mm/compaction: more trace to understand when/why compaction start/finish

It is not well analyzed that when/why compaction start/finish or not.
With these new tracepoints, we can know much more about start/finish
reason of compaction.  I can find following bug with these tracepoint.

http://www.spinics.net/lists/linux-mm/msg81582.html

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 34 insertions, 4 deletions

diff --git a/mm/compaction.c b/mm/compaction.c
index b12df9fe10b4..b6ede459c1bb 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -41,6 +41,8 @@ static const char *const compaction_status_string[] = {
         "continue",
         "partial",
         "complete",
+        "no_suitable_page",
+        "not_suitable_zone",
 };
 #endif
 
@@ -1049,7 +1051,7 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
         return cc->nr_migratepages ? ISOLATE_SUCCESS : ISOLATE_NONE;
 }
 
-static int compact_finished(struct zone *zone, struct compact_control *cc,
+static int __compact_finished(struct zone *zone, struct compact_control *cc,
                             const int migratetype)
 {
         unsigned int order;
@@ -1104,7 +1106,20 @@ static int compact_finished(struct zone *zone, struct compact_control *cc,
                         return COMPACT_PARTIAL;
         }
 
-        return COMPACT_CONTINUE;
+        return COMPACT_NO_SUITABLE_PAGE;
+}
+
+static int compact_finished(struct zone *zone, struct compact_control *cc,
+                            const int migratetype)
+{
+        int ret;
+
+        ret = __compact_finished(zone, cc, migratetype);
+        trace_mm_compaction_finished(zone, cc->order, ret);
+        if (ret == COMPACT_NO_SUITABLE_PAGE)
+                ret = COMPACT_CONTINUE;
+
+        return ret;
 }
 
 /*
@@ -1114,7 +1129,7 @@ static int compact_finished(struct zone *zone, struct compact_control *cc,
  *   COMPACT_PARTIAL  - If the allocation would succeed without compaction
  *   COMPACT_CONTINUE - If compaction should run now
  */
-unsigned long compaction_suitable(struct zone *zone, int order,
+static unsigned long __compaction_suitable(struct zone *zone, int order,
                                         int alloc_flags, int classzone_idx)
 {
         int fragindex;
@@ -1158,11 +1173,24 @@ unsigned long compaction_suitable(struct zone *zone, int order,
          */
         fragindex = fragmentation_index(zone, order);
         if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
-                return COMPACT_SKIPPED;
+                return COMPACT_NOT_SUITABLE_ZONE;
 
         return COMPACT_CONTINUE;
 }
 
+unsigned long compaction_suitable(struct zone *zone, int order,
+                                        int alloc_flags, int classzone_idx)
+{
+        unsigned long ret;
+
+        ret = __compaction_suitable(zone, order, alloc_flags, classzone_idx);
+        trace_mm_compaction_suitable(zone, order, ret);
+        if (ret == COMPACT_NOT_SUITABLE_ZONE)
+                ret = COMPACT_SKIPPED;
+
+        return ret;
+}
+
 static int compact_zone(struct zone *zone, struct compact_control *cc)
 {
         int ret;
@@ -1376,6 +1404,8 @@ unsigned long try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
         if (!order || !may_enter_fs || !may_perform_io)
                 return COMPACT_SKIPPED;
 
+        trace_mm_compaction_try_to_compact_pages(order, gfp_mask, mode);
+
         /* Compact each zone in the list */
         for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx,
                                                                 ac->nodemask) {