diff --git a/playbooks/zuul-tox/post-system-logs.yaml b/playbooks/zuul-tox/post-system-logs.yaml
index 7a9da4821e..4374119140 100644
--- a/playbooks/zuul-tox/post-system-logs.yaml
+++ b/playbooks/zuul-tox/post-system-logs.yaml
@@ -1,5 +1,6 @@
 - hosts: all
+  roles:
+    - dstat-graph
   tasks:
-
     - name: Collect zookeeper logs
       shell: "cp /opt/zookeeper/logs/* {{ zuul_output_dir }}/logs/"
diff --git a/playbooks/zuul-tox/pre.yaml b/playbooks/zuul-tox/pre.yaml
index 45d213e97f..c8c1c65006 100644
--- a/playbooks/zuul-tox/pre.yaml
+++ b/playbooks/zuul-tox/pre.yaml
@@ -1,4 +1,6 @@
 - hosts: all
   roles:
+    - ensure-dstat-graph
+    - run-dstat
     - role: ensure-zookeeper
       zookeeper_use_tls: true
diff --git a/tox.ini b/tox.ini
index 889017fb3d..6c0e01db64 100644
--- a/tox.ini
+++ b/tox.ini
@@ -41,7 +41,7 @@ deps =
 docker =
   docker: zookeeper:3.4
 commands =
-  bash -c 'stestr run --slowest --concurrency=`python -c "import multiprocessing; print(int(multiprocessing.cpu_count()/2))"` {posargs}'
+  bash -c 'stestr run --slowest {posargs}'
 
 [testenv:bindep]
 # Do not install any requirements. We want this to be fast and work even if