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>
---
fs/proc/base.c | 1 +
include/linux/mm_types.h | 7 ++++++-
mm/ksm.c | 6 +++++-
3 files changed, 12 insertions(+), 2 deletions(-)
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 500e536796ca..78a4ee264645 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -691,7 +691,7 @@ 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;
/*
@@ -699,6 +699,11 @@ 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 2970a7062db6..c049a95afc26 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -546,8 +546,10 @@ static inline int unshare_zero_pages(struct ksm_rmap_item *rmap_item)
static inline void free_rmap_item(struct ksm_rmap_item *rmap_item)
{
if (rmap_item->address & ZERO_PAGE_FLAG) {
- if (!unshare_zero_pages(rmap_item))
+ if (!unshare_zero_pages(rmap_item)) {
ksm_zero_pages_sharing--;
+ rmap_item->mm->ksm_zero_pages_sharing--;
+ }
}
ksm_rmap_items--;
rmap_item->mm->ksm_rmap_items--;
@@ -2083,6 +2085,7 @@ static int try_to_merge_with_kernel_zero_page(struct mm_struct *mm,
if (!err) {
rmap_item->address |= ZERO_PAGE_FLAG;
ksm_zero_pages_sharing++;
+ rmap_item->mm->ksm_zero_pages_sharing++;
}
}
@@ -2186,6 +2189,7 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite
*/
rmap_item->address &= PAGE_MASK;
ksm_zero_pages_sharing--;
+ rmap_item->mm->ksm_zero_pages_sharing--;
}
}
--
2.25.1
