[Feature] Add VLLM_USE_DEEP_GEMM_E8M0 Env to Control E8M0 Scale (vllm-project#21968)

Signed-off-by: yewentao256 <[email protected]>

Author: yewentao256

tests/kernels/moe/test_block_fp8.py

@@ -16,7 +16,7 @@
     fused_topk, modular_triton_fused_moe)
 from vllm.platforms import current_platform
 from vllm.utils import has_deep_gemm
-from vllm.utils.deep_gemm import is_blackwell_deep_gemm_used
+from vllm.utils.deep_gemm import is_blackwell_deep_gemm_e8m0_used
 
 dg_available = has_deep_gemm()
 
@@ -224,7 +224,8 @@ def test_w8a8_block_fp8_fused_moe(M, N, K, E, topk, block_size, dtype, seed,
 @pytest.mark.parametrize("topk", TOP_KS)
 @pytest.mark.parametrize("seed", SEEDS)
 @pytest.mark.skipif(not dg_available, reason="DeepGemm kernels not available.")
-@pytest.mark.skipif(is_blackwell_deep_gemm_used(), reason="Not E8M0 scale MOE")
+@pytest.mark.skipif(is_blackwell_deep_gemm_e8m0_used(),
+                    reason="Not E8M0 scale MOE")
 @torch.inference_mode()
 def test_w8a8_block_fp8_deep_gemm_fused_moe(M, N, K, E, topk, seed,
                                             monkeypatch):

tests/kernels/moe/test_deepep_deepgemm_moe.py

@@ -20,7 +20,7 @@
     FusedMoEModularKernel)
 from vllm.platforms import current_platform
 from vllm.utils import has_deep_ep, has_deep_gemm
-from vllm.utils.deep_gemm import (is_blackwell_deep_gemm_used,
+from vllm.utils.deep_gemm import (is_blackwell_deep_gemm_e8m0_used,
                                   is_deep_gemm_supported)
 
 from .parallel_utils import ProcessGroupInfo, parallel_launch
@@ -370,7 +370,7 @@ def _test_deepep_deepgemm_moe(
 @pytest.mark.parametrize("world_dp_size", [(2, 1)])
 @requires_deep_ep
 @requires_deep_gemm
-@pytest.mark.skipif(is_blackwell_deep_gemm_used(),
+@pytest.mark.skipif(is_blackwell_deep_gemm_e8m0_used(),
                     reason="Skipping test for Blackwell DeepGEMM")
 def test_ht_deepep_deepgemm_moe(mnk: tuple[int, int, int], num_experts: int,
                                 topk: int, world_dp_size: tuple[int, int]):
@@ -427,7 +427,7 @@ def test_ht_deepep_deepgemm_moe(mnk: tuple[int, int, int], num_experts: int,
 @pytest.mark.parametrize("world_dp_size", [(2, 1)])
 @requires_deep_ep
 @requires_deep_gemm
-@pytest.mark.skipif(is_blackwell_deep_gemm_used(),
+@pytest.mark.skipif(is_blackwell_deep_gemm_e8m0_used(),
                     reason="Skipping test for Blackwell DeepGEMM")
 def test_ll_deepep_deepgemm_moe(
     mnk: tuple[int, int, int],

vllm/envs.py

@@ -127,6 +127,7 @@
     VLLM_TPU_MOST_MODEL_LEN: Optional[int] = None
     VLLM_TPU_USING_PATHWAYS: bool = False
     VLLM_USE_DEEP_GEMM: bool = False
+    VLLM_USE_DEEP_GEMM_E8M0: bool = True
     VLLM_SKIP_DEEP_GEMM_WARMUP: bool = False
     VLLM_USE_FLASHINFER_MOE_FP8: bool = False
     VLLM_USE_FLASHINFER_MOE_FP4: bool = False
@@ -925,6 +926,10 @@ def get_vllm_port() -> Optional[int]:
     "VLLM_USE_DEEP_GEMM":
     lambda: bool(int(os.getenv("VLLM_USE_DEEP_GEMM", "0"))),
 
