm->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

4
mm/memory.c
View file

@ -1434,7 +1434,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
zap_install_uffd_wp_if_needed(vma, addr, pte, details,
ptent);
if (unlikely(!page)) {
ksm_might_unmap_zero_page(ptent);
ksm_might_unmap_zero_page(mm, ptent);
continue;
}
@ -3130,7 +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);
ksm_might_unmap_zero_page(mm, vmf->orig_pte);
inc_mm_counter(mm, MM_ANONPAGES);
}
flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));