Provide option to reduce CPU RAM usage in Group Offload

src/diffusers/hooks/group_offloading.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from contextlib import nullcontext
+from contextlib import contextmanager, nullcontext
 from typing import Dict, List, Optional, Set, Tuple
 
 import torch
@@ -56,23 +56,58 @@ def __init__(
         buffers: Optional[List[torch.Tensor]] = None,
         non_blocking: bool = False,
         stream: Optional[torch.cuda.Stream] = None,
-        cpu_param_dict: Optional[Dict[torch.nn.Parameter, torch.Tensor]] = None,
+        low_cpu_mem_usage=False,
         onload_self: bool = True,
     ) -> None:
         self.modules = modules
         self.offload_device = offload_device
         self.onload_device = onload_device
         self.offload_leader = offload_leader
         self.onload_leader = onload_leader
-        self.parameters = parameters
-        self.buffers = buffers
+        self.parameters = parameters or []
+        self.buffers = buffers or []
         self.non_blocking = non_blocking or stream is not None
         self.stream = stream
-        self.cpu_param_dict = cpu_param_dict
         self.onload_self = onload_self
+        self.low_cpu_mem_usage = low_cpu_mem_usage
 
-        if self.stream is not None and self.cpu_param_dict is None:
-            raise ValueError("cpu_param_dict must be provided when using stream for data transfer.")
+        self.cpu_param_dict = self._init_cpu_param_dict()
+
+    def _init_cpu_param_dict(self):
+        cpu_param_dict = {}
+        if self.stream is None:
+            return cpu_param_dict
+
+        for module in self.modules:
+            for param in module.parameters():
+                cpu_param_dict[param] = param.data.cpu() if self.low_cpu_mem_usage else param.data.cpu().pin_memory()
+            for buffer in module.buffers():
+                cpu_param_dict[buffer] = (
+                    buffer.data.cpu() if self.low_cpu_mem_usage else buffer.data.cpu().pin_memory()
+                )
+
+        for param in self.parameters:
+            cpu_param_dict[param] = param.data.cpu() if self.low_cpu_mem_usage else param.data.cpu().pin_memory()
+
+        for buffer in self.buffers:
+            cpu_param_dict[buffer] = buffer.data.cpu() if self.low_cpu_mem_usage else buffer.data.cpu().pin_memory()
+
+        return cpu_param_dict
+
+    @contextmanager
+    def _pinned_memory_tensors(self):
+        pinned_dict = {}
+        try:
+            for param, tensor in self.cpu_param_dict.items():
+                if not tensor.is_pinned():
+                    pinned_dict[param] = tensor.pin_memory()
+                else:
+                    pinned_dict[param] = tensor
+
+            yield pinned_dict
+
+        finally:
+            pinned_dict = None
 
     def onload_(self):
         r"""Onloads the group of modules to the onload_device."""
@@ -82,15 +117,30 @@ def onload_(self):
             self.stream.synchronize()
 
         with context:
-            for group_module in self.modules:
-                for param in group_module.parameters():
-                    param.data = param.data.to(self.onload_device, non_blocking=self.non_blocking)
-                for buffer in group_module.buffers():
-                    buffer.data = buffer.data.to(self.onload_device, non_blocking=self.non_blocking)
-            if self.parameters is not None:
+            if self.stream is not None:
+                with self._pinned_memory_tensors() as pinned_memory:
+                    for group_module in self.modules:
+                        for param in group_module.parameters():
+                            param.data = pinned_memory[param].to(self.onload_device, non_blocking=self.non_blocking)
+                        for buffer in group_module.buffers():
+                            buffer.data = pinned_memory[buffer].to(self.onload_device, non_blocking=self.non_blocking)
+
+                    for param in self.parameters:
+                        param.data = pinned_memory[param].to(self.onload_device, non_blocking=self.non_blocking)
+
+                    for buffer in self.buffers:
+                        buffer.data = pinned_memory[buffer].to(self.onload_device, non_blocking=self.non_blocking)
+
+            else:
+                for group_module in self.modules:
+                    for param in group_module.parameters():
+                        param.data = param.data.to(self.onload_device, non_blocking=self.non_blocking)
+                    for buffer in group_module.buffers():
+                        buffer.data = buffer.data.to(self.onload_device, non_blocking=self.non_blocking)
+
                 for param in self.parameters:
                     param.data = param.data.to(self.onload_device, non_blocking=self.non_blocking)
-            if self.buffers is not None:
+
                 for buffer in self.buffers:
                     buffer.data = buffer.data.to(self.onload_device, non_blocking=self.non_blocking)
 
