Don't enable Vulkan validation

master/master.cfg

@@ -1004,8 +1004,12 @@ def add_env_setup_step(factory, builder_type, enable_ccache=False):
     # specification. This should not be enabled in production due to the overhead,
     # but we want to catch any changes in driver behaviour and/or spurious errors that
     # may be hard to find (but easy to fix if the right error messages are present)
-    if builder_type.has_nvidia() and builder_type.handles_vulkan():
-        env['VK_INSTANCE_LAYERS'] = "VK_LAYER_KHRONOS_validation"
+    #
+    # Nov 7 2024: this validation layer is not resilient to running tests in parallel,
+    # which we do, so we're not going to enable it for now
+    #
+    # if builder_type.has_nvidia() and builder_type.handles_vulkan():
+    #     env['VK_INSTANCE_LAYERS'] = "VK_LAYER_KHRONOS_validation"
 
     if builder_type.os == 'osx':
         # Environment variable for turning on Metal API validation