dashboard: add runtime arena memory panel

Add "Runtime arena memory" panel to "Tarantool runtime overview"
section. It displays tnt_runtime_used default metric.

Rename "Lua runtime memory" panel to "Lua memory" to not confuse users
after adding"Runtime arena memory" panel. Update panel description so it
would be easier to understand the differences between two panels.

Closes #140

Author: DifferentialOrange

CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Added
 - Options to build static dashboards
+- Runtime arena memory panel
 
 ## Changed
 - Set default Prometheus job to `tarantool`

dashboard/panels/runtime.libsonnet

@@ -4,9 +4,10 @@ local common = import 'dashboard/panels/common.libsonnet';
   row:: common.row('Tarantool runtime overview'),
 
   lua_memory(
-    title='Lua runtime memory',
+    title='Lua memory',
     description=|||
-      Memory used for the Lua runtime.
+      Memory used for objects allocated with Lua
+      by using its internal mechanisms.
       Lua memory is bounded by 2 GB per instance. 
     |||,
     datasource_type=null,
@@ -20,7 +21,7 @@ local common = import 'dashboard/panels/common.libsonnet';
     datasource=datasource,
     format='bytes',
     labelY1='in bytes',
-    panel_width=12,
+    panel_width=8,
   ).addTarget(common.default_metric_target(
     datasource_type,
     'tnt_info_memory_lua',
@@ -29,6 +30,38 @@ local common = import 'dashboard/panels/common.libsonnet';
     measurement
   )),
 
+  runtime_memory(
+    title='Runtime arena memory',
+    description=|||
+      Memory used by runtime arena.
+      Runtime arena stores network buffers, tuples
+      created with box.tuple.new and other objects
+      allocated by application not covered by basic
+      Lua mechanisms (spaces data and indexes
+      are not included here, see memtx/vinyl arena).
+    |||,
+    datasource_type=null,
+    datasource=null,
+    policy=null,
+    measurement=null,
+    job=null,
+  ):: common.default_graph(
+    title=title,
+    description=description,
+    datasource=datasource,
+    format='bytes',
+    labelY1='in bytes',
+    legend_avg=false,
+    legend_max=false,
+    panel_width=8,
+  ).addTarget(common.default_metric_target(
+    datasource_type,
+    'tnt_runtime_used',
+    job,
+    policy,
+    measurement
+  )),
+
   memory_tx(
     title='Transactions memory',
     description=|||
@@ -48,7 +81,7 @@ local common = import 'dashboard/panels/common.libsonnet';
     datasource=datasource,
     format='bytes',
     labelY1='in bytes',
-    panel_width=12,
+    panel_width=8,
   ).addTarget(common.default_metric_target(
     datasource_type,
     'tnt_info_memory_tx',

dashboard/section.libsonnet

@@ -627,6 +627,14 @@ local tdg_tuples = import 'dashboard/panels/tdg/tuples.libsonnet';
       job=job,
     ),
 
+    runtime.runtime_memory(
+      datasource_type=datasource_type,
+      datasource=datasource,
+      policy=policy,
+      measurement=measurement,
+      job=job,
+    ),
+
     runtime.memory_tx(
       datasource_type=datasource_type,
       datasource=datasource,