+    # Whether to use E8M0 scaling when DeepGEMM is used on Blackwell GPUs.
+    # E8M0 is faster on B200 but may reduce accuracy.
+    "VLLM_USE_DEEP_GEMM_E8M0":
+    lambda: bool(int(os.getenv("VLLM_USE_DEEP_GEMM_E8M0", "1"))),
     # DeepGemm JITs the kernels on-demand. The warmup attempts to make DeepGemm
     # JIT all the required kernels before model execution so there is no
     # JIT'ing in the hot-path. However, this warmup increases the engine

vllm/model_executor/layers/fused_moe/batched_deep_gemm_moe.py

@@ -12,7 +12,7 @@
 from vllm.model_executor.layers.fused_moe.utils import _resize_cache
 from vllm.triton_utils import tl, triton
 from vllm.utils.deep_gemm import (fp8_m_grouped_gemm_nt_masked,
-                                  is_blackwell_deep_gemm_used)
+                                  is_blackwell_deep_gemm_e8m0_used)
 
 logger = init_logger(__name__)
 
@@ -176,7 +176,7 @@ def silu_mul_fp8_quant_deep_gemm(
         eps,
         fp8_min,
         fp8_max,
-        is_blackwell_deep_gemm_used(),
+        is_blackwell_deep_gemm_e8m0_used(),
         BLOCK=group_size,
         NUM_STAGES=8,
         num_warps=1,

vllm/model_executor/layers/fused_moe/fused_moe.py

@@ -40,7 +40,7 @@
 from vllm.platforms import current_platform
 from vllm.triton_utils import tl, triton
 from vllm.utils import direct_register_custom_op, is_torch_equal_or_newer
-from vllm.utils.deep_gemm import is_blackwell_deep_gemm_used
+from vllm.utils.deep_gemm import is_blackwell_deep_gemm_e8m0_used
 
 from .rocm_aiter_fused_moe import is_rocm_aiter_moe_enabled
 
@@ -1387,8 +1387,8 @@ def fused_experts(hidden_states: torch.Tensor,
     # E8M0 scale, which means we requantize the weight and input to the specific
     # scale. Fallen back to cutlass or triton for some cases would cause
     # accuracy issue.
-    should_use_deep_gemm = is_blackwell_deep_gemm_used() or _valid_deep_gemm(
-        hidden_states, w1, w2)
+    should_use_deep_gemm = is_blackwell_deep_gemm_e8m0_used(
+    ) or _valid_deep_gemm(hidden_states, w1, w2)
     if (allow_deep_gemm and use_fp8_w8a8 and should_use_deep_gemm):
         assert apply_router_weight_on_input is False
         assert is_act_and_mul, (

vllm/model_executor/layers/fused_moe/triton_deep_gemm_moe.py

@@ -10,7 +10,7 @@
     DeepGemmExperts, _valid_deep_gemm, _valid_deep_gemm_shape,
     deep_gemm_block_shape)
 from vllm.model_executor.layers.fused_moe.fused_moe import TritonExperts
-from vllm.utils.deep_gemm import is_blackwell_deep_gemm_used
+from vllm.utils.deep_gemm import is_blackwell_deep_gemm_e8m0_used
 
 
 class TritonOrDeepGemmExperts(mk.FusedMoEPermuteExpertsUnpermute):
@@ -107,7 +107,7 @@ def workspace_shapes(
         # Note: the deep gemm workspaces are strictly larger than the triton
         # workspaces so we can be pessimistic here and allocate for DeepGemm
         # even if we fall back to triton later, e.g. if expert maps are set.
-        if self.allow_deep_gemm and (is_blackwell_deep_gemm_used()
+        if self.allow_deep_gemm and (is_blackwell_deep_gemm_e8m0_used()
                                      or _valid_deep_gemm_shape(M, N, K)):
             assert self.deep_gemm_expert is not None
             return self.deep_gemm_expert.workspace_shapes(
@@ -133,7 +133,7 @@ def apply(self, output: torch.Tensor, hidden_states: torch.Tensor,
               extra_expert_args: Optional[dict[str, Any]]):
         use_deep_gemm = (self.allow_deep_gemm
                          and (_valid_deep_gemm(hidden_states, w1, w2)
-                              or is_blackwell_deep_gemm_used()))
+                              or is_blackwell_deep_gemm_e8m0_used()))
 
