The patch titled
Subject: mm/ksm: add pages_skipped metric
has been added to the -mm mm-unstable branch. Its filename is
mm-ksm-add-pages_skipped-metric.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-ksm-add-pages_skipped-metric.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/ksm: add pages_skipped metric
Date: Mon, 18 Sep 2023 11:58:14 -0700
This change adds the "pages skipped" metric. To be able to evaluate how
successful smart page scanning is, the pages skipped metric can be
compared to the pages scanned metric.
The pages skipped metric is a cumulative counter. The counter is stored
under /sys/kernel/mm/ksm/pages_skipped.
Link: https://lkml.kernel.org/r/20230918185816.1518366-3-shr@xxxxxxxxxxxx
Signed-off-by: Stefan Roesch <shr@xxxxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/ksm.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
--- a/mm/ksm.c~mm-ksm-add-pages_skipped-metric
+++ a/mm/ksm.c
@@ -293,6 +293,9 @@ static bool ksm_smart_scan;
/* The number of zero pages which is placed by KSM */
unsigned long ksm_zero_pages;
+/* The number of pages that have been skipped due to "smart scanning" */
+static unsigned long ksm_pages_skipped;
+
#ifdef CONFIG_NUMA
/* Zeroed when merging across nodes is not allowed */
static unsigned int ksm_merge_across_nodes = 1;
@@ -2378,6 +2381,7 @@ static bool should_skip_rmap_item(struct
* Skip the page and calculate skip_age on when to re-enable scanning
* for this page.
*/
+ ++ksm_pages_skipped;
if (rmap_item->skip_age == 0) {
rmap_item->skip_age = (age + skip_age(age)) & 0xFF;
remove_rmap_item_from_tree(rmap_item);
@@ -3468,6 +3472,13 @@ static ssize_t pages_volatile_show(struc
}
KSM_ATTR_RO(pages_volatile);
+static ssize_t pages_skipped_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%lu\n", ksm_pages_skipped);
+}
+KSM_ATTR_RO(pages_skipped);
+
static ssize_t ksm_zero_pages_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
@@ -3565,6 +3576,7 @@ static struct attribute *ksm_attrs[] = {
&pages_sharing_attr.attr,
&pages_unshared_attr.attr,
&pages_volatile_attr.attr,
+ &pages_skipped_attr.attr,
&ksm_zero_pages_attr.attr,
&full_scans_attr.attr,
#ifdef CONFIG_NUMA
_
Patches currently in -mm which might be from shr@xxxxxxxxxxxx are
mm-ksm-add-smart-page-scanning-mode.patch
mm-ksm-add-pages_skipped-metric.patch
mm-ksm-document-smart-scan-mode.patch
mm-ksm-document-pages_skipped-sysfs-knob.patch
