Make the number of workers for account, container and object servers a multiplier of the number of CPUs, and default to a sensible setting per recommendations in http://docs.openstack.org/developer/swift/deployment_guide.html#general-service-tuning

config.yaml

@@ -49,4 +49,9 @@ options:
     default: 6002
     type: int
     description: Listening port of the swift-account-server.
-
+  worker-multiplier:
+    default: 1
+    type: int
+    description: |
+      The CPU multiplier to use when configuring worker processes for the
+      account, container and object server processes.

hooks/swift_storage_context.py

@@ -61,10 +61,13 @@ class SwiftStorageServerContext(OSContextGenerator):
     interfaces = []
 
     def __call__(self):
+        import psutil
+        multiplier = config('worker-multiplier') or 1
         ctxt = {
             'local_ip': unit_private_ip(),
             'account_server_port': config('account-server-port'),
             'container_server_port': config('container-server-port'),
             'object_server_port': config('object-server-port'),
+            'workers': psutil.NUM_CPUS * multiplier,
         }
         return ctxt

hooks/swift_storage_utils.py

@@ -48,7 +48,7 @@ from charmhelpers.contrib.openstack import (
 
 PACKAGES = [
     'swift', 'swift-account', 'swift-container', 'swift-object',
-    'xfsprogs', 'gdisk', 'lvm2', 'python-jinja2',
+    'xfsprogs', 'gdisk', 'lvm2', 'python-jinja2', 'python-psutil',
 ]
 
 TEMPLATES = 'templates/'

templates/account-server.conf

@@ -1,7 +1,7 @@
 [DEFAULT]
 bind_ip = 0.0.0.0
 bind_port = {{ account_server_port }}
-workers = 2
+workers = {{ workers }}
 
 [pipeline:main]
 pipeline = recon account-server

templates/container-server.conf

@@ -1,7 +1,7 @@
 [DEFAULT]
 bind_ip = 0.0.0.0
 bind_port = {{ container_server_port }}
-workers = 2
+workers = {{ workers }}
 
 [pipeline:main]
 pipeline = recon container-server

templates/object-server.conf

@@ -1,7 +1,7 @@
 [DEFAULT]
 bind_ip = 0.0.0.0
 bind_port = {{ object_server_port }}
-workers = 2
+workers = {{ workers }}
 
 [pipeline:main]
 pipeline = recon object-server