Automated PR - 2026-07-07

packages/ltx-kernels/csrc/include/cuda/configs.cuh

@@ -0,0 +1,88 @@
+/**
+ * @file configs.cuh
+ * @brief Configuration constants and compile-time settings for ltx-kernels.
+ *
+ * This header defines the tunable parameters and constants used throughout
+ * the ltx-kernels communication library. These values are chosen to balance
+ * performance across different GPU architectures.
+ */
+
+#pragma once
+
+#include <cstdint>
+#include <cuda_bf16.h>
+#include <cuda_runtime.h>
+
+namespace ltx_kernels {
+// =============================================================================
+// Synchronization Configuration
+// =============================================================================
+
+/**
+ * @brief Default barrier timeout in seconds.
+ *
+ * If a barrier wait exceeds this timeout, the kernel traps to indicate a deadlock or
+ * communication failure. All2All converts it to clock cycles using the device's peak SM clock
+ * (cudaDeviceGetAttribute(cudaDevAttrClockRate)), so the wall-clock guard holds regardless of GPU.
+ */
+constexpr double DEFAULT_BARRIER_TIMEOUT_SECONDS = 10.0;
+
+// =============================================================================
+// Hardware Limits
+// =============================================================================
+
+/**
+ * @brief Maximum number of peer GPUs supported for IPC communication.
+ *
+ * This limits the size of static arrays for buffer pointers and barrier signals.
+ * Set to 8 to support up to 8-way tensor parallelism (common for DGX systems).
+ */
+constexpr int MAX_NUM_PEERS = 8;
+
+// =============================================================================
+// Kernel Configuration
+// =============================================================================
+
+/**
+ * @brief Default number of threads per block for All2All kernels.
+ *
+ * Used by send_recv_all2all and gather_heads kernels. The value 512 provides
+ * good occupancy while leaving registers for complex pointer arithmetic.
+ */
+constexpr int DEFAULT_KERNEL_THREADS = 512;
+
+/**
+ * @brief Number of threads per block for the AllGather kernel.
+ *
+ * AllGather uses more threads (1024) because its memory access pattern
+ * is simpler (no head selection), allowing higher thread-level parallelism.
+ */
+constexpr int ALLGATHER_KERNEL_THREADS = 1024;
+
+} // namespace ltx_kernels
+
+// =============================================================================
+// Torch/CUDA Compatibility Fixes
+// =============================================================================
+
+/*
+ * PyTorch sometimes disables CUDA half/bfloat16 operators and conversions
+ * to avoid ambiguity in template resolution. We re-enable them here since
+ * our kernels explicitly handle these types.
+ */
+
+#ifdef __CUDA_NO_HALF_CONVERSIONS__
+#undef __CUDA_NO_HALF_CONVERSIONS__
+#endif
+#ifdef __CUDA_NO_HALF_OPERATORS__
+#undef __CUDA_NO_HALF_OPERATORS__
+#endif
+#ifdef __CUDA_NO_HALF2_OPERATORS__
+#undef __CUDA_NO_HALF2_OPERATORS__
+#endif
+#ifdef __CUDA_NO_BFLOAT16_CONVERSIONS__
+#undef __CUDA_NO_BFLOAT16_CONVERSIONS__
+#endif
+#ifdef __CUDA_NO_BFLOAT162_OPERATORS__
+#undef __CUDA_NO_BFLOAT162_OPERATORS__
+#endif