The patch titled
ksm: pages_unshared and pages_volatile
has been added to the -mm tree. Its filename is
ksm-pages_unshared-and-pages_volatile.patch
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------------------------------------------------------
Subject: ksm: pages_unshared and pages_volatile
From: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx>
The pages_shared and pages_sharing counts give a good picture of how
successful KSM is at sharing; but no clue to how much wasted work it's
doing to get there. Add pages_unshared (count of unique pages waiting
in the unstable tree, hoping to find a mate) and pages_volatile.
pages_volatile is harder to define. It includes those pages changing
too fast to get into the unstable tree, but also whatever other edge
conditions prevent a page getting into the trees: a high value may
deserve investigation. Don't try to calculate it from the various
conditions: it's the total of rmap_items less those accounted for.
Also show full_scans: the number of completed scans of everything
registered in the mm list.
The locking for all these counts is simply ksm_thread_mutex.
Signed-off-by: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx>
Acked-by: Izik Eidus <ieidus@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/ksm.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 51 insertions(+), 1 deletion(-)
diff -puN mm/ksm.c~ksm-pages_unshared-and-pages_volatile mm/ksm.c
--- a/mm/ksm.c~ksm-pages_unshared-and-pages_volatile
+++ a/mm/ksm.c
@@ -155,6 +155,12 @@ static unsigned long ksm_pages_shared;
/* The number of page slots additionally sharing those nodes */
static unsigned long ksm_pages_sharing;
+/* The number of nodes in the unstable tree */
+static unsigned long ksm_pages_unshared;
+
+/* The number of rmap_items in use: to calculate pages_volatile */
+static unsigned long ksm_rmap_items;
+
/* Limit on the number of unswappable pages used */
static unsigned long ksm_max_kernel_pages;
@@ -204,11 +210,17 @@ static void __init ksm_slab_free(void)
static inline struct rmap_item *alloc_rmap_item(void)
{
- return kmem_cache_zalloc(rmap_item_cache, GFP_KERNEL);
+ struct rmap_item *rmap_item;
+
+ rmap_item = kmem_cache_zalloc(rmap_item_cache, GFP_KERNEL);
+ if (rmap_item)
+ ksm_rmap_items++;
+ return rmap_item;
}
static inline void free_rmap_item(struct rmap_item *rmap_item)
{
+ ksm_rmap_items--;
rmap_item->mm = NULL; /* debug safety */
kmem_cache_free(rmap_item_cache, rmap_item);
}
@@ -419,6 +431,7 @@ static void remove_rmap_item_from_tree(s
BUG_ON(age > 2);
if (!age)
rb_erase(&rmap_item->node, &root_unstable_tree);
+ ksm_pages_unshared--;
}
rmap_item->address &= PAGE_MASK;
@@ -1002,6 +1015,7 @@ static struct rmap_item *unstable_tree_s
rb_link_node(&rmap_item->node, parent, new);
rb_insert_color(&rmap_item->node, &root_unstable_tree);
+ ksm_pages_unshared++;
return NULL;
}
@@ -1098,6 +1112,8 @@ static void cmp_and_merge_page(struct pa
if (!err) {
rb_erase(&tree_rmap_item->node, &root_unstable_tree);
tree_rmap_item->address &= ~NODE_FLAG;
+ ksm_pages_unshared--;
+
/*
* If we fail to insert the page into the stable tree,
* we will have 2 virtual addresses that are pointing
@@ -1481,6 +1497,37 @@ static ssize_t pages_sharing_show(struct
}
KSM_ATTR_RO(pages_sharing);
+static ssize_t pages_unshared_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%lu\n", ksm_pages_unshared);
+}
+KSM_ATTR_RO(pages_unshared);
+
+static ssize_t pages_volatile_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ long ksm_pages_volatile;
+
+ ksm_pages_volatile = ksm_rmap_items - ksm_pages_shared
+ - ksm_pages_sharing - ksm_pages_unshared;
+ /*
+ * It was not worth any locking to calculate that statistic,
+ * but it might therefore sometimes be negative: conceal that.
+ */
+ if (ksm_pages_volatile < 0)
+ ksm_pages_volatile = 0;
+ return sprintf(buf, "%ld\n", ksm_pages_volatile);
+}
+KSM_ATTR_RO(pages_volatile);
+
+static ssize_t full_scans_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%lu\n", ksm_scan.seqnr);
+}
+KSM_ATTR_RO(full_scans);
+
static struct attribute *ksm_attrs[] = {
&sleep_millisecs_attr.attr,
&pages_to_scan_attr.attr,
@@ -1488,6 +1535,9 @@ static struct attribute *ksm_attrs[] = {
&max_kernel_pages_attr.attr,
&pages_shared_attr.attr,
&pages_sharing_attr.attr,
+ &pages_unshared_attr.attr,
+ &pages_volatile_attr.attr,
+ &full_scans_attr.attr,
NULL,
};
_
Patches currently in -mm which might be from hugh.dickins@xxxxxxxxxxxxx are
acpi-fix-null-bug-for-hid-uid-string.patch
mm-oom-analysis-add-shmem-vmstat.patch
ksm-add-mmu_notifier-set_pte_at_notify.patch
ksm-first-tidy-up-madvise_vma.patch
ksm-define-madv_mergeable-and-madv_unmergeable.patch
ksm-the-mm-interface-to-ksm.patch
ksm-no-debug-in-page_dup_rmap.patch
ksm-identify-pageksm-pages.patch
ksm-kernel-samepage-merging.patch
ksm-prevent-mremap-move-poisoning.patch
ksm-change-copyright-message.patch
ksm-change-ksm-nice-level-to-be-5.patch
ksm-rename-kernel_pages_allocated.patch
ksm-move-pages_sharing-updates.patch
ksm-pages_unshared-and-pages_volatile.patch
ksm-break-cow-once-unshared.patch
ksm-keep-quiet-while-list-empty.patch
ksm-five-little-cleanups.patch
ksm-fix-endless-loop-on-oom.patch
ksm-distribute-remove_mm_from_lists.patch
ksm-fix-oom-deadlock.patch
ksm-sysfs-and-defaults.patch
ksm-add-some-documentation.patch
ksm-remove-vm_mergeable_flags.patch
getrusage-fill-ru_maxrss-value.patch
getrusage-fill-ru_maxrss-value-update.patch
ramfs-move-ramfs_magic-to-include-linux-magich.patch
memory-controller-soft-limit-organize-cgroups-v9-fix.patch
prio_tree-debugging-patch.patch
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