         experts = self.deep_gemm_expert if use_deep_gemm else self.triton_expert
         assert experts is not None

vllm/model_executor/layers/quantization/fp8.py

@@ -45,7 +45,8 @@
 from vllm.platforms import current_platform
 from vllm.scalar_type import scalar_types
 from vllm.utils import has_deep_gemm
-from vllm.utils.deep_gemm import is_blackwell_deep_gemm_used
+from vllm.utils.deep_gemm import (is_blackwell_deep_gemm_e8m0_used,
+                                  is_deep_gemm_supported)
 from vllm.utils.flashinfer import has_flashinfer_moe
 
 if TYPE_CHECKING:
@@ -415,10 +416,10 @@ def process_weights_after_loading(self, layer: Module) -> None:
             # Activations not quantized for marlin.
             del layer.input_scale
 
-        # On B200, DeepGemm only support E8M0 scale, which means we need to
+        # On B200, if E8M0 for DeepGemm is used, we need to
         # requantize the weight and input to the specific scale
         # at the same time.
-        if is_blackwell_deep_gemm_used():
+        if is_blackwell_deep_gemm_e8m0_used():
             assert layer.weight_block_size is not None
             block_sz = tuple(layer.weight_block_size)
             requant_weight_ue8m0_inplace(
@@ -505,15 +506,9 @@ def __init__(self, quant_config: Fp8Config):
             elif not self.block_quant:
                 logger.warning_once("Model is not block quantized. Not using "
                                     "DeepGemm kernels")
-            elif (current_platform.is_cuda()
-                  and current_platform.is_device_capability(90)):
+            elif (is_deep_gemm_supported()):
                 logger.info_once("Using DeepGemm kernels for Fp8MoEMethod.")
                 self.allow_deep_gemm = True
-            elif (current_platform.is_cuda()
-                  and is_blackwell_deep_gemm_used()):
-                logger.info_once("Using DeepGemm SM100 kernels for "
-                                 "Fp8MoEMethod.")
-                self.allow_deep_gemm = True
             else:
                 logger.warning_once(
                     "DeepGemm not supported on the current platform.")
@@ -725,7 +720,7 @@ def process_weights_after_loading(self, layer: Module) -> None:
 
             # DeepGemm scales need to be transposed and aligned.  We try to do
             # it ahead of time for performance reasons.
-            if self.allow_deep_gemm and not is_blackwell_deep_gemm_used():
+            if self.allow_deep_gemm and not is_blackwell_deep_gemm_e8m0_used():
                 # Lazy import to avoid CUDA initialization problems.
                 if _is_col_major(layer.w13_weight_scale_inv):
                     layer.w13_weight_scale_inv = \
@@ -851,7 +846,7 @@ def process_weights_after_loading(self, layer: Module) -> None:
             del layer.w13_input_scale
             del layer.w2_input_scale
 
-        if is_blackwell_deep_gemm_used():
+        if is_blackwell_deep_gemm_e8m0_used():
             assert layer.weight_block_size is not None
             # Re-quantise the expert weights so their scales are UE8M0.
             block_sz = tuple(layer.weight_block_size)

vllm/model_executor/layers/quantization/utils/fp8_utils.py

@@ -20,7 +20,7 @@
 from vllm.platforms import current_platform
 from vllm.triton_utils import tl, triton
 from vllm.utils import cdiv, direct_register_custom_op, has_deep_gemm
-from vllm.utils.deep_gemm import is_blackwell_deep_gemm_used
+from vllm.utils.deep_gemm import is_blackwell_deep_gemm_e8m0_used
 
 logger = init_logger(__name__)
 
