如何设置原子操作中的CUDA浮点舍入模式？

可以使用CUDA提供的cudaDeviceSetLimit函数来设置原子操作中的浮点舍入模式。具体步骤如下：

1. 首先，需要在CUDA头文件中包含cuda_fp16.h，以便使用半精度浮点类型。

#include <cuda_fp16.h>

2. 在CUDA函数中，使用以下代码来设置浮点舍入模式：

cudaDeviceSetLimit(cudaLimitDevRuntimeSyncDepth, 1);
cudaThreadSetLimit(cudaLimitDevRuntimePendingLaunchCount, 1);

unsigned int oldRoundMode, newRoundMode;
cudaDeviceGetLimit(&oldRoundMode, cudaLimitDevRuntimeRndMode);
newRoundMode = cudaRoundTrunc; // 设置为向零舍入模式
cudaDeviceSetLimit(cudaLimitDevRuntimeRndMode, newRoundMode);

3. 进行完成原子操作后，可以恢复浮点舍入模式为默认模式：

cudaDeviceSetLimit(cudaLimitDevRuntimeRndMode, oldRoundMode);

完整示例代码如下：

#include <cuda_fp16.h>
#include <stdio.h>

__global__ void test(float *data, int *index, float value) {
    unsigned int threadsPerBlock = blockDim.x * blockDim.y * blockDim.z;
    unsigned int threadNumInBlock = threadIdx.x + threadIdx.y * blockDim.x + threadIdx.z * blockDim.x * blockDim.y;
    unsigned int blockNum = blockIdx.x + blockIdx.y * gridDim.x + blockIdx.z * gridDim.x * gridDim.y;
    unsigned int threadNumInGrid = blockNum * threadsPerBlock + threadNumInBlock;

    if (threadNumInGrid < 100) {
        float oldValue = atomicAdd(data + index[threadNumInGrid], value);
        printf("Old Value: %.3f, New Value: %.3f\n", oldValue, oldValue + value);
    }
}

int main() {
    float *data;
    cudaMalloc(&data, sizeof(float) * 100);
    cudaMemset(data, 0, sizeof(float) * 100);

    int *index;
    cudaMalloc(&index, sizeof(int) * 100);
    for (int i = 0; i < 100; i++) {
        index[i] = i % 10;
    }

    cudaDeviceSetLimit(cudaLimitDevRuntimeSyncDepth, 1);
    cudaThreadSetLimit(cudaLimitDevRuntimePendingLaunchCount, 1);

    unsigned int oldRoundMode, newRoundMode;
    cudaDeviceGetLimit(&oldRoundMode,