[RESEND RFC PATCH v1 09/20] mm: expose general_profit metric

[Stefan Roesch <shr@devkernel.io>]

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.

Signed-off-by: Stefan Roesch <shr@devkernel.io>
---
 mm/ksm.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/mm/ksm.c b/mm/ksm.c
index 19f434f97dc1..d29454a802a0 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -3205,6 +3205,21 @@ static ssize_t pages_volatile_show(struct kobject *kobj,
 }
 KSM_ATTR_RO(pages_volatile);
 
+static ssize_t general_profit_show(struct kobject *kobj,
+				   struct kobj_attribute *attr, char *buf)
+{
+	long general_profit;
+	long all_rmap_items;
+
+	all_rmap_items = ksm_max_page_sharing + ksm_pages_shared +
+				ksm_pages_unshared + pages_volatile();
+	general_profit = ksm_pages_sharing * PAGE_SIZE -
+				all_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)
 {
@@ -3269,6 +3284,7 @@ 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,
 };
 
-- 
2.30.2