diff --git a/README.md b/README.md
index 267752b..53e62bd 100644
--- a/README.md
+++ b/README.md
@@ -183,9 +183,16 @@ class CommentController < ApplicationController
 end
 ```
 
-Once you instrument an action, `librato-rails` will start reporting a set of metrics specific to that action including # of requests, total time used per request, and db and view time used per request.
+Once you instrument an action, `librato-rails` will start reporting a set of metrics specific to that action including:
 
-Action instrumentation metrics are named following the format `rails.action.<controller>.<action>.<format>.*`.
+* rails.action.request.total     (# of requests)
+* rails.action.request.slow      (requests >= 200ms to produce)
+* rails.action.request.exceptions
+* rails.action.request.time      (total time spent in action)
+* rails.action.request.time.db   (db interaction time)
+* rails.action.request.time.view (view rendering time)
+
+Each instrumented action will appear as a source for the `rails.action.*` metrics, for example `mycontroller.action.html`.
 
 IMPORTANT NOTE: Metrics from `instrument_action` take into account all time spent in the ActionController stack for that action, including before/after filters and any global processing. They are _not_ equivalent to using a `Librato.timing` block inside the method body.
 
diff --git a/lib/librato/rails/subscribers/controller.rb b/lib/librato/rails/subscribers/controller.rb
index b9284ca..cf8f708 100644
--- a/lib/librato/rails/subscribers/controller.rb
+++ b/lib/librato/rails/subscribers/controller.rb
@@ -56,17 +56,18 @@ def self.watch_controller_action(controller, action)
         end # end group
 
         if @watches && @watches.index("#{controller}##{action}")
-          page_key = "#{controller}.#{action}.#{format}"
-          collector.group "rails.action.#{page_key}" do |r|
+          source = "#{controller}.#{action}.#{format}"
+          collector.group 'rails.action.request' do |r|
 
-            r.increment 'total'
-            r.timing    'time', event.duration
+            r.increment 'total', source: source
+            r.increment 'slow', source: source if event.duration > 200.0
+            r.timing    'time', event.duration, source: source
 
             if exception
-              r.increment 'exceptions'
+              r.increment 'exceptions', source: source
             else
-              r.timing 'time.db', event.payload[:db_runtime] || 0
-              r.timing 'time.view', event.payload[:view_runtime] || 0
+              r.timing 'time.db', event.payload[:db_runtime] || 0, source: source
+              r.timing 'time.view', event.payload[:view_runtime] || 0, source: source
             end
 
           end
diff --git a/test/integration/instrument_action_test.rb b/test/integration/instrument_action_test.rb
index 65a56c3..c3a80fa 100644
--- a/test/integration/instrument_action_test.rb
+++ b/test/integration/instrument_action_test.rb
@@ -8,14 +8,15 @@ class InstrumentActionTest < ActiveSupport::IntegrationCase
     # puts aggregate.instance_variable_get(:@cache).queued.inspect
     # puts counters.instance_variable_get(:@cache).inspect
 
-    base = 'rails.action.InstrumentActionController.inst.html'
+    source = 'InstrumentActionController.inst.html'
 
+    base = 'rails.action.request'
     timings = %w{time time.db time.view}
     timings.each do |t|
-      assert_equal 1, aggregate["#{base}.#{t}"][:count]
+      assert_equal 1, aggregate.fetch("#{base}.#{t}", source: source)[:count]
     end
 
-    assert_equal 1, counters["#{base}.total"]
+    assert_equal 1, counters.fetch("#{base}.total", source: source)
   end
 
 end