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authorxu xin <xu.xin16@zte.com.cn>2023-06-13 06:09:42 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-08-18 20:12:10 +0300
commit1a8e84305783bddbae708f28178c6d0aa6321913 (patch)
tree17b13c3f2ff6b91b3ee2d494d1a9646fc518972d /Documentation
parent6080d19f07043ade61094d0f58b14c05e1694a39 (diff)
downloadlinux-1a8e84305783bddbae708f28178c6d0aa6321913.tar.xz
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. 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>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/admin-guide/mm/ksm.rst18
1 files changed, 11 insertions, 7 deletions
diff --git a/Documentation/admin-guide/mm/ksm.rst b/Documentation/admin-guide/mm/ksm.rst
index 6cc919dbfd55..5c5be7bd84b8 100644
--- a/Documentation/admin-guide/mm/ksm.rst
+++ b/Documentation/admin-guide/mm/ksm.rst
@@ -203,21 +203,25 @@ 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 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