diff -r b4d0bdb52694 -r 909e559f4b41 configs/ruby/Ruby.py
--- a/configs/ruby/Ruby.py	Wed Aug 01 17:07:34 2012 -0500
+++ b/configs/ruby/Ruby.py	Thu Aug 02 15:04:34 2012 -0400
@@ -51,8 +51,9 @@
     # ruby network options
     parser.add_option("--topology", type="string", default="Crossbar",
                  help="check src/mem/ruby/network/topologies for complete set")
-    parser.add_option("--mesh-rows", type="int", default=1,
-                      help="the number of rows in the mesh topology")
+    parser.add_option("--mesh-rows", type="int", default=0,
+                      help="the number of rows in the mesh topology" \
+                      "default = sqrt(num_cpus)")
     parser.add_option("--garnet-network", type="string", default=None,
                       help="'fixed'|'flexible'")
     parser.add_option("--network-fault-model", action="store_true", default=False,
diff -r b4d0bdb52694 -r 909e559f4b41 configs/topologies/Mesh.py
--- a/configs/topologies/Mesh.py	Wed Aug 01 17:07:34 2012 -0500
+++ b/configs/topologies/Mesh.py	Thu Aug 02 15:04:34 2012 -0400
@@ -26,6 +26,7 @@
 #
 # Authors: Brad Beckmann
 
+import math
 from m5.params import *
 from m5.objects import *
 
@@ -43,7 +44,10 @@
         nodes = self.nodes
 
         num_routers = options.num_cpus
-        num_rows = options.mesh_rows
+        if options.mesh_rows == 0:
+            num_rows = int(math.sqrt(num_routers))
+        else:
+            num_rows = options.mesh_rows
 
         # There must be an evenly divisible number of cntrls to routers
         # Also, obviously the number or rows must be <= the number of routers
diff -r b4d0bdb52694 -r 909e559f4b41 configs/topologies/MeshDirCorners.py
--- a/configs/topologies/MeshDirCorners.py	Wed Aug 01 17:07:34 2012 -0500
+++ b/configs/topologies/MeshDirCorners.py	Thu Aug 02 15:04:34 2012 -0400
@@ -26,6 +26,7 @@
 #
 # Authors: Brad Beckmann
 
+import math
 from m5.params import *
 from m5.objects import *
 
@@ -46,7 +47,10 @@
         nodes = self.nodes
 
         num_routers = options.num_cpus
-        num_rows = options.mesh_rows
+        if options.mesh_rows == 0:
+            num_rows = int(math.sqrt(num_routers))
+        else:
+            num_rows = options.mesh_rows
 
         # First determine which nodes are cache cntrls vs. dirs vs. dma
         cache_nodes = []