Fix adaptive batch size to run on CPU (#4499)

* add warning instead of raising error

* fix unit test

Author: kprokofi

src/otx/backend/native/lightning/accelerators/xpu.py

@@ -60,5 +60,6 @@ def teardown(self) -> None:
 AcceleratorRegistry.register(
     XPUAccelerator.accelerator_name,
     XPUAccelerator,
+    override=True,
     description="Accelerator supports XPU devices",
 )

src/otx/backend/native/lightning/strategies/xpu_single.py

@@ -47,5 +47,6 @@ def __init__(
 StrategyRegistry.register(
     SingleXPUStrategy.strategy_name,
     SingleXPUStrategy,
+    override=True,
     description="Strategy that enables training on single XPU",
 )

src/otx/backend/native/tools/adaptive_bs/runner.py

@@ -42,8 +42,9 @@ def adapt_batch_size(
         callbacks (list[Callback] | Callback | None, optional): callbacks used during training. Defaults to None.
     """
     if not (is_cuda_available() or is_xpu_available()):
-        msg = "Adaptive batch size supports CUDA or XPU."
-        raise RuntimeError(msg)
+        msg = "Adaptive batch size supports only CUDA or XPU."
+        logger.warning(msg)
+        return
 
     engine.model.patch_optimizer_and_scheduler_for_adaptive_bs()
     default_bs = engine.datamodule.train_subset.batch_size

tests/unit/backend/native/tools/adaptive_bs/test_adaptive_bs_api.py

@@ -180,15 +180,18 @@ def test_adapt_batch_size_dist_sub_proc(
     assert int(mock_os.environ["ADAPTIVE_BS_FOR_DIST"]) == cur_bs
 
 
-def test_adapt_batch_size_no_accelerator(
+def test_adapt_batch_size_cpu(
     mock_is_cuda_available,
     mock_is_xpu_available,
     mock_engine,
     train_args,
+    mocker,
 ):
     mock_is_cuda_available.return_value = False
-    with pytest.raises(RuntimeError, match="Adaptive batch size supports CUDA or XPU."):
-        adapt_batch_size(mock_engine, **train_args)
+    mock_is_xpu_available.return_value = False
+    mock_logger = mocker.patch("otx.backend.native.tools.adaptive_bs.runner.logger")
+    adapt_batch_size(mock_engine, **train_args)
+    mock_logger.warning.assert_called_once_with("Adaptive batch size supports only CUDA or XPU.")
 
 
 def test_adjust_train_args(train_args):