fix greenctx stream compability (#8090)

sgl-kernel/csrc/spatial/greenctx_stream.cu

@@ -7,52 +7,83 @@
 #include "cuda_utils.h"
 #include "greenctx_stream.h"
 
+std::vector<int64_t> create_greenctx_stream_fallback(CUgreenCtx gctx[2]) {
+  CUstream streamA, streamB;
+  CUcontext ctx;
+
+  // Stream A
+  CUDA_DRV(cuCtxFromGreenCtx(&ctx, gctx[0]));
+  CUDA_DRV(cuCtxPushCurrent(ctx));
+  CUDA_DRV(cuStreamCreate(&streamA, CU_STREAM_NON_BLOCKING));
+  CUDA_DRV(cuCtxPopCurrent(nullptr));
+
+  // Stream B
+  CUDA_DRV(cuCtxFromGreenCtx(&ctx, gctx[1]));
+  CUDA_DRV(cuCtxPushCurrent(ctx));
+  CUDA_DRV(cuStreamCreate(&streamB, CU_STREAM_NON_BLOCKING));
+  CUDA_DRV(cuCtxPopCurrent(nullptr));
+
+  return {(int64_t)streamA, (int64_t)streamB};
+}
+
+#if CUDA_VERSION >= 12050
+std::vector<int64_t> create_greenctx_stream_direct(CUgreenCtx gctx[2]) {
+  CUstream streamA;
+  CUstream streamB;
+
+  CUDA_DRV(cuGreenCtxStreamCreate(&streamA, gctx[0], CU_STREAM_NON_BLOCKING, 0));
+  CUDA_DRV(cuGreenCtxStreamCreate(&streamB, gctx[1], CU_STREAM_NON_BLOCKING, 0));
+
+  std::vector<int64_t> vec = {(int64_t)streamA, (int64_t)streamB};
+  return vec;
+}
+#endif
+
 std::vector<int64_t> create_greenctx_stream_by_value(int64_t smA, int64_t smB, int64_t device) {
+  TORCH_CHECK(CUDA_VERSION >= 12040, "Green Contexts feature requires CUDA Toolkit 12.4 or newer.");
+
   CUgreenCtx gctx[3];
   CUdevResourceDesc desc[3];
   CUdevResource input;
   CUdevResource resources[4];
-  CUstream streamA;
-  CUstream streamB;
-
   unsigned int nbGroups = 1;
 
   if (smA <= 0 || smB <= 0) {
     TORCH_CHECK(false, "SM counts must be positive");
   }
 
-  // Initialize device
-  CUDA_RT(cudaInitDevice(device, 0, 0));
-
-  // Query input SMs
   CUDA_DRV(cuDeviceGetDevResource((CUdevice)device, &input, CU_DEV_RESOURCE_TYPE_SM));
-  // We want 3/4 the device for our green context
   unsigned int minCount = (unsigned int)(smA + smB);
   unsigned int minCountA = (unsigned int)(smA);
-
   TORCH_CHECK(minCount <= input.sm.smCount, "Not enough SMs available for the requested configuration");
 
-  // Split resources
   CUDA_DRV(cuDevSmResourceSplitByCount(&resources[2], &nbGroups, &input, &resources[3], 0, minCount));
-
   CUDA_DRV(cuDevResourceGenerateDesc(&desc[2], &resources[2], 1));
   CUDA_DRV(cuGreenCtxCreate(&gctx[2], desc[2], (CUdevice)device, CU_GREEN_CTX_DEFAULT_STREAM));
   CUDA_DRV(cuGreenCtxGetDevResource(gctx[2], &input, CU_DEV_RESOURCE_TYPE_SM));
   CUDA_DRV(cuDevSmResourceSplitByCount(&resources[0], &nbGroups, &input, &resources[1], 0, minCountA));
-
   CUDA_DRV(cuDevResourceGenerateDesc(&desc[0], &resources[0], 1));
   CUDA_DRV(cuGreenCtxCreate(&gctx[0], desc[0], (CUdevice)device, CU_GREEN_CTX_DEFAULT_STREAM));
   CUDA_DRV(cuDevResourceGenerateDesc(&desc[1], &resources[1], 1));
   CUDA_DRV(cuGreenCtxCreate(&gctx[1], desc[1], (CUdevice)device, CU_GREEN_CTX_DEFAULT_STREAM));
-
-  CUDA_DRV(cuGreenCtxStreamCreate(&streamA, gctx[0], CU_STREAM_NON_BLOCKING, 0));
-  CUDA_DRV(cuGreenCtxStreamCreate(&streamB, gctx[1], CU_STREAM_NON_BLOCKING, 0));
-
   int smCountA = resources[0].sm.smCount;
   int smCountB = resources[1].sm.smCount;
 
+  std::vector<int64_t> stream_handles;
+
+#if CUDA_VERSION >= 12050
+  stream_handles = create_greenctx_stream_direct(gctx);
+#else
+  stream_handles = create_greenctx_stream_fallback(gctx);
+#endif
+
   CUDA_DRV(cuGreenCtxDestroy(gctx[2]));
 
-  std::vector<int64_t> vec = {(int64_t)streamA, (int64_t)streamB, smCountA, smCountB};
+  std::vector<int64_t> vec = {
+      stream_handles[0],  // streamA
+      stream_handles[1],  // streamB
+      (int64_t)smCountA,
+      (int64_t)smCountB};
+
   return vec;
 }