[RFC PATCH V0 08/10] vmstat: Add vmstat counters

[Raghavendra K T <raghavendra.kt@amd.com>]

Add vmstat counter to track scanning, migration and
type of pages. 

Signed-off-by: Raghavendra K T <raghavendra.kt@amd.com>
---
 include/linux/mm.h            | 11 ++++++++
 include/linux/vm_event_item.h | 10 +++++++
 mm/kmmscand.c                 | 50 ++++++++++++++++++++++++++++++++++-
 mm/vmstat.c                   | 10 +++++++
 4 files changed, 80 insertions(+), 1 deletion(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index c39c4945946c..306452c11d31 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -681,6 +681,17 @@ struct vm_operations_struct {
 					  unsigned long addr);
 };
 
+#ifdef CONFIG_KMMSCAND
+void count_kmmscand_mm_scans(void);
+void count_kmmscand_vma_scans(void);
+void count_kmmscand_migadded(void);
+void count_kmmscand_migrated(void);
+void count_kmmscand_migrate_failed(void);
+void count_kmmscand_slowtier(void);
+void count_kmmscand_toptier(void);
+void count_kmmscand_idlepage(void);
+#endif
+
 #ifdef CONFIG_NUMA_BALANCING
 static inline void vma_numab_state_init(struct vm_area_struct *vma)
 {
diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index f70d0958095c..b2ccd4f665aa 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -65,6 +65,16 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 		NUMA_HINT_FAULTS_LOCAL,
 		NUMA_PAGE_MIGRATE,
 #endif
+#ifdef CONFIG_KMMSCAND
+		KMMSCAND_MM_SCANS,
+		KMMSCAND_VMA_SCANS,
+		KMMSCAND_MIGADDED,
+		KMMSCAND_MIGRATED,
+		KMMSCAND_MIGRATE_FAILED,
+		KMMSCAND_SLOWTIER,
+		KMMSCAND_TOPTIER,
+		KMMSCAND_IDLEPAGE,
+#endif
 #ifdef CONFIG_MIGRATION
 		PGMIGRATE_SUCCESS, PGMIGRATE_FAIL,
 		THP_MIGRATION_SUCCESS,
diff --git a/mm/kmmscand.c b/mm/kmmscand.c
index 344a45bd2d3e..682c0523c0b4 100644
--- a/mm/kmmscand.c
+++ b/mm/kmmscand.c
@@ -279,6 +279,39 @@ struct attribute_group kmmscand_attr_group = {
 };
 #endif
 
+void count_kmmscand_mm_scans(void)
+{
+	count_vm_numa_event(KMMSCAND_MM_SCANS);
+}
+void count_kmmscand_vma_scans(void)
+{
+	count_vm_numa_event(KMMSCAND_VMA_SCANS);
+}
+void count_kmmscand_migadded(void)
+{
+	count_vm_numa_event(KMMSCAND_MIGADDED);
+}
+void count_kmmscand_migrated(void)
+{
+	count_vm_numa_event(KMMSCAND_MIGRATED);
+}
+void count_kmmscand_migrate_failed(void)
+{
+	count_vm_numa_event(KMMSCAND_MIGRATE_FAILED);
+}
+void count_kmmscand_slowtier(void)
+{
+	count_vm_numa_event(KMMSCAND_SLOWTIER);
+}
+void count_kmmscand_toptier(void)
+{
+	count_vm_numa_event(KMMSCAND_TOPTIER);
+}
+void count_kmmscand_idlepage(void)
+{
+	count_vm_numa_event(KMMSCAND_IDLEPAGE);
+}
+
 static int kmmscand_has_work(void)
 {
 	return !list_empty(&kmmscand_scan.mm_head);
@@ -500,6 +533,9 @@ static int hot_vma_idle_pte_entry(pte_t *pte,
 
 	srcnid = folio_nid(folio);
 
+	if (node_is_toptier(srcnid))
+		count_kmmscand_toptier();
+
 	if (!folio_test_idle(folio) || folio_test_young(folio) ||
 			mmu_notifier_test_young(mm, addr) ||
 			folio_test_referenced(folio) || pte_young(pteval)) {
@@ -511,6 +547,7 @@ static int hot_vma_idle_pte_entry(pte_t *pte,
 		info = kzalloc(sizeof(struct kmmscand_migrate_info), GFP_KERNEL);
 		if (info && migrate_list) {
 
+			count_kmmscand_slowtier();
 			info->mm = mm;
 			info->vma = vma;
 			info->folio = folio;
@@ -524,8 +561,10 @@ static int hot_vma_idle_pte_entry(pte_t *pte,
 			 * XXX: We are increamenting atomic var under mmap_readlock
 			 */
 			atomic_long_inc(&mm->nr_accessed);
+			count_kmmscand_migadded();
 		}
-	}
+	} else
+		count_kmmscand_idlepage();
 end:
 	folio_set_idle(folio);
 	folio_put(folio);
@@ -632,6 +671,12 @@ static void kmmscand_migrate_folio(void)
 			if (info->mm)
 				ret = kmmscand_promote_folio(info);
 
+			/* TBD: encode migrated count here, currently assume folio_nr_pages */
+			if (!ret)
+				count_kmmscand_migrated();
+			else
+				count_kmmscand_migrate_failed();
+
 			kfree(info);
 
 			spin_lock(&kmmscand_migrate_lock);
@@ -799,6 +844,7 @@ static unsigned long kmmscand_scan_mm_slot(void)
 	for_each_vma(vmi, vma) {
 		/* Count the scanned pages here to decide exit */
 		kmmscand_walk_page_vma(vma);
+		count_kmmscand_vma_scans();
 		scanned_size += vma->vm_end - vma->vm_start;
 		address = vma->vm_end;
 
@@ -822,6 +868,8 @@ static unsigned long kmmscand_scan_mm_slot(void)
 
 	update_mmslot_info = true;
 
+	count_kmmscand_mm_scans();
+
 outerloop:
 	/* exit_mmap will destroy ptes after this */
 	mmap_read_unlock(mm);
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 4d016314a56c..d758e7155042 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1340,6 +1340,16 @@ const char * const vmstat_text[] = {
 	"numa_hint_faults_local",
 	"numa_pages_migrated",
 #endif
+#ifdef CONFIG_KMMSCAND
+	"nr_kmmscand_mm_scans",
+	"nr_kmmscand_vma_scans",
+	"nr_kmmscand_migadded",
+	"nr_kmmscand_migrated",
+	"nr_kmmscand_migrate_failed",
+	"nr_kmmscand_slowtier",
+	"nr_kmmscand_toptier",
+	"nr_kmmscand_idlepage",
+#endif
 #ifdef CONFIG_MIGRATION
 	"pgmigrate_success",
 	"pgmigrate_fail",
-- 
2.39.3