@@ -394,10 +394,8 @@ def per_token_group_quant_fp8(
         tuple[torch.Tensor, torch.Tensor]: The quantized tensor and the
         scaling factor.
     """
-    # TODO(wentao): refactor this
-    # use_ue8m0 should be a global flag that could be set by user
     if use_ue8m0 is None:
-        use_ue8m0 = is_blackwell_deep_gemm_used()
+        use_ue8m0 = is_blackwell_deep_gemm_e8m0_used()
     dtype = current_platform.fp8_dtype() if dtype is None else dtype
     assert (x.shape[-1] % group_size == 0), (
         f"the last dimension of `x` {x.shape[-1]} must be divisible "

vllm/utils/deep_gemm.py

@@ -31,19 +31,37 @@ def is_deep_gemm_supported() -> bool:
 
 
 @functools.cache
-def is_blackwell_deep_gemm_used() -> bool:
-    """Return ``True`` if vLLM is configured to use DeepGEMM on a
-    Blackwell-class GPU.
+def is_blackwell_deep_gemm_e8m0_used() -> bool:
+    """Return ``True`` if vLLM is configured to use DeepGEMM "
+    "E8M0 scale on a Blackwell-class GPU.
     """
-    if not (envs.VLLM_USE_DEEP_GEMM and has_deep_gemm()):
+    if not (envs.VLLM_USE_DEEP_GEMM):
+        logger.debug_once("DeepGEMM E8M0 disabled: VLLM_USE_DEEP_GEMM=0.")
+        return False
+
+    if not has_deep_gemm():
+        logger.debug_once("DeepGEMM E8M0 disabled: DeepGEMM backend missing.")
+        return False
+
+    if not envs.VLLM_USE_DEEP_GEMM_E8M0:
+        logger.debug_once("DeepGEMM E8M0 disabled: VLLM_USE_DEEP_GEMM_E8M0=0.")
         return False
 
     _lazy_init()
+
     if _fp8_gemm_nt_impl is None:
+        logger.debug_once(
+            "DeepGEMM E8M0 disabled: _fp8_gemm_nt_impl not found")
         return False
 
-    return (current_platform.is_cuda()
-            and current_platform.is_device_capability(100))
+    enabled = (current_platform.is_cuda()
+               and current_platform.has_device_capability(100))
+    if enabled:
+        logger.debug_once("DeepGEMM E8M0 enabled on Blackwell GPU.")
+    else:
+        logger.debug_once(
+            "DeepGEMM E8M0 disabled: not running on Blackwell GPU.")
+    return enabled
 
 
 def _missing(*_: Any, **__: Any) -> NoReturn:
@@ -109,21 +127,30 @@ def fp8_gemm_nt(*args, **kwargs):
     _lazy_init()
     if _fp8_gemm_nt_impl is None:
         return _missing(*args, **kwargs)
-    return _fp8_gemm_nt_impl(*args, **kwargs)
+    return _fp8_gemm_nt_impl(
+        *args,
+        disable_ue8m0_cast=not is_blackwell_deep_gemm_e8m0_used(),
+        **kwargs)
 
 
 def m_grouped_fp8_gemm_nt_contiguous(*args, **kwargs):
     _lazy_init()
     if _grouped_impl is None:
         return _missing(*args, **kwargs)
-    return _grouped_impl(*args, **kwargs)
+    return _grouped_impl(
+        *args,
+        disable_ue8m0_cast=not is_blackwell_deep_gemm_e8m0_used(),
+        **kwargs)
 
 
 def fp8_m_grouped_gemm_nt_masked(*args, **kwargs):
     _lazy_init()
     if _grouped_masked_impl is None:
         return _missing(*args, **kwargs)
-    return _grouped_masked_impl(*args, **kwargs)
+    return _grouped_masked_impl(
+        *args,
+        disable_ue8m0_cast=not is_blackwell_deep_gemm_e8m0_used(),
+        **kwargs)
 
 
 def _ceil_to_ue8m0(x: torch.Tensor):
@@ -181,6 +208,6 @@ def calc_diff(x: torch.Tensor, y: torch.Tensor):
     "m_grouped_fp8_gemm_nt_contiguous",
     "fp8_m_grouped_gemm_nt_masked",
     "per_block_cast_to_fp8",
-    "is_blackwell_deep_gemm_used",
+    "is_blackwell_deep_gemm_e8m0_used",
     "is_deep_gemm_supported",
 ]