diff --git a/teuthology/task/ceph_manager.py b/teuthology/task/ceph_manager.py
index 7f2ce9bfcf8..bd8285a26b7 100644
--- a/teuthology/task/ceph_manager.py
+++ b/teuthology/task/ceph_manager.py
@@ -266,7 +266,8 @@ class Thrasher:
             actions.append((self.in_osd, 1.7,))
         if len(self.dead_osds) > mindead:
             actions.append((self.revive_osd, 1.0,))
-        actions.append((self.primary_affinity, 1.0,))
+        if self.config.get('thrash_primary_affinity', True):
+            actions.append((self.primary_affinity, 1.0,))
         actions.append((self.grow_pool, self.config.get('chance_pgnum_grow', 0),))
         actions.append((self.fix_pgp_num, self.config.get('chance_pgpnum_fix', 0),))
         actions.append((self.test_pool_min_size, chance_test_min_size,))
diff --git a/teuthology/task/thrashosds.py b/teuthology/task/thrashosds.py
index 2bdd73d14fb..c5f26dcb740 100644
--- a/teuthology/task/thrashosds.py
+++ b/teuthology/task/thrashosds.py
@@ -63,6 +63,8 @@ def task(ctx, config):
     revive_timeout: (75) number of seconds to wait for an osd asok to
        appear after attempting to revive the osd
 
+    thrash_primary_affinity: (true) randomly adjust primary-affinity
+
     chance_pgnum_grow: (0) chance to increase a pool's size
     chance_pgpnum_fix: (0) chance to adjust pgpnum to pg for a pool
     pool_grow_by: (10) amount to increase pgnum by