mm, compaction: add vmstats for kcompactd work

A "compact_daemon_wake" vmstat exists that represents the number of
times kcompactd has woken up.  This doesn't represent how much work it
actually did, though.

It's useful to understand how much compaction work is being done by
kcompactd versus other methods such as direct compaction and explicitly
triggered per-node (or system) compaction.

This adds two new vmstats: "compact_daemon_migrate_scanned" and
"compact_daemon_free_scanned" to represent the number of pages kcompactd
has scanned as part of its migration scanner and freeing scanner,
respectively.

These values are still accounted for in the general
"compact_migrate_scanned" and "compact_free_scanned" for compatibility.

It could be argued that explicitly triggered compaction could also be
tracked separately, and that could be added if others find it useful.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1612071749390.69852@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 19 insertions, 3 deletions

diff --git a/mm/compaction.c b/mm/compaction.c
index 949198d01260..c6178bbd3e04 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -548,7 +548,7 @@ isolate_fail:
         if (blockpfn == end_pfn)
                 update_pageblock_skip(cc, valid_page, total_isolated, false);
 
-        count_compact_events(COMPACTFREE_SCANNED, nr_scanned);
+        cc->total_free_scanned += nr_scanned;
         if (total_isolated)
                 count_compact_events(COMPACTISOLATED, total_isolated);
         return total_isolated;
@@ -931,7 +931,7 @@ isolate_fail:
         trace_mm_compaction_isolate_migratepages(start_pfn, low_pfn,
                                                 nr_scanned, nr_isolated);
 
-        count_compact_events(COMPACTMIGRATE_SCANNED, nr_scanned);
+        cc->total_migrate_scanned += nr_scanned;
         if (nr_isolated)
                 count_compact_events(COMPACTISOLATED, nr_isolated);
 
@@ -1631,6 +1631,9 @@ out:
                         zone->compact_cached_free_pfn = free_pfn;
         }
 
+        count_compact_events(COMPACTMIGRATE_SCANNED, cc->total_migrate_scanned);
+        count_compact_events(COMPACTFREE_SCANNED, cc->total_free_scanned);
+
         trace_mm_compaction_end(start_pfn, cc->migrate_pfn,
                                 cc->free_pfn, end_pfn, sync, ret);
 
@@ -1645,6 +1648,8 @@ static enum compact_result compact_zone_order(struct zone *zone, int order,
         struct compact_control cc = {
                 .nr_freepages = 0,
                 .nr_migratepages = 0,
+                .total_migrate_scanned = 0,
+                .total_free_scanned = 0,
                 .order = order,
                 .gfp_mask = gfp_mask,
                 .zone = zone,
@@ -1757,6 +1762,8 @@ static void compact_node(int nid)
         struct zone *zone;
         struct compact_control cc = {
                 .order = -1,
+                .total_migrate_scanned = 0,
+                .total_free_scanned = 0,
                 .mode = MIGRATE_SYNC,
                 .ignore_skip_hint = true,
                 .whole_zone = true,
@@ -1883,6 +1890,8 @@ static void kcompactd_do_work(pg_data_t *pgdat)
         struct zone *zone;
         struct compact_control cc = {
                 .order = pgdat->kcompactd_max_order,
+                .total_migrate_scanned = 0,
+                .total_free_scanned = 0,
                 .classzone_idx = pgdat->kcompactd_classzone_idx,
                 .mode = MIGRATE_SYNC_LIGHT,
                 .ignore_skip_hint = true,
@@ -1891,7 +1900,7 @@ static void kcompactd_do_work(pg_data_t *pgdat)
         };
         trace_mm_compaction_kcompactd_wake(pgdat->node_id, cc.order,
                                                         cc.classzone_idx);
-        count_vm_event(KCOMPACTD_WAKE);
+        count_compact_event(KCOMPACTD_WAKE);
 
         for (zoneid = 0; zoneid <= cc.classzone_idx; zoneid++) {
                 int status;
@@ -1909,6 +1918,8 @@ static void kcompactd_do_work(pg_data_t *pgdat)
 
                 cc.nr_freepages = 0;
                 cc.nr_migratepages = 0;
+                cc.total_migrate_scanned = 0;
+                cc.total_free_scanned = 0;
                 cc.zone = zone;
                 INIT_LIST_HEAD(&cc.freepages);
                 INIT_LIST_HEAD(&cc.migratepages);
@@ -1927,6 +1938,11 @@ static void kcompactd_do_work(pg_data_t *pgdat)
                         defer_compaction(zone, cc.order);
                 }
 
+                count_compact_events(KCOMPACTD_MIGRATE_SCANNED,
+                                     cc.total_migrate_scanned);
+                count_compact_events(KCOMPACTD_FREE_SCANNED,
+                                     cc.total_free_scanned);
+
                 VM_BUG_ON(!list_empty(&cc.freepages));
                 VM_BUG_ON(!list_empty(&cc.migratepages));
         }