DeepSpeed

b7b197ed - Derive the autocast test backend and scope the bf16 gate to NCCL (#8559)

Derive the autocast test backend and scope the bf16 gate to NCCL (#8559) ## Description `bf16_required_version_check()` (`tests/unit/util.py`) requires torch >= 1.10, **CUDA >= 11.0 and NCCL >= 2.10.3**. On the cpu accelerator, bf16 collectives run over gloo/ccl and none of those transport dependencies exist, so the check always returns False and **every bf16 test is skipped — about 40 call sites across 15 files**. `test_zero_autocast.py` is worse off: it **raises** instead of skipping, so each of its cases counts as a failure (24 on the multi-rank CPU run in #8381). This PR scopes the version floors inside the check itself: ```python if (cpu_accelerator and accelerator_pass) or (torch_version_available and cuda_version_available and nccl_version_available and accelerator_pass): return True ``` - **cpu**: only the accelerator's own bf16 support (`is_bf16_supported()`) is required — the torch/CUDA/NCCL floors are transport dependencies that gloo/ccl does not have - **every other accelerator** (cuda, npu, hpu, xpu, mlu, ...): evaluates the exact original floors; `cpu_accelerator` is False so the expression is bit-identical to before, and the npu/hpu/xpu exemption branches are untouched - `test_zero_autocast.py`: the bf16 gate goes back to the bare call every other caller uses, and skips instead of raising The hardcoded `init_distributed(dist_backend='nccl')` in the same test is deliberately left alone: it is a no-op (the harness already initialized the process group, `comm.py:838-839`), and deriving the backend per accelerator would change behavior on non-cuda accelerators (npu/hpu resolve to hccl etc.). The baseline `DDP(device_ids=[i])` pinning is left for a follow-up (#8399 fixed the same pattern elsewhere). ## Validation (executed on real hardware) - 20-core x86_64 CPU, torch 2.13.0+cpu, gloo backend - Direct call: `bf16_required_version_check()` on cpu returns `False` before, `True` after. Note: `CPU_Accelerator.is_bf16_supported()` is currently a stub that always returns True, so the cpu path does not gate on the hardware's bf16 instructions — giving it a real capability probe is left as a follow-up - Non-cpu equivalence: with `cpu_accelerator == False` the new expression reduces exactly to the original `A and C and N and P` - pre-commit (yapf / flake8 / check-torchdist / codespell) passes on both changed files Sibling PRs from the same series: #8397, #8398, #8399, #8407, #8409. Exposed by the `LOCAL_SIZE=4` multi-rank CPU run in #8381. Signed-off-by: Guokai Ma <guokai.ma@intel.com>