Sync HIP documentation 2025-10-20 (#1258)
* Add examples to tools folder * Correct P2P memory access section * Sync poriting guide * Add HIP Graph tutorial * Add hint about using amdgpu-dkms for IPC API * Add a few more env variables
This commit is contained in:
@@ -11,92 +11,10 @@ example and comparison table. For a complete list of mappings, visit :ref:`HIPIF
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The following CUDA code example illustrates several CUDA API syntaxes.
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.. code-block:: cpp
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#include <iostream>
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#include <vector>
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#include <cuda_runtime.h>
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__global__ void block_reduction(const float* input, float* output, int num_elements)
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{
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extern __shared__ float s_data[];
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int tid = threadIdx.x;
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int global_id = blockDim.x * blockIdx.x + tid;
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if (global_id < num_elements)
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{
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s_data[tid] = input[global_id];
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}
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else
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{
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s_data[tid] = 0.0f;
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}
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__syncthreads();
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for (int stride = blockDim.x / 2; stride > 0; stride >>= 1)
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{
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if (tid < stride)
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{
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s_data[tid] += s_data[tid + stride];
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}
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__syncthreads();
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}
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if (tid == 0)
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{
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output[blockIdx.x] = s_data[0];
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}
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}
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int main()
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{
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int threads = 256;
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const int num_elements = 50000;
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std::vector<float> h_a(num_elements);
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std::vector<float> h_b((num_elements + threads - 1) / threads);
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for (int i = 0; i < num_elements; ++i)
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{
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h_a[i] = rand() / static_cast<float>(RAND_MAX);
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}
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float *d_a, *d_b;
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cudaMalloc(&d_a, h_a.size() * sizeof(float));
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cudaMalloc(&d_b, h_b.size() * sizeof(float));
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cudaStream_t stream;
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cudaStreamCreateWithFlags(&stream, cudaStreamNonBlocking);
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cudaEvent_t start_event, stop_event;
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cudaEventCreate(&start_event);
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cudaEventCreate(&stop_event);
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cudaMemcpyAsync(d_a, h_a.data(), h_a.size() * sizeof(float), cudaMemcpyHostToDevice, stream);
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cudaEventRecord(start_event, stream);
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int blocks = (num_elements + threads - 1) / threads;
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block_reduction<<<blocks, threads, threads * sizeof(float), stream>>>(d_a, d_b, num_elements);
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cudaMemcpyAsync(h_b.data(), d_b, h_b.size() * sizeof(float), cudaMemcpyDeviceToHost, stream);
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cudaEventRecord(stop_event, stream);
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cudaEventSynchronize(stop_event);
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cudaEventElapsedTime(&milliseconds, start_event, stop_event);
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std::cout << "Kernel execution time: " << milliseconds << " ms\n";
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cudaFree(d_a);
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cudaFree(d_b);
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cudaEventDestroy(start_event);
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cudaEventDestroy(stop_event);
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cudaStreamDestroy(stream);
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return 0;
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}
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.. literalinclude:: ../tools/example_codes/block_reduction.cu
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:start-after: // [sphinx-start]
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:end-before: // [sphinx-end]
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:language: cpp
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The following table maps CUDA API functions to corresponding HIP API functions, as demonstrated in the
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preceding code examples.
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@@ -337,117 +337,7 @@ The kernel function ``computeDFT`` shows various HIP complex math operations in
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The example also demonstrates proper use of complex number handling on both host and device, including
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memory allocation, transfer, and validation of results between CPU and GPU implementations.
