+ ksm-consider-ksm-placed-zeropages-when-calculating-ksm-profit.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: ksm: consider KSM-placed zeropages when calculating KSM profit
has been added to the -mm mm-unstable branch.  Its filename is
     ksm-consider-ksm-placed-zeropages-when-calculating-ksm-profit.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/ksm-consider-ksm-placed-zeropages-when-calculating-ksm-profit.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: xu xin <xu.xin16@zte.com.cn>
Subject: ksm: consider KSM-placed zeropages when calculating KSM profit
Date: Tue, 13 Jun 2023 11:09:42 +0800

When use_zero_pages is enabled, the calculation of ksm profit is not
correct because ksm zero pages is not counted in.  So update the
calculation of KSM profit including the documentation.

Link: https://lkml.kernel.org/r/20230613030942.186041-1-yang.yang29@zte.com.cn
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Xiaokai Ran <ran.xiaokai@zte.com.cn>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: Jiang Xuexin <jiang.xuexin@zte.com.cn>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 Documentation/admin-guide/mm/ksm.rst |   18 +++++++++++-------
 mm/ksm.c                             |    4 ++--
 2 files changed, 13 insertions(+), 9 deletions(-)

--- a/Documentation/admin-guide/mm/ksm.rst~ksm-consider-ksm-placed-zeropages-when-calculating-ksm-profit
+++ a/Documentation/admin-guide/mm/ksm.rst
@@ -203,21 +203,25 @@ several times, which are unprofitable me
 1) How to determine whether KSM save memory or consume memory in system-wide
    range? Here is a simple approximate calculation for reference::
 
-	general_profit =~ pages_sharing * sizeof(page) - (all_rmap_items) *
+	general_profit =~ ksm_saved_pages * sizeof(page) - (all_rmap_items) *
 			  sizeof(rmap_item);
 
-   where all_rmap_items can be easily obtained by summing ``pages_sharing``,
-   ``pages_shared``, ``pages_unshared`` and ``pages_volatile``.
+   where ksm_saved_pages equals to the sum of ``pages_sharing`` +
+   ``ksm_zero_pages`` of the system, and all_rmap_items can be easily
+   obtained by summing ``pages_sharing``, ``pages_shared``, ``pages_unshared``
+   and ``pages_volatile``.
 
 2) The KSM profit inner a single process can be similarly obtained by the
    following approximate calculation::
 
-	process_profit =~ ksm_merging_pages * sizeof(page) -
+	process_profit =~ ksm_saved_pages * sizeof(page) -
 			  ksm_rmap_items * sizeof(rmap_item).
 
-   where ksm_merging_pages is shown under the directory ``/proc/<pid>/``,
-   and ksm_rmap_items is shown in ``/proc/<pid>/ksm_stat``. The process profit
-   is also shown in ``/proc/<pid>/ksm_stat`` as ksm_process_profit.
+   where ksm_saved_pages equals to the sum of ``ksm_merging_pages`` and
+   ``ksm_zero_pages``, both of which are shown under the directory
+   ``/proc/<pid>/ksm_stat``, and ksm_rmap_items is also shown in
+   ``/proc/<pid>/ksm_stat``. The process profit is also shown in
+   ``/proc/<pid>/ksm_stat`` as ksm_process_profit.
 
 From the perspective of application, a high ratio of ``ksm_rmap_items`` to
 ``ksm_merging_pages`` means a bad madvise-applied policy, so developers or
--- a/mm/ksm.c~ksm-consider-ksm-placed-zeropages-when-calculating-ksm-profit
+++ a/mm/ksm.c
@@ -3092,7 +3092,7 @@ static void wait_while_offlining(void)
 #ifdef CONFIG_PROC_FS
 long ksm_process_profit(struct mm_struct *mm)
 {
-	return mm->ksm_merging_pages * PAGE_SIZE -
+	return (long)(mm->ksm_merging_pages + mm->ksm_zero_pages) * PAGE_SIZE -
 		mm->ksm_rmap_items * sizeof(struct ksm_rmap_item);
 }
 #endif /* CONFIG_PROC_FS */
@@ -3373,7 +3373,7 @@ static ssize_t general_profit_show(struc
 {
 	long general_profit;
 
-	general_profit = ksm_pages_sharing * PAGE_SIZE -
+	general_profit = (ksm_pages_sharing + ksm_zero_pages) * PAGE_SIZE -
 				ksm_rmap_items * sizeof(struct ksm_rmap_item);
 
 	return sysfs_emit(buf, "%ld\n", general_profit);
_

Patches currently in -mm which might be from xu.xin16@zte.com.cn are

ksm-support-unsharing-ksm-placed-zero-pages.patch
ksm-count-all-zero-pages-placed-by-ksm.patch
ksm-add-ksm-zero-pages-for-each-process.patch
ksm-consider-ksm-placed-zeropages-when-calculating-ksm-profit.patch
selftest-add-a-testcase-of-ksm-zero-pages.patch