LowVRAMPatch: change to two-phase visit

comfy/lora.py

@@ -475,16 +475,23 @@ def calculate_weight(patches, weight, key, intermediate_dtype=torch.float32, ori
 
     return weight
 
-def prefetch_prepared_value(value, allocate_buffer, stream):
+def prefetch_prepared_value(value, counter, destination, stream):
     if isinstance(value, torch.Tensor):
-        dest = allocate_buffer(comfy.memory_management.vram_aligned_size(value))
-        comfy.model_management.cast_to_gathered([value], dest, non_blocking=True, stream=stream)
+        size = comfy.memory_management.vram_aligned_size(value)
+        offset = counter[0]
+        counter[0] += size
+        if destination is None:
+            return value
+
+        dest = destination[offset:offset + size]
+        if stream is not None:
+            comfy.model_management.cast_to_gathered([value], dest, non_blocking=True, stream=stream)
         return comfy.memory_management.interpret_gathered_like([value], dest)[0]
     elif isinstance(value, weight_adapter.WeightAdapterBase):
-        return type(value)(value.loaded_keys, prefetch_prepared_value(value.weights, allocate_buffer, stream))
+        return type(value)(value.loaded_keys, prefetch_prepared_value(value.weights, counter, destination, stream))
     elif isinstance(value, tuple):
-        return tuple(prefetch_prepared_value(item, allocate_buffer, stream) for item in value)
+        return tuple(prefetch_prepared_value(item, counter, destination, stream) for item in value)
     elif isinstance(value, list):
-        return [prefetch_prepared_value(item, allocate_buffer, stream) for item in value]
+        return [prefetch_prepared_value(item, counter, destination, stream) for item in value]
 
     return value

comfy/model_patcher.py

@@ -124,9 +124,16 @@ class LowVramPatch:
         self.set_func = set_func
         self.prepared_patches = None
 
-    def prepare(self, allocate_buffer, stream):
+    def memory_required(self):
+        counter = [0]
+        for patch in self.patches[self.key]:
+            comfy.lora.prefetch_prepared_value(patch[1], counter, None, None)
+        return counter[0]
+
+    def prepare(self, destination, stream):
+        counter = [0]
         self.prepared_patches = [
-            (patch[0], comfy.lora.prefetch_prepared_value(patch[1], allocate_buffer, stream), patch[2], patch[3], patch[4])
+            (patch[0], comfy.lora.prefetch_prepared_value(patch[1], counter, destination, stream), patch[2], patch[3], patch[4])
             for patch in self.patches[self.key]
         ]
 

comfy/ops.py

@@ -203,7 +203,7 @@ def cast_modules_with_vbar(comfy_modules, dtype, device, bias_dtype, non_blockin
             lowvram_fn = getattr(s, param_key + "_lowvram_function", None)
             if lowvram_fn is not None:
                 ensure_offload_stream(s, cast_buffer_offset, False)
-                lowvram_fn.prepare(lambda size: get_cast_buffer(size), offload_stream)
+                lowvram_fn.prepare(get_cast_buffer(lowvram_fn.memory_required()), offload_stream)
 
         prefetch["xfer_dest"] = xfer_dest
         prefetch["cast_dest"] = cast_dest