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.. code-block:: cpp
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#include <hip/hip_runtime.h>
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#include <hip/hip_complex.h>
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#include <iostream>
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#include <vector>
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#include <cmath>
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#define HIP_CHECK(expression) \
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{ \
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const hipError_t err = expression; \
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if (err != hipSuccess) { \
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std::cerr << "HIP error: " \
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<< hipGetErrorString(err) \
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<< " at " << __LINE__ << "\n"; \
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exit(EXIT_FAILURE); \
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} \
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}
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// Kernel to compute DFT
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__global__ void computeDFT(const float* input,
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hipFloatComplex* output,
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const int N)
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{
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int k = blockIdx.x * blockDim.x + threadIdx.x;
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if (k >= N) return;
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hipFloatComplex sum = make_hipFloatComplex(0.0f, 0.0f);
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for (int n = 0; n < N; n++) {
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float angle = -2.0f * M_PI * k * n / N;
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hipFloatComplex w = make_hipFloatComplex(cosf(angle), sinf(angle));
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hipFloatComplex x = make_hipFloatComplex(input[n], 0.0f);
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sum = hipCaddf(sum, hipCmulf(x, w));
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}
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output[k] = sum;
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}
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// CPU implementation of DFT for verification
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std::vector<hipFloatComplex> cpuDFT(const std::vector<float>& input) {
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const int N = input.size();
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std::vector<hipFloatComplex> result(N);
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for (int k = 0; k < N; k++) {
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hipFloatComplex sum = make_hipFloatComplex(0.0f, 0.0f);
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for (int n = 0; n < N; n++) {
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float angle = -2.0f * M_PI * k * n / N;
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hipFloatComplex w = make_hipFloatComplex(cosf(angle), sinf(angle));
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hipFloatComplex x = make_hipFloatComplex(input[n], 0.0f);
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sum = hipCaddf(sum, hipCmulf(x, w));
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}
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result[k] = sum;
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}
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return result;
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}
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int main() {
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const int N = 256; // Signal length
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const int blockSize = 256;
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// Generate input signal: sum of two sine waves
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std::vector<float> signal(N);
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for (int i = 0; i < N; i++) {
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float t = static_cast<float>(i) / N;
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signal[i] = sinf(2.0f * M_PI * 10.0f * t) + // 10 Hz component
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0.5f * sinf(2.0f * M_PI * 20.0f * t); // 20 Hz component
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}
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// Compute reference solution on CPU
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std::vector<hipFloatComplex> cpu_output = cpuDFT(signal);
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// Allocate device memory
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float* d_signal;
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hipFloatComplex* d_output;
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HIP_CHECK(hipMalloc(&d_signal, N * sizeof(float)));
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HIP_CHECK(hipMalloc(&d_output, N * sizeof(hipFloatComplex)));
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// Copy input to device
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HIP_CHECK(hipMemcpy(d_signal, signal.data(), N * sizeof(float),
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hipMemcpyHostToDevice));
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// Launch kernel
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dim3 grid((N + blockSize - 1) / blockSize);
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dim3 block(blockSize);
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computeDFT<<<grid, block>>>(d_signal, d_output, N);
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HIP_CHECK(hipGetLastError());
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// Get GPU results
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std::vector<hipFloatComplex> gpu_output(N);
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HIP_CHECK(hipMemcpy(gpu_output.data(), d_output, N * sizeof(hipFloatComplex),
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hipMemcpyDeviceToHost));
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// Verify results
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bool passed = true;
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const float tolerance = 1e-5f; // Adjust based on precision requirements
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for (int i = 0; i < N; i++) {
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float diff_real = std::abs(hipCrealf(gpu_output[i]) - hipCrealf(cpu_output[i]));
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float diff_imag = std::abs(hipCimagf(gpu_output[i]) - hipCimagf(cpu_output[i]));
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if (diff_real > tolerance || diff_imag > tolerance) {
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passed = false;
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break;
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}
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}
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std::cout << "DFT Verification: " << (passed ? "PASSED" : "FAILED") << "\n";
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// Cleanup
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HIP_CHECK(hipFree(d_signal));
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HIP_CHECK(hipFree(d_output));
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return passed ? 0 : 1;
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}
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.. literalinclude:: ../tools/example_codes/complex_math.hip
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:start-after: // [sphinx-start]
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:end-before: // [sphinx-end]
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:language: cpp
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@@ -27,7 +27,7 @@ and :doc:`GPU isolation <rocm:conceptual/gpu-isolation>`.
