xpu: parallelize() not supported for PyTorch XPU backend

[dvrogozh]

With https://github.com/huggingface/transformers/releases/tag/v4.47.0.

Transforms gpt2, mt5, t5 and umt5 models don't support model parallelism when running on PyTorch XPU backend (on few gpu devices) as can be observed by running Transformers tests - see logs below.

Can model parallelism be supported for XPU backend?

• For GPT2 model, gpt2: enable model_parallel for xpu backend #35253
• For MT5 model
• For T5 model
• For UMT5 model

$ cat spec.py
import torch
DEVICE_NAME = 'xpu'
MANUAL_SEED_FN = torch.xpu.manual_seed
EMPTY_CACHE_FN = torch.xpu.empty_cache
DEVICE_COUNT_FN = torch.xpu.device_count

$ TRANSFORMERS_TEST_DEVICE_SPEC=spec.py python3 -m pytest -rsf tests/models/ -k "test_model_parallelization or test_model_parallel_equal_results"
<...>
FAILED tests/models/gpt2/test_modeling_gpt2.py::GPT2ModelTest::test_model_parallel_equal_results - ZeroDivisionError: division by zero
FAILED tests/models/gpt2/test_modeling_gpt2.py::GPT2ModelTest::test_model_parallelization - AssertionError: Torch not compiled with CUDA enabled
FAILED tests/models/mt5/test_modeling_mt5.py::MT5ModelTest::test_model_parallel_equal_results - ZeroDivisionError: division by zero
FAILED tests/models/mt5/test_modeling_mt5.py::MT5ModelTest::test_model_parallelization - AssertionError: Torch not compiled with CUDA enabled
FAILED tests/models/mt5/test_modeling_mt5.py::MT5EncoderOnlyModelTest::test_model_parallel_equal_results - ZeroDivisionError: division by zero
FAILED tests/models/mt5/test_modeling_mt5.py::MT5EncoderOnlyModelTest::test_model_parallelization - AssertionError: Torch not compiled with CUDA enabled
FAILED tests/models/t5/test_modeling_t5.py::T5ModelTest::test_model_parallel_equal_results - ZeroDivisionError: division by zero
FAILED tests/models/t5/test_modeling_t5.py::T5ModelTest::test_model_parallelization - AssertionError: Torch not compiled with CUDA enabled
FAILED tests/models/t5/test_modeling_t5.py::T5EncoderOnlyModelTest::test_model_parallel_equal_results - ZeroDivisionError: division by zero
FAILED tests/models/t5/test_modeling_t5.py::T5EncoderOnlyModelTest::test_model_parallelization - AssertionError: Torch not compiled with CUDA enabled
FAILED tests/models/umt5/test_modeling_umt5.py::UMT5EncoderOnlyModelTest::test_model_parallel_equal_results - AttributeError: 'UMT5EncoderModel' object has no attribute 'parallelize'
FAILED tests/models/umt5/test_modeling_umt5.py::UMT5EncoderOnlyModelTest::test_model_parallelization - AssertionError: Torch not compiled with CUDA enabled
=============================== 12 failed, 682 skipped, 76163 deselected, 5 warnings in 24.79s ================================

CC: @ArthurZucker @SunMarc

[dvrogozh]

As discussed in #35253 (review), parallelize() API is deprecated. As such it's not reasonable to add changes with new features (adding XPU backend support). Instead we've agreed to mark such tests as CUDA specific (#35253 (comment)). See the following PR for that:

• ci: mark model_parallel tests as cuda specific #35269