@@ -101,21 +151,18 @@ def offload_(self):
             for group_module in self.modules:
                 for param in group_module.parameters():
                     param.data = self.cpu_param_dict[param]
-            if self.parameters is not None:
-                for param in self.parameters:
-                    param.data = self.cpu_param_dict[param]
-            if self.buffers is not None:
-                for buffer in self.buffers:
-                    buffer.data = self.cpu_param_dict[buffer]
+            for param in self.parameters:
+                param.data = self.cpu_param_dict[param]
+            for buffer in self.buffers:
+                buffer.data = self.cpu_param_dict[buffer]
+
         else:
             for group_module in self.modules:
                 group_module.to(self.offload_device, non_blocking=self.non_blocking)
-            if self.parameters is not None:
-                for param in self.parameters:
-                    param.data = param.data.to(self.offload_device, non_blocking=self.non_blocking)
-            if self.buffers is not None:
-                for buffer in self.buffers:
-                    buffer.data = buffer.data.to(self.offload_device, non_blocking=self.non_blocking)
+            for param in self.parameters:
+                param.data = param.data.to(self.offload_device, non_blocking=self.non_blocking)
+            for buffer in self.buffers:
+                buffer.data = buffer.data.to(self.offload_device, non_blocking=self.non_blocking)
 
 
 class GroupOffloadingHook(ModelHook):
@@ -284,6 +331,7 @@ def apply_group_offloading(
     num_blocks_per_group: Optional[int] = None,
     non_blocking: bool = False,
     use_stream: bool = False,
+    low_cpu_mem_usage=False,
 ) -> None:
     r"""
     Applies group offloading to the internal layers of a torch.nn.Module. To understand what group offloading is, and
@@ -365,10 +413,12 @@ def apply_group_offloading(
             raise ValueError("num_blocks_per_group must be provided when using offload_type='block_level'.")
 
         _apply_group_offloading_block_level(
-            module, num_blocks_per_group, offload_device, onload_device, non_blocking, stream
+            module, num_blocks_per_group, offload_device, onload_device, non_blocking, stream, low_cpu_mem_usage
         )
     elif offload_type == "leaf_level":
-        _apply_group_offloading_leaf_level(module, offload_device, onload_device, non_blocking, stream)
+        _apply_group_offloading_leaf_level(
+            module, offload_device, onload_device, non_blocking, stream, low_cpu_mem_usage
+        )
     else:
         raise ValueError(f"Unsupported offload_type: {offload_type}")
 
@@ -380,6 +430,7 @@ def _apply_group_offloading_block_level(
     onload_device: torch.device,
     non_blocking: bool,
     stream: Optional[torch.cuda.Stream] = None,
+    low_cpu_mem_usage: bool = False,
 ) -> None:
     r"""
     This function applies offloading to groups of torch.nn.ModuleList or torch.nn.Sequential blocks. In comparison to
@@ -400,11 +451,6 @@ def _apply_group_offloading_block_level(
             for overlapping computation and data transfer.
     """
 
