[Kernel] Change interface to Mamba causal_conv1d_update for continuou…

…s batching (vllm-project#8012)

csrc/mamba/causal_conv1d/causal_conv1d.cu

@@ -198,7 +198,8 @@ causal_conv1d_update(const at::Tensor &x,
                      const at::Tensor &conv_state,
                      const at::Tensor &weight,
                      const c10::optional<at::Tensor> &bias_,
-                     bool silu_activation) {
+                     bool silu_activation,
+                     const c10::optional<at::Tensor> &conv_state_indices_) {
     auto input_type = x.scalar_type();
     auto weight_type = weight.scalar_type();
     TORCH_CHECK(input_type == at::ScalarType::Float || input_type == at::ScalarType::Half || input_type == at::ScalarType::BFloat16);
@@ -216,7 +217,6 @@ causal_conv1d_update(const at::Tensor &x,
     const int width = weight.size(-1);
 
     CHECK_SHAPE(x, batch_size, dim);
-    CHECK_SHAPE(conv_state, batch_size, dim, width);
     CHECK_SHAPE(weight, dim, width);
 
     TORCH_CHECK(width >= 2 && width <= 4, "causal_conv1d only supports width between 2 and 4");
@@ -241,6 +241,22 @@ causal_conv1d_update(const at::Tensor &x,
     params.conv_state_c_stride = conv_state.stride(1);
     params.conv_state_l_stride = conv_state.stride(2);
 
+    if (conv_state_indices_.has_value()) {
+        auto conv_state_indices = conv_state_indices_.value();
+        TORCH_CHECK(conv_state_indices.scalar_type() == torch::kInt32)
+        TORCH_CHECK(conv_state_indices.is_cuda());
+        TORCH_CHECK(conv_state_indices.stride(0) == 1)
+        CHECK_SHAPE(conv_state_indices, batch_size);
+
+        int conv_state_entries = conv_state.size(0);
+        CHECK_SHAPE(conv_state, conv_state_entries, dim, width);
+
+        params.conv_state_indices_ptr = conv_state_indices.data_ptr<int32_t>();
+    } else {
+        CHECK_SHAPE(conv_state, batch_size, dim, width);
+        params.conv_state_indices_ptr = nullptr;
+    }
+
     // Otherwise the kernel will be launched from cuda:0 device
     // Cast to char to avoid compiler warning about narrowing
     at::cuda::CUDAGuard device_guard{(char)x.get_device()};
@@ -646,8 +662,16 @@ void causal_conv1d_update_kernel(ConvParamsBase params) {
     const int channel_id = blockIdx.y * kNThreads + tidx;
     input_t *x = reinterpret_cast<input_t *>(params.x_ptr) + batch_id * params.x_batch_stride
         + channel_id * params.x_c_stride;
-    input_t *conv_state = reinterpret_cast<input_t *>(params.conv_state_ptr) + batch_id * params.conv_state_batch_stride
+
+    // If params.conv_state_batch_indices is set, then the conv state is gathered from the conv state tensor
+    // along the batch axis. Otherwise, the conv state coordinate is the same as the batch id.
+    const int conv_state_batch_coord = params.conv_state_indices_ptr == nullptr
+        ? batch_id
+        : params.conv_state_indices_ptr[batch_id];
+    input_t *conv_state = reinterpret_cast<input_t *>(params.conv_state_ptr) 
+        + conv_state_batch_coord * params.conv_state_batch_stride
         + channel_id * params.conv_state_c_stride;
+
     weight_t *weight = reinterpret_cast<weight_t *>(params.weight_ptr) + channel_id * params.weight_c_stride;
     input_t *out = reinterpret_cast<input_t *>(params.out_ptr) + batch_id * params.out_batch_stride
         + channel_id * params.out_c_stride;

csrc/mamba/causal_conv1d/causal_conv1d.h

@@ -36,6 +36,10 @@ struct ConvParamsBase {
 
     void *__restrict__ conv_state_ptr;
 
+    // For the continuous batching case. Makes it so that the mamba state for 
+    // the current batch doesn't need to be a contiguous tensor.
+    int32_t *__restrict__ conv_state_indices_ptr;
+
     void *__restrict__ seq_idx_ptr;
 
     // No __restrict__ since initial_states could be the same as final_states.

csrc/ops.h

@@ -222,11 +222,10 @@ std::vector<torch::Tensor> selective_scan_fwd(
     const c10::optional<torch::Tensor>& index_,
     const c10::optional<torch::Tensor>& x);
 
-at::Tensor causal_conv1d_update(const at::Tensor& x,
-                                const at::Tensor& conv_state,
-                                const at::Tensor& weight,
-                                const c10::optional<at::Tensor>& bias_,
-                                bool silu_activation);
+at::Tensor causal_conv1d_update(
+    const at::Tensor& x, const at::Tensor& conv_state, const at::Tensor& weight,
+    const c10::optional<at::Tensor>& bias, bool silu_activation,
+    const c10::optional<at::Tensor>& conv_state_indices);
 
 at::Tensor causal_conv1d_fwd(const at::Tensor& x, const at::Tensor& weight,
                              const c10::optional<at::Tensor>& bias_,

