On Fri, 10 Feb 2023 09:19:49 +0800 (CST)
<yang.yang29@xxxxxxxxxx> wrote:
> From: xu xin <xu.xin16@xxxxxxxxxx>
>
> 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.
>
> 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
> zero_pages_sharing in it.
>
> Cc: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>
> Cc: Xuexin Jiang <jiang.xuexin@xxxxxxxxxx>
> Cc: Xiaokai Ran <ran.xiaokai@xxxxxxxxxx>
> Cc: Yang Yang <yang.yang29@xxxxxxxxxx>
> Signed-off-by: xu xin <xu.xin16@xxxxxxxxxx>
Reviewed-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
> ---
> fs/proc/base.c | 1 +
> include/linux/mm_types.h | 7 ++++++-
> mm/ksm.c | 2 ++
> 3 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 9e479d7d202b..ac9ebe972be0 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -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, "zero_pages_sharing %lu\n", mm->ksm_zero_pages_sharing);
> mmput(mm);
> }
>
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index 4e1031626403..5c734ebc1890 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -776,7 +776,7 @@ struct mm_struct {
> #ifdef CONFIG_KSM
> /*
> * Represent how many pages of this process are involved in KSM
> - * merging.
> + * merging (not including ksm_zero_pages_sharing).
> */
> unsigned long ksm_merging_pages;
> /*
> @@ -784,6 +784,11 @@ struct mm_struct {
> * including merged and not merged.
> */
> unsigned long ksm_rmap_items;
> + /*
> + * Represent how many empty pages are merged with kernel zero
> + * pages when enabling KSM use_zero_pages.
> + */
> + unsigned long ksm_zero_pages_sharing;
> #endif
> #ifdef CONFIG_LRU_GEN
> struct {
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 1fa668e1fe82..42dbcc3ec90d 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -794,6 +794,7 @@ static inline void clean_rmap_item_zero_flag(struct ksm_rmap_item *rmap_item)
> {
> if (rmap_item->address & ZERO_PAGE_FLAG) {
> ksm_zero_pages_sharing--;
> + rmap_item->mm->ksm_zero_pages_sharing--;
> rmap_item->address &= PAGE_MASK;
> }
> }
> @@ -2117,6 +2118,7 @@ static int try_to_merge_with_kernel_zero_page(struct ksm_rmap_item *rmap_item,
> if (!err) {
> rmap_item->address |= ZERO_PAGE_FLAG;
> ksm_zero_pages_sharing++;
> + rmap_item->mm->ksm_zero_pages_sharing++;
> }
> } else {
> /* If the vma is out of date, we do not need to continue. */
