On 22.05.23 12:54, Yang Yang wrote:
From: xu xin <xu.xin16@xxxxxxxxxx>
I suggest changing the subject to
"ksm: consider KSM-placed zeropages when calculating KSM profit"
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.
Signed-off-by: xu xin <xu.xin16@xxxxxxxxxx>
Cc: Xiaokai Ran <ran.xiaokai@xxxxxxxxxx>
Cc: Yang Yang <yang.yang29@xxxxxxxxxx>
Cc: Jiang Xuexin <jiang.xuexin@xxxxxxxxxx>
Cc: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
---
Documentation/admin-guide/mm/ksm.rst | 18 +++++++++++-------
mm/ksm.c | 2 +-
2 files changed, 12 insertions(+), 8 deletions(-)
diff --git a/Documentation/admin-guide/mm/ksm.rst b/Documentation/admin-guide/mm/ksm.rst
index 019dc40a0d3c..dde7c152f0ae 100644
--- a/Documentation/admin-guide/mm/ksm.rst
+++ b/Documentation/admin-guide/mm/ksm.rst
@@ -204,21 +204,25 @@ several times, which are unprofitable memory consumed.
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 alos shown in
s/alos/also/
+ ``/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
diff --git a/mm/ksm.c b/mm/ksm.c
index 4e510f5c5938..d23a240c2519 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -3085,7 +3085,7 @@ 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 */
Apart from that LGTM. CCing Stefan R.
--
Thanks,
David / dhildenb
