The patch titled
Subject: mm: add new KSM process and sysfs knobs
has been added to the -mm mm-unstable branch. Its filename is
mm-add-new-ksm-process-and-sysfs-knobs.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-add-new-ksm-process-and-sysfs-knobs.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: Stefan Roesch <shr@xxxxxxxxxxxx>
Subject: mm: add new KSM process and sysfs knobs
Date: Mon, 17 Apr 2023 22:13:41 -0700
This adds the general_profit KSM sysfs knob and the process profit metric
knobs to ksm_stat.
1) expose general_profit metric
The documentation mentions a general profit metric, however this
metric is not calculated. In addition the formula depends on the size
of internal structures, which makes it more difficult for an
administrator to make the calculation. Adding the metric for a better
user experience.
2) document general_profit sysfs knob
3) calculate ksm process profit metric
The ksm documentation mentions the process profit metric and how to
calculate it. This adds the calculation of the metric.
4) mm: expose ksm process profit metric in ksm_stat
This exposes the ksm process profit metric in /proc/<pid>/ksm_stat.
The documentation mentions the formula for the ksm process profit
metric, however it does not calculate it. In addition the formula
depends on the size of internal structures. So it makes sense to
expose it.
5) document new procfs ksm knobs
Link: https://lkml.kernel.org/r/20230418051342.1919757-3-shr@xxxxxxxxxxxx
Signed-off-by: Stefan Roesch <shr@xxxxxxxxxxxx>
Reviewed-by: Bagas Sanjaya <bagasdotme@xxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/ABI/testing/sysfs-kernel-mm-ksm | 8 ++++++
Documentation/admin-guide/mm/ksm.rst | 5 +++
fs/proc/base.c | 3 ++
include/linux/ksm.h | 5 +++
mm/ksm.c | 21 ++++++++++++++++
5 files changed, 41 insertions(+), 1 deletion(-)
--- a/Documentation/ABI/testing/sysfs-kernel-mm-ksm~mm-add-new-ksm-process-and-sysfs-knobs
+++ a/Documentation/ABI/testing/sysfs-kernel-mm-ksm
@@ -51,3 +51,11 @@ Description: Control merging pages acros
When it is set to 0 only pages from the same node are merged,
otherwise pages from all nodes can be merged together (default).
+
+What: /sys/kernel/mm/ksm/general_profit
+Date: April 2023
+KernelVersion: 6.4
+Contact: Linux memory management mailing list <linux-mm@xxxxxxxxx>
+Description: Measure how effective KSM is.
+ general_profit: how effective is KSM. The formula for the
+ calculation is in Documentation/admin-guide/mm/ksm.rst.
--- a/Documentation/admin-guide/mm/ksm.rst~mm-add-new-ksm-process-and-sysfs-knobs
+++ a/Documentation/admin-guide/mm/ksm.rst
@@ -157,6 +157,8 @@ stable_node_chains_prune_millisecs
The effectiveness of KSM and MADV_MERGEABLE is shown in ``/sys/kernel/mm/ksm/``:
+general_profit
+ how effective is KSM. The calculation is explained below.
pages_shared
how many shared pages are being used
pages_sharing
@@ -207,7 +209,8 @@ several times, which are unprofitable me
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``.
+ 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.
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/fs/proc/base.c~mm-add-new-ksm-process-and-sysfs-knobs
+++ a/fs/proc/base.c
@@ -96,6 +96,7 @@
#include <linux/time_namespace.h>
#include <linux/resctrl.h>
#include <linux/cn_proc.h>
+#include <linux/ksm.h>
#include <trace/events/oom.h>
#include "internal.h"
#include "fd.h"
@@ -3207,6 +3208,8 @@ static int proc_pid_ksm_stat(struct seq_
mm = get_task_mm(task);
if (mm) {
seq_printf(m, "ksm_rmap_items %lu\n", mm->ksm_rmap_items);
+ seq_printf(m, "ksm_merging_pages %lu\n", mm->ksm_merging_pages);
+ seq_printf(m, "ksm_process_profit %ld\n", ksm_process_profit(mm));
mmput(mm);
}
--- a/include/linux/ksm.h~mm-add-new-ksm-process-and-sysfs-knobs
+++ a/include/linux/ksm.h
@@ -68,6 +68,11 @@ void folio_migrate_ksm(struct folio *new
void collect_procs_ksm(struct page *page, struct list_head *to_kill,
int force_early);
#endif
+
+#ifdef CONFIG_PROC_FS
+long ksm_process_profit(struct mm_struct *);
+#endif /* CONFIG_PROC_FS */
+
#else /* !CONFIG_KSM */
static inline void ksm_add_vma(struct vm_area_struct *vma)
--- a/mm/ksm.c~mm-add-new-ksm-process-and-sysfs-knobs
+++ a/mm/ksm.c
@@ -3007,6 +3007,14 @@ static void wait_while_offlining(void)
}
#endif /* CONFIG_MEMORY_HOTREMOVE */
+#ifdef CONFIG_PROC_FS
+long ksm_process_profit(struct mm_struct *mm)
+{
+ return mm->ksm_merging_pages * PAGE_SIZE -
+ mm->ksm_rmap_items * sizeof(struct ksm_rmap_item);
+}
+#endif /* CONFIG_PROC_FS */
+
#ifdef CONFIG_SYSFS
/*
* This all compiles without CONFIG_SYSFS, but is a waste of space.
@@ -3271,6 +3279,18 @@ static ssize_t pages_volatile_show(struc
}
KSM_ATTR_RO(pages_volatile);
+static ssize_t general_profit_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ long general_profit;
+
+ general_profit = ksm_pages_sharing * PAGE_SIZE -
+ ksm_rmap_items * sizeof(struct ksm_rmap_item);
+
+ return sysfs_emit(buf, "%ld\n", general_profit);
+}
+KSM_ATTR_RO(general_profit);
+
static ssize_t stable_node_dups_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
@@ -3335,6 +3355,7 @@ static struct attribute *ksm_attrs[] = {
&stable_node_dups_attr.attr,
&stable_node_chains_prune_millisecs_attr.attr,
&use_zero_pages_attr.attr,
+ &general_profit_attr.attr,
NULL,
};
_
Patches currently in -mm which might be from shr@xxxxxxxxxxxx are
mm-add-new-api-to-enable-ksm-per-process.patch
mm-add-new-ksm-process-and-sysfs-knobs.patch
selftests-mm-add-new-selftests-for-ksm.patch
