diff --git a/nova/compute/manager.py b/nova/compute/manager.py
index ee0db485421a..d6938a146d05 100644
--- a/nova/compute/manager.py
+++ b/nova/compute/manager.py
@@ -512,7 +512,8 @@ class ComputeManager(manager.Manager):
         self.scheduler_client = scheduler_client.SchedulerClient()
         self._resource_tracker_dict = {}
         self.instance_events = InstanceEvents()
-        self._sync_power_pool = eventlet.GreenPool()
+        self._sync_power_pool = eventlet.GreenPool(
+            size=CONF.sync_power_state_pool_size)
         self._syncs_in_progress = {}
         self.send_instance_updates = CONF.scheduler_tracks_instance_changes
         if CONF.max_concurrent_builds != 0:
diff --git a/nova/conf/compute.py b/nova/conf/compute.py
index c1ad0e7f60a9..880454a30e61 100644
--- a/nova/conf/compute.py
+++ b/nova/conf/compute.py
@@ -375,6 +375,15 @@ Possible values:
 * If value is 0, then one attempt is made.
 * Any negative value is treated as 0.
 * For any value > 0, total attempts are (value + 1)
+"""),
+    cfg.IntOpt('sync_power_state_pool_size',
+               default=1000,
+               help="""
+Number of greenthreads available for use to sync power states.
+
+Possible values:
+
+* Any positive integer representing greenthreads count.
 """)
 ]
 
diff --git a/releasenotes/notes/sync_power_state_pool_size-81d2d142bffa055b.yaml b/releasenotes/notes/sync_power_state_pool_size-81d2d142bffa055b.yaml
new file mode 100644
index 000000000000..ce29759908cf
--- /dev/null
+++ b/releasenotes/notes/sync_power_state_pool_size-81d2d142bffa055b.yaml
@@ -0,0 +1,10 @@
+---
+other:
+  - New configuration option sync_power_state_pool_size
+    has been added to set the number of greenthreads available
+    for use to sync power states. Default value (1000) matches
+    the previous implicit default value provided by Greenpool.
+    This option can be used to reduce the number of concurrent requests
+    made to the hypervisor or system with real instance power states
+    for performance reasons.
+