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-
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* - | ``AMD_LOG_MASK``
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| Specifies HIP log filters. Here is the ` complete list of log masks <https://github.com/ROCm/clr/blob/develop/rocclr/utils/debug.hpp#L40>`_.
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| Specifies HIP log filters. Here is the `complete list of log masks <https://github.com/ROCm/rocm-systems/blob/develop/projects/clr/rocclr/utils/debug.hpp#L48>`_.
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- ``0x7FFFFFFF``
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- | 0x1: Log API calls.
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| 0x2: Kernel and copy commands and barriers.
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@@ -49,8 +49,16 @@ and :doc:`GPU isolation <rocm:conceptual/gpu-isolation>`.
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| 0x20000: Memory allocation.
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| 0x40000: Memory pool allocation, including memory in graphs.
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| 0x80000: Timestamp details.
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| 0x100000: Comgr path information print.
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| 0xFFFFFFFF: Log always even mask flag is zero.
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* - | ``HIP_FORCE_DEV_KERNARG``
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| Forces kernel arguments to be stored in device memory to reduce latency.
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| Can improve performance by 2-3 µs for some kernels.
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- ``1``
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- | 0: Disable
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| 1: Enable
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* - | ``HIP_LAUNCH_BLOCKING``
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| Used for serialization on kernel execution.
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- ``0``
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@@ -14,7 +14,7 @@ environment variables in HIP are collected in the following table.
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* - | ``ROCR_VISIBLE_DEVICES``
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| A list of device indices or UUIDs that will be exposed to applications.
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- :doc:`GPU isolation <rocm:conceptual/gpu-isolation>`, :doc:`Setting the number of compute units <rocm:how-to/setting-cus>`
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- Example: ``0,GPU-DEADBEEFDEADBEEF``
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- Example: ``0,GPU-4b2c1a9f-8d3e-6f7a-b5c9-2e4d8a1f6c3b``
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* - | ``GPU_DEVICE_ORDINAL``
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| Devices indices exposed to OpenCL and HIP applications.
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@@ -25,3 +25,11 @@ environment variables in HIP are collected in the following table.
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| Device indices exposed to HIP applications.
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- :doc:`GPU isolation <rocm:conceptual/gpu-isolation>`, :doc:`HIP debugging <hip:how-to/debugging>`
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- Example: ``0,2``
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.. admonition:: Recommendation
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* On Linux, use ``ROCR_VISIBLE_DEVICES``.
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* On Windows, use ``HIP_VISIBLE_DEVICES``.
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* For portability across different vendors, use ``CUDA_VISIBLE_DEVICES``.
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@@ -55,6 +55,12 @@ pages:
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- | 0: Disable
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| 1: Enable
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* - | ``GPU_SINGLE_ALLOC_PERCENT``
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| Limits the maximum size of a single memory allocation as a percentage of GPU memory.
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- ``100``
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- | Unit: Percentage
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| Prevents single allocations from consuming all available GPU memory.
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* - | ``GPU_MAX_HEAP_SIZE``
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| Set maximum size of the GPU heap to % of board memory.
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- ``100``
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@@ -16,19 +16,19 @@ different features in HIP.
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- ``--gpu-architecture=gfx906:sramecc+:xnack``, ``-fgpu-rdc``
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* - | ``AMD_COMGR_SAVE_TEMPS``
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| Controls the deletion of temporary files generated during the compilation of COMGR. These files do not appear in the current working directory, but are instead left in a platform-specific temporary directory.
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| Controls the deletion of temporary files generated during the compilation of Comgr. These files do not appear in the current working directory, but are instead left in a platform-specific temporary directory.
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- Unset by default.
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- | 0: Temporary files are deleted automatically.
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| Non zero integer: Turn off the temporary files deletion.
