Add some compile-time CL utilities

2025-10-25 03:39:42 -04:00
parent 266cabcddb
commit 0e872042ee
5 changed files with 406 additions and 0 deletions
@@ -0,0 +1,90 @@
+#include <CL/cl.h>
+#include <iostream>
+#include <vector>
+#include <chrono>
+#include <cstring>
+
+void checkCLError(cl_int err, const char* msg) {
+    if (err != CL_SUCCESS) {
+        std::cerr << "OpenCL Error " << err << " at: " << msg << std::endl;
+        exit(1);
+    }
+}
+
+int main() {
+    cl_uint numPlatforms = 0;
+    checkCLError(clGetPlatformIDs(0, nullptr, &numPlatforms), "get num platforms");
+    std::vector<cl_platform_id> platforms(numPlatforms);
+    checkCLError(clGetPlatformIDs(numPlatforms, platforms.data(), nullptr), "get platforms");
+
+    std::cout << "Found " << numPlatforms << " OpenCL platforms\n\n";
+
+    for (cl_uint p = 0; p < numPlatforms; ++p) {
+        char platformName[256];
+        clGetPlatformInfo(platforms[p], CL_PLATFORM_NAME, sizeof(platformName), platformName, nullptr);
+        std::cout << "Platform " << p << ": " << platformName << "\n";
+
+        cl_uint numDevices = 0;
+        clGetDeviceIDs(platforms[p], CL_DEVICE_TYPE_ALL, 0, nullptr, &numDevices);
+        std::vector<cl_device_id> devices(numDevices);
+        clGetDeviceIDs(platforms[p], CL_DEVICE_TYPE_ALL, numDevices, devices.data(), nullptr);
+
+        for (cl_uint d = 0; d < numDevices; ++d) {
+            char deviceName[256];
+            clGetDeviceInfo(devices[d], CL_DEVICE_NAME, sizeof(deviceName), deviceName, nullptr);
+            std::cout << "  Device " << d << ": " << deviceName << "\n";
+
+            cl_bool unifiedMem = CL_FALSE;
+            clGetDeviceInfo(devices[d], CL_DEVICE_HOST_UNIFIED_MEMORY, sizeof(unifiedMem), &unifiedMem, nullptr);
+            std::cout << "    Host-Device unified memory: " << (unifiedMem ? "Yes" : "No") << "\n";
+
+#ifdef CL_DEVICE_SVM_CAPABILITIES
+            cl_device_svm_capabilities svmCaps = 0;
+            clGetDeviceInfo(devices[d], CL_DEVICE_SVM_CAPABILITIES, sizeof(svmCaps), &svmCaps, nullptr);
+            std::cout << "    SVM capabilities:\n";
+            if (!svmCaps) std::cout << "      None\n";
+            if (svmCaps & CL_DEVICE_SVM_COARSE_GRAIN_BUFFER)
+                std::cout << "      - Coarse-grain buffer sharing\n";
+            if (svmCaps & CL_DEVICE_SVM_FINE_GRAIN_BUFFER)
+                std::cout << "      - Fine-grain buffer sharing\n";
+            if (svmCaps & CL_DEVICE_SVM_FINE_GRAIN_SYSTEM)
+                std::cout << "      - Fine-grain system sharing\n";
+            if (svmCaps & CL_DEVICE_SVM_ATOMICS)
+                std::cout << "      - Atomics supported\n";
+#endif
+
+            // Optional runtime test: check if CL_MEM_USE_HOST_PTR buffer reuses pointer
+            const size_t bufSize = 1024 * 1024;
+            std::vector<char> hostBuffer(bufSize, 42);
+
+            cl_int err;
+            cl_context ctx = clCreateContext(nullptr, 1, &devices[d], nullptr, nullptr, &err);
+            checkCLError(err, "create context");
+
+            cl_mem buf = clCreateBuffer(ctx, CL_MEM_USE_HOST_PTR, bufSize, hostBuffer.data(), &err);
+            checkCLError(err, "create buffer");
+
+            cl_command_queue q = clCreateCommandQueue(ctx, devices[d], 0, &err);
+            checkCLError(err, "create queue");
+
+            // Simple host → device → host round-trip test
+            cl_event evt;
+
+            auto start = std::chrono::high_resolution_clock::now();
+
+	void* mapped = clEnqueueMapBuffer(q, buf, CL_TRUE, CL_MAP_READ, 0, bufSize, 0, nullptr, &evt, &err);
+	checkCLError(err, "map buffer");
+	clWaitForEvents(1, &evt);
+
+            clReleaseMemObject(buf);
+            auto end = std::chrono::high_resolution_clock::now();
+            std::chrono::duration<double, std::milli> elapsed = end - start;
+            std::cout << "    Map latency: " << elapsed.count() << " ms (lower → likely zero-copy)\n";
+
+            clReleaseCommandQueue(q);
+            clReleaseContext(ctx);
+        }
+        std::cout << std::endl;
+    }
+    return 0;
+}