vllm.platforms.zen_cpu ¶

class ZenCpuPlatform(CpuPlatform):
    """CPU platform with AMD Zen (ZenDNN/zentorch) optimizations.

    Model-load time (dispatch_cpu_unquantized_gemm in layers/utils.py):
      - Routes linear ops to zentorch_linear_unary.
      - When VLLM_ZENTORCH_WEIGHT_PREPACK=1 (default), eagerly prepacks
        weights via zentorch_weight_prepack_for_linear.
    """

    device_name: str = "cpu"
    device_type: str = "cpu"

    def is_zen_cpu(self) -> bool:
        # is_cpu() also returns True for this platform (inherited from CpuPlatform).
        return True

    @classmethod
    def check_and_update_config(cls, vllm_config: "VllmConfig") -> None:
        super().check_and_update_config(vllm_config)
        cls._apply_pytorch_backports()

    @classmethod
    def _apply_pytorch_backports(cls):
        """Backport PyTorch mainline fixes missing in 2.10.

        PyTorch 2.10 has a bug in FxGraphCachePickler.dumps that doesn't
        catch ValueError, causing torch.compile cache misses. Remove this
        once we drop PyTorch 2.10 support. PT mainline already has this fix.
        """
        if not is_torch_equal_or_newer("2.10.0") or is_torch_equal_or_newer("2.11.0"):
            return

        cls._patch_fxgraphcache_pickle()

    @classmethod
    def _patch_fxgraphcache_pickle(cls):
        """Backport mainline ValueError fix to FxGraphCachePickler.dumps()."""
        from torch._inductor.codecache import BypassFxGraphCache, FxGraphCachePickler

        original_dumps = FxGraphCachePickler.dumps
        if hasattr(original_dumps, "_zen_patched"):
            return

        def patched_dumps(self, obj):
            try:
                return original_dumps(self, obj)
            except ValueError as e:
                raise BypassFxGraphCache("Failed to pickle cache key") from e

        patched_dumps._zen_patched = True  # type: ignore[attr-defined]
        FxGraphCachePickler.dumps = patched_dumps
        logger.info("[zen_cpu] Patched FxGraphCachePickler.dumps (ValueError fix)")