Add remote procedure call tunables to cinder

This allows us to override the default settings, which is useful for
large deployments or deploying a large number of cinder volumes at
once where backend response times are slowed down.

Change-Id: Ibd69473c8d66decea17daad5ce9a5f9e499d7779
Closes-Bug: #1617040

defaults/main.yml

@@ -158,6 +158,8 @@ cinder_iscsi_port: 3260
 
 ## Cinder RPC
 cinder_rpc_backend: rabbit
+cinder_rpc_executor_thread_pool_size: 64
+cinder_rpc_response_timeout: 60
 
 # (StrOpt) Method used to wipe old volumes (valid options are: none, zero,
 # shred)

releasenotes/notes/add-rpc-tunables-cfb2027b083ccf88.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - Deployers can now define the override ``cinder_rpc_executor_thread_pool_size``
+    which defaults to 64
+  - Deployers can now define the override ``cinder_rpc_response_timeout``
+    which defaults to 60

templates/cinder.conf.j2

@@ -49,6 +49,9 @@ backup_ceph_pool = {{ cinder_service_backup_ceph_pool }}
 
 ## RabbitMQ RPC
 rpc_backend = {{ cinder_rpc_backend }}
+executor_thread_pool_size = {{ cinder_rpc_executor_thread_pool_size }}
+rpc_response_timeout = {{ cinder_rpc_response_timeout }}
+
 transport_url = rabbit://{% for host in cinder_rabbitmq_servers.split(',') %}{{ cinder_rabbitmq_userid }}:{{ cinder_rabbitmq_password }}@{{ host }}:{{ cinder_rabbitmq_port }}{% if not loop.last %},{% else %}/{{ cinder_rabbitmq_vhost }}{% endif %}{% endfor %}
 
 ## Quota