csrc/torch_bindings.cpp

@@ -279,8 +279,9 @@ TORCH_LIBRARY_EXPAND(TORCH_EXTENSION_NAME, ops) {
       "causal_conv1d_update(Tensor! x,"
       "Tensor! conv_state,"
       "Tensor! weight,"
-      "Tensor? bias_,"
-      "bool silu_activation) -> Tensor");
+      "Tensor? bias,"
+      "bool silu_activation,"
+      "Tensor? conv_state_indices) -> Tensor");
   ops.impl("causal_conv1d_update", torch::kCUDA, &causal_conv1d_update);
 
   ops.def(

tests/kernels/test_causal_conv1d.py

@@ -203,3 +203,61 @@ def test_causal_conv1d_update(batch, dim, width, has_bias, silu_activation,
 
     assert torch.equal(conv_state, conv_state_ref)
     assert torch.allclose(out, out_ref, rtol=rtol, atol=atol)
+
+
+@pytest.mark.parametrize("itype",
+                         [torch.float32, torch.float16, torch.bfloat16])
+@pytest.mark.parametrize("silu_activation", [False, True])
+@pytest.mark.parametrize("has_bias", [False, True])
+@pytest.mark.parametrize("seqlen", [1, 4, 5])
+@pytest.mark.parametrize("width", [2, 3, 4])
+@pytest.mark.parametrize("dim", [2048, 2048 + 16, 4096])
+def test_causal_conv1d_update_with_batch_gather(dim, width, seqlen, has_bias,
+                                                silu_activation, itype):
+    device = "cuda"
+    rtol, atol = (3e-4, 1e-3) if itype == torch.float32 else (3e-3, 5e-3)
+    if itype == torch.bfloat16:
+        rtol, atol = 1e-2, 5e-2
+
+    # set seed
+    torch.random.manual_seed(0)
+    batch = 64
+
+    x = torch.randn(batch, dim, device=device, dtype=itype)
+
+    total_entries = 10 * batch
+    conv_state = torch.randn(total_entries,
+                             dim,
+                             width,
+                             device=device,
+                             dtype=itype)
+    conv_state_indices = torch.randperm(total_entries)[:batch].to(
+        dtype=torch.int32, device=device)
+
+    weight = torch.randn(dim,
+                         width,
+                         device=device,
+                         dtype=itype,
+                         requires_grad=True)
+    if has_bias:
+        bias = torch.randn(dim, device=device, dtype=itype, requires_grad=True)
+    else:
+        bias = None
+    conv_state_ref = conv_state[conv_state_indices, :].detach().clone()
+    activation = None if not silu_activation else "silu"
+    out = causal_conv1d_update(x,
+                               conv_state,
+                               weight,
+                               bias,
+                               activation=activation,
+                               conv_state_indices=conv_state_indices)
+    out_ref = causal_conv1d_update_ref(x,
+                                       conv_state_ref,
+                                       weight,
+                                       bias,
+                                       activation=activation)
+
+    print(f"Output max diff: {(out - out_ref).abs().max().item()}")
+    print(f"Output mean diff: {(out - out_ref).abs().mean().item()}")
+    assert torch.equal(conv_state[conv_state_indices, :], conv_state_ref)
+    assert torch.allclose(out, out_ref, rtol=rtol, atol=atol)

vllm/_custom_ops.py

@@ -768,11 +768,17 @@ def causal_conv1d_fwd(x: torch.Tensor, weight: torch.Tensor,
                                           silu_activation)
 
 
-def causal_conv1d_update(x: torch.Tensor, conv_state: torch.Tensor,
-                         weight: torch.Tensor, bias_: Optional[torch.Tensor],
-                         silu_activation: bool) -> torch.Tensor:
+def causal_conv1d_update(
+    x: torch.Tensor,
+    conv_state: torch.Tensor,
+    weight: torch.Tensor,
+    bias_: Optional[torch.Tensor],
+    silu_activation: bool,
+    conv_state_indices: Optional[torch.Tensor],
+) -> torch.Tensor:
     return torch.ops._C.causal_conv1d_update(x, conv_state, weight, bias_,
-                                             silu_activation)
+                                             silu_activation,
+                                             conv_state_indices)
 
 
 def selective_scan_fwd(u: torch.Tensor, delta: torch.Tensor, A: torch.Tensor,

vllm/model_executor/layers/mamba/ops/causal_conv1d.py

@@ -1,4 +1,5 @@
 # Copyright (c) 2024, Tri Dao.
+# Adapted from https://github.com/Dao-AILab/causal-conv1d/blob/main/causal_conv1d/causal_conv1d_interface.py
 
 from typing import Optional
 
@@ -70,17 +71,22 @@ def causal_conv1d_update(x: torch.Tensor,
                          conv_state: torch.Tensor,
                          weight: torch.Tensor,
                          bias: Optional[torch.Tensor] = None,
-                         activation: Optional[str] = None):
+                         activation: Optional[str] = None,
+                         conv_state_indices: Optional[torch.Tensor] = None):
     """
     x: (batch, dim)
     conv_state: (batch, dim, width)
     weight: (dim, width)
     bias: (dim,)
+    conv_state_indices: (batch,), dtype int32
+        If not None, the conv_state is a larger tensor along the batch dim, 
+        and we are selecting the batch coords specified by conv_state_indices.
+        Useful for a continuous batching scenario.
 
     out: (batch, dim)
     """
     if activation not in [None, "silu", "swish"]:
         raise NotImplementedError("activation must be None, silu, or swish")
     activation_bool = activation in ["silu", "swish"]
     return ops.causal_conv1d_update(x, conv_state, weight, bias,
-                                    activation_bool)
+                                    activation_bool, conv_state_indices)