[RFC PATCH v2 15/15] mm: Print memory region statistics to understand the buddy allocator behavior

["Srivatsa S. Bhat" <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>]

In order to observe the behavior of the region-aware buddy allocator, modify
vmstat.c to also print memory region related statistics. In particular, enable
memory region-related info in /proc/zoneinfo and /proc/buddyinfo, since they
would help us to atleast (roughly) observe how the new buddy allocator is
behaving.

For now, the region statistics correspond to the zone memory regions and not
the (absolute) node memory regions, and some of the statistics (especially the
no. of present pages) might not be very accurate. But since we account for
and print the free page statistics for every zone memory region accurately, we
should be able to observe the new page allocator behavior to a reasonable
degree of accuracy.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
---

 mm/vmstat.c |   34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 63e12f0..1a90475 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -825,11 +825,28 @@ const char * const vmstat_text[] = {
 static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
 						struct zone *zone)
 {
-	int order;
+	int i, order, t;
+	struct free_area *area;
 
-	seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
-	for (order = 0; order < MAX_ORDER; ++order)
-		seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
+	seq_printf(m, "Node %d, zone %8s \n", pgdat->node_id, zone->name);
+
+	for (i = 0; i < zone->nr_zone_regions; i++) {
+
+		seq_printf(m, "\t\t Region %d ", i);
+
+		for (order = 0; order < MAX_ORDER; ++order) {
+			unsigned long nr_free = 0;
+
+			area = &zone->free_area[order];
+
+			for (t = 0; t < MIGRATE_TYPES; t++) {
+				nr_free +=
+					area->free_list[t].mr_list[i].nr_free;
+			}
+			seq_printf(m, "%6lu ", nr_free);
+		}
+		seq_putc(m, '\n');
+	}
 	seq_putc(m, '\n');
 }
 
@@ -1016,6 +1033,15 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 		   zone->present_pages,
 		   zone->managed_pages);
 
+	seq_printf(m, "\n\nPer-region page stats\t present\t free\n\n");
+	for (i = 0; i < zone->nr_zone_regions; i++) {
+		struct zone_mem_region *region;
+
+		region = &zone->zone_regions[i];
+		seq_printf(m, "\tRegion %d \t %6lu \t %6lu\n", i,
+				region->present_pages, region->nr_free);
+	}
+
 	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 		seq_printf(m, "\n    %-12s %lu", vmstat_text[i],
 				zone_page_state(zone, i));

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