filter proxies in remat, improve tests

thunder/core/rematerialization.py

@@ -192,7 +192,9 @@ def apply_rematerialization_for_consumer(
     _, leaves = bsym_list_to_dag(list(new_subsymbols))
     new_subsymbols = toposort_bsym_dag(leaves, TOPOSORT_ORDER.BOTTOM_UP)
     proxy_order = order_proxies(new_subsymbols)
-    new_consumer_args = tuple(sorted(new_consumer_args, key=lambda x: proxy_order[x.name]))
+    new_consumer_args = tuple(
+        sorted((a for a in new_consumer_args if a.name in proxy_order), key=lambda x: proxy_order[x.name])
+    )
     new_consumer = replace(consumer, args=new_consumer_args, subsymbols=new_subsymbols)
     return new_consumer
 

thunder/tests/test_grad.py

@@ -1813,8 +1813,8 @@ def forward(self, *args):
     # the rematerialization pass moved all(?) recomputation to the front,
     # making the peak mem about 46MB.
     # With checkpointing as coded in the model and recomputation where the
-    # values are used, we get about 12MB, so we put the barrier at 16MB
-    assert mem_max - mem_base < 16 * 2**20
+    # values are used, we get about 12-20MB, so we put the barrier at 24MB
+    assert mem_max - mem_base < 24 * 2**20
 
 
 def test_inconsistent_output_length_grad_transform():
@@ -1906,6 +1906,9 @@ def forward(x):
 
 @pytest.mark.parametrize("device", ("cuda", "cpu"))
 def test_backward_recomputation_decomposed_ops(device):
+    if device == "cuda" and not torch.cuda.is_available():
+        pytest.skip("CUDA is not available")
+
     def fn(a):
         return torch.nn.functional.gelu(a)