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* - | ``AMD_COMGR_EMIT_VERBOSE_LOGS``
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| Sets logging of COMGR to include additional Comgr-specific informational messages.
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| Sets logging of Comgr to include additional Comgr-specific informational messages.
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- Unset by default.
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- | 0: Verbose log disabled.
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| Non zero integer: Verbose log enabled.
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* - | ``AMD_COMGR_REDIRECT_LOGS``
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| Controls redirect logs of COMGR.
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| Controls redirect logs of Comgr.
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- Unset by default.
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- | `stdout` / `-`: Redirected to the standard output.
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| `stderr`: Redirected to the error stream.
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@@ -24,88 +24,10 @@ The following C++ example shows a simplified method for computing ULP difference
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HIP and standard C++ math functions by first finding where the maximum absolute error
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occurs.
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.. code-block:: cpp
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#include <hip/hip_runtime.h>
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#include <iostream>
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#include <vector>
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#include <cmath>
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#include <limits>
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#define HIP_CHECK(expression) \
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{ \
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const hipError_t err = expression; \
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if (err != hipSuccess) { \
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std::cerr << "HIP error: " \
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<< hipGetErrorString(err) \
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<< " at " << __LINE__ << "\n"; \
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exit(EXIT_FAILURE); \
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} \
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}
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// Simple ULP difference calculator
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int64_t ulp_diff(float a, float b) {
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if (a == b) return 0;
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union { float f; int32_t i; } ua{a}, ub{b};
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// For negative values, convert to a positive-based representation
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if (ua.i < 0) ua.i = std::numeric_limits<int32_t>::max() - ua.i;
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if (ub.i < 0) ub.i = std::numeric_limits<int32_t>::max() - ub.i;
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return std::abs((int64_t)ua.i - (int64_t)ub.i);
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}
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// Test kernel
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__global__ void test_sin(float* out, int n) {
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int i = blockIdx.x * blockDim.x + threadIdx.x;
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if (i < n) {
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float x = -M_PI + (2.0f * M_PI * i) / (n - 1);
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out[i] = sin(x);
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}
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}
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int main() {
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const int n = 1000000;
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const int blocksize = 256;
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std::vector<float> outputs(n);
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float* d_out;
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HIP_CHECK(hipMalloc(&d_out, n * sizeof(float)));
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dim3 threads(blocksize);
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dim3 blocks((n + blocksize - 1) / blocksize); // Fixed grid calculation
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test_sin<<<blocks, threads>>>(d_out, n);
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HIP_CHECK(hipPeekAtLastError());
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HIP_CHECK(hipMemcpy(outputs.data(), d_out, n * sizeof(float), hipMemcpyDeviceToHost));
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// Step 1: Find the maximum absolute error
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double max_abs_error = 0.0;
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float max_error_output = 0.0;
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float max_error_expected = 0.0;
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for (int i = 0; i < n; i++) {
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float x = -M_PI + (2.0f * M_PI * i) / (n - 1);
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float expected = std::sin(x);
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double abs_error = std::abs(outputs[i] - expected);
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if (abs_error > max_abs_error) {
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max_abs_error = abs_error;
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max_error_output = outputs[i];
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max_error_expected = expected;
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}
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}
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// Step 2: Compute ULP difference based on the max absolute error pair
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int64_t max_ulp = ulp_diff(max_error_output, max_error_expected);
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// Output results
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std::cout << "Max Absolute Error: " << max_abs_error << std::endl;
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std::cout << "Max ULP Difference: " << max_ulp << std::endl;
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std::cout << "Max Error Values -> Got: " << max_error_output
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<< ", Expected: " << max_error_expected << std::endl;
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HIP_CHECK(hipFree(d_out));
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return 0;
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}
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.. literalinclude:: ../tools/example_codes/math.hip
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:start-after: // [sphinx-start]
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:end-before: // [sphinx-end]
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:language: cpp
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Standard mathematical functions
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===============================
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Reference in New Issue
Block a user