-    # Create a pinned CPU parameter dict for async data transfer if streams are to be used
-    cpu_param_dict = None
-    if stream is not None:
-        cpu_param_dict = _get_pinned_cpu_param_dict(module)
-
     # Create module groups for ModuleList and Sequential blocks
     modules_with_group_offloading = set()
     unmatched_modules = []
@@ -425,7 +471,7 @@ def _apply_group_offloading_block_level(
                 onload_leader=current_modules[0],
                 non_blocking=non_blocking,
                 stream=stream,
-                cpu_param_dict=cpu_param_dict,
+                low_cpu_mem_usage=low_cpu_mem_usage,
                 onload_self=stream is None,
             )
             matched_module_groups.append(group)
@@ -462,7 +508,6 @@ def _apply_group_offloading_block_level(
         buffers=buffers,
         non_blocking=False,
         stream=None,
-        cpu_param_dict=None,
         onload_self=True,
     )
     next_group = matched_module_groups[0] if len(matched_module_groups) > 0 else None
@@ -475,6 +520,7 @@ def _apply_group_offloading_leaf_level(
     onload_device: torch.device,
     non_blocking: bool,
     stream: Optional[torch.cuda.Stream] = None,
+    low_cpu_mem_usage: bool = False,
 ) -> None:
     r"""
     This function applies offloading to groups of leaf modules in a torch.nn.Module. This method has minimal memory
@@ -497,11 +543,6 @@ def _apply_group_offloading_leaf_level(
             for overlapping computation and data transfer.
     """
 
-    # Create a pinned CPU parameter dict for async data transfer if streams are to be used
-    cpu_param_dict = None
-    if stream is not None:
-        cpu_param_dict = _get_pinned_cpu_param_dict(module)
-
     # Create module groups for leaf modules and apply group offloading hooks
     modules_with_group_offloading = set()
     for name, submodule in module.named_modules():
@@ -515,7 +556,7 @@ def _apply_group_offloading_leaf_level(
             onload_leader=submodule,
             non_blocking=non_blocking,
             stream=stream,
-            cpu_param_dict=cpu_param_dict,
+            low_cpu_mem_usage=low_cpu_mem_usage,
             onload_self=True,
         )
         _apply_group_offloading_hook(submodule, group, None)
@@ -560,7 +601,7 @@ def _apply_group_offloading_leaf_level(
             buffers=buffers,
             non_blocking=non_blocking,
             stream=stream,
-            cpu_param_dict=cpu_param_dict,
+            low_cpu_mem_usage=low_cpu_mem_usage,
             onload_self=True,
         )
         _apply_group_offloading_hook(parent_module, group, None)
@@ -579,7 +620,7 @@ def _apply_group_offloading_leaf_level(
             buffers=None,
             non_blocking=False,
             stream=None,
-            cpu_param_dict=None,
+            low_cpu_mem_usage=low_cpu_mem_usage,
             onload_self=True,
         )
         _apply_lazy_group_offloading_hook(module, unmatched_group, None)
@@ -616,17 +657,6 @@ def _apply_lazy_group_offloading_hook(
     registry.register_hook(lazy_prefetch_hook, _LAZY_PREFETCH_GROUP_OFFLOADING)
 
 
-def _get_pinned_cpu_param_dict(module: torch.nn.Module) -> Dict[torch.nn.Parameter, torch.Tensor]:
-    cpu_param_dict = {}
-    for param in module.parameters():
-        param.data = param.data.cpu().pin_memory()
-        cpu_param_dict[param] = param.data
-    for buffer in module.buffers():
-        buffer.data = buffer.data.cpu().pin_memory()
-        cpu_param_dict[buffer] = buffer.data
-    return cpu_param_dict
-
-
 def _gather_parameters_with_no_group_offloading_parent(
     module: torch.nn.Module, modules_with_group_offloading: Set[str]
 ) -> List[torch.nn.Parameter]:

src/diffusers/models/modeling_utils.py

@@ -546,6 +546,7 @@ def enable_group_offload(
         num_blocks_per_group: Optional[int] = None,
         non_blocking: bool = False,
         use_stream: bool = False,
+        low_cpu_mem_usage=False,
     ) -> None:
         r"""
         Activates group offloading for the current model.
@@ -584,7 +585,14 @@ def enable_group_offload(
                 f"open an issue at https://github.com/huggingface/diffusers/issues."
             )
         apply_group_offloading(
-            self, onload_device, offload_device, offload_type, num_blocks_per_group, non_blocking, use_stream
+            self,
+            onload_device,
+            offload_device,
+            offload_type,
+            num_blocks_per_group,
+            non_blocking,
+            use_stream,
+            low_cpu_mem_usage=low_cpu_mem_usage,
         )
 
     def save_pretrained(