TheRock/rocm-systems/projects/rocprofiler-compute/sample/vsequential_access.cpp

// Copyright (c) Advanced Micro Devices, Inc.
// SPDX-License-Identifier:  MIT

/*
An example code to execute sequential access to explore cache hits/misses in L2 Cache.
*/

#include <hip/hip_runtime.h>
#include <iostream>
#include <assert.h>

#define HIP_ASSERT(x) (assert((x)==hipSuccess))

// Kernel: sequential access, each thread reads/writes an element in order
__global__ void sequentialAccessKernel(int *d_data, int N)
{
    int tid = blockIdx.x * blockDim.x + threadIdx.x;
    if (tid < N)
    {
        d_data[tid] += 1;
    }
}

int main()
{
    const int N = 1 << 20; // 1M elements
    size_t size = N * sizeof(int);
    // Allocate host memory
    int *h_data = (int *)malloc(size);
    std::fill_n(h_data, N, 0);

    // Allocate device memory
    int *d_data;
    HIP_ASSERT(hipMalloc(&d_data, size));

    // Copy h_data to device
    HIP_ASSERT(hipMemcpy(d_data, h_data, size, hipMemcpyHostToDevice));

    // Configure kernel
    dim3 blockSize(64);
    dim3 gridSize((N + blockSize.x - 1) / blockSize.x);

    // Repeat the launch so the profile is robust.
    const int kIters = 30;
    for (int i = 0; i < kIters; ++i)
    {
        hipLaunchKernelGGL(sequentialAccessKernel, gridSize, blockSize, 0, 0, d_data, N);
    }
    HIP_ASSERT(hipDeviceSynchronize());

    // Copy back to host
    HIP_ASSERT(hipMemcpy(h_data, d_data, size, hipMemcpyDeviceToHost));

    // Cleanup
    HIP_ASSERT(hipFree(d_data));
    free(h_data);

    std::cout << "SequentialAccess HIP test completed.\n";
    return 0;
}