[Metricbeat] Add new page statistics to system/memory metricset

metricbeat/docs/fields.asciidoc

@@ -31134,6 +31134,89 @@ type: long
 The percentage of used swap memory.
 
 
+type: scaled_float
+
+format: percent
+
+--
+
+[float]
+=== page_stats
+
+memory page statistics
+
+
+*`system.memory.page_stats.pgscan_kswapd.pages`*::
++
+--
+pages scanned by kswapd
+
+type: long
+
+format: number
+
+--
+
+*`system.memory.page_stats.pgscan_direct.pages`*::
++
+--
+pages scanned directly
+
+type: long
+
+format: number
+
+--
+
+*`system.memory.page_stats.pgfree.pages`*::
++
+--
+pages freed by the system
+
+type: long
+
+format: number
+
+--
+
+*`system.memory.page_stats.pgsteal_kswapd.pages`*::
++
+--
+number of pages reclaimed by kswapd
+
+type: long
+
+format: number
+
+--
+
+*`system.memory.page_stats.pgsteal_direct.pages`*::
++
+--
+number of pages reclaimed directly
+
+type: long
+
+format: number
+
+--
+
+*`system.memory.page_stats.direct_efficiency.pct`*::
++
+--
+direct reclaim efficiency percentage
+
+type: scaled_float
+
+format: percent
+
+--
+
+*`system.memory.page_stats.kswapd_efficiency.pct`*::
++
+--
+kswapd reclaim efficiency percentage
+
 type: scaled_float
 
 format: percent