add test for active defrag

tests/unit/memefficiency.tcl

@@ -35,3 +35,48 @@ start_server {tags {"memefficiency"}} {
         }
     }
 }
+
+start_server {tags {"defrag"}} {
+    if {[string match {*jemalloc*} [s mem_allocator]]} {
+        test "Actove defrag" {
+            r config set activedefrag no
+            r config set active-defrag-threshold-lower 5
+            r config set active-defrag-ignore-bytes 2mb
+            r config set maxmemory 100mb
+            r config set maxmemory-policy allkeys-lru
+            r debug populate 700000 asdf 150
+            r debug populate 170000 asdf 300
+            set frag [s mem_fragmentation_ratio]
+            assert {$frag >= 1.7}
+            r config set activedefrag yes
+            after 1500 ;# active defrag tests the status once a second.
+            set hits [s active_defrag_hits]
+
+            # wait for the active defrag to stop working
+            set tries 0
+            while { True } {
+                incr tries
+                after 500
+                set prev_hits $hits
+                set hits [s active_defrag_hits]
+                if {$hits == $prev_hits} {
+                    break
+                }
+                assert {$tries < 100}
+            }
+
+            # TODO: we need to expose more accurate fragmentation info
+            # i.e. the allocator used and active pages
+            # instead we currently look at RSS so we need to ask for purge
+            r memory purge
+
+            # test the the fragmentation is lower and that the defragger stopped working
+            set frag [s mem_fragmentation_ratio]
+            assert {$frag < 1.4}
+            set misses [s active_defrag_misses]
+            after 500
+            set misses2 [s active_defrag_misses]
+            assert {$misses2 == $misses}
+        }
+    }
+}