[RFC PATCH v2 10/19] mm: calculate ksm process profit metric

[Stefan Roesch <shr@devkernel.io>]

The ksm documentation mentions the process profit metric and how to
calculate it. This adds the calculation of the metric.

Signed-off-by: Stefan Roesch <shr@devkernel.io>
---
 include/linux/ksm.h | 4 ++++
 mm/ksm.c            | 8 ++++++++
 2 files changed, 12 insertions(+)

diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index d38a05a36298..a18cd03efcfb 100644
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -55,6 +55,10 @@ struct page *ksm_might_need_to_copy(struct page *page,
 void rmap_walk_ksm(struct folio *folio, struct rmap_walk_control *rwc);
 void folio_migrate_ksm(struct folio *newfolio, struct folio *folio);
 
+#ifdef CONFIG_PROC_FS
+long ksm_process_profit(struct mm_struct *);
+#endif /* CONFIG_PROC_FS */
+
 #else  /* !CONFIG_KSM */
 
 static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
diff --git a/mm/ksm.c b/mm/ksm.c
index a0b4611112c0..b3db29605303 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -3024,6 +3024,14 @@ static void wait_while_offlining(void)
 }
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 
+#ifdef CONFIG_PROC_FS
+long ksm_process_profit(struct mm_struct *mm)
+{
+	return (long)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.
-- 
2.30.2