[RFC PATCH v2 08/19] 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 7f3b28b7536e..a0b4611112c0 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -3301,6 +3301,21 @@ static ssize_t zero_pages_sharing_show(struct kobject *kobj,
 }
 KSM_ATTR_RO(zero_pages_sharing);
 
+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)
 {
@@ -3366,6 +3381,7 @@ 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