[Feature]: FP8 Quantization Support for DiT (#1034)

Signed-off-by: lishunyang <lishunyang12@163.com>
Signed-off-by: SYLAR <125541396+lishunyang12@users.noreply.github.com>

vllm_omni/diffusion/quantization/fp8.py

@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+"""FP8 quantization config for diffusion transformers."""
+
+from vllm.model_executor.layers.quantization.fp8 import Fp8Config
+
+from .base import DiffusionQuantizationConfig
+
+
+class DiffusionFp8Config(DiffusionQuantizationConfig):
+    """FP8 quantization config optimized for diffusion transformers.
+
+    Uses dynamic activation scaling (no calibration dataset needed) and
+    online weight quantization from BF16/FP16 checkpoints.
+
+    Device Compatibility:
+        - Turing (SM 75+): Weight-only FP8 via Marlin kernel
+        - Ada/Hopper (SM 89+): Full W8A8 FP8 with native hardware support
+
+    The kernel selection is automatic based on GPU capability.
+
+    Args:
+        activation_scheme: Activation quantization scheme.
+            - "dynamic": Per-token dynamic scaling (default, no calibration)
+            - "static": Single per-tensor scale (requires calibration)
+        weight_block_size: Block size for block-wise weight quantization.
+            Format: [block_n, block_k]. If None, uses per-tensor scaling.
+        ignored_layers: List of layer name patterns to skip quantization.
+    """
+
+    # Tight coupling with vLLM's Fp8Config - delegates get_name() and get_min_capability()
+    quant_config_cls = Fp8Config
+
+    def __init__(
+        self,
+        activation_scheme: str = "dynamic",
+        weight_block_size: list[int] | None = None,
+        ignored_layers: list[str] | None = None,
+    ):
+        self.activation_scheme = activation_scheme
+        self.weight_block_size = weight_block_size
+        self.ignored_layers = ignored_layers or []
+
+        # Create underlying vLLM FP8 config
+        self._vllm_config = Fp8Config(
+            is_checkpoint_fp8_serialized=False,  # Online quantization from BF16
+            activation_scheme=activation_scheme,
+            weight_block_size=weight_block_size,
+            ignored_layers=ignored_layers,
+        )