m1 mem speedtest

memory_speeds2.cpp

#include <iostream>
#include <chrono>
#include <cstdint>
#include <unistd.h> // for sysctl

const int64_t ARRAY_SIZE = 1024 * 1024 * 1024; // 1024 MB
const int64_t REPETITIONS = 1000;

inline void flush_cache() {
    __builtin_arm_dsb(0b1111);
}

void measure_read_write_speed(int64_t* arr, int64_t size) {
    if (arr == nullptr) {
        std::cerr << "Invalid pointer" << std::endl;
        return;
    }
    
    auto start = std::chrono::high_resolution_clock::now();
    int64_t sum = 0;

    for (int64_t i = 0; i < REPETITIONS; ++i) {
        for (int64_t j = 0; j < size; ++j) {
            arr[j] = arr[j] + 1;
            sum += arr[j];
        }
        flush_cache();
    }

    auto end = std::chrono::high_resolution_clock::now();
    std::chrono::duration<double> elapsed = end - start;
    double time_per_operation = (elapsed.count() / (size * REPETITIONS)) * 1e9;

    double read_speed = (sizeof(int64_t) * size * REPETITIONS) / elapsed.count() / 1e9;
    double write_speed = (sizeof(int64_t) * size * REPETITIONS) / elapsed.count() / 1e9;

    std::cout << "Memory latency: " << time_per_operation << " ns" << std::endl;
    std::cout << "Read speed: " << read_speed << " GB/s" << std::endl;
    std::cout << "Write speed: " << write_speed << " GB/s" << std::endl;
}

int main() {
    int64_t* arr = new int64_t[ARRAY_SIZE];

    // Check if allocation succeeded
    if (arr == nullptr) {
        std::cerr << "Failed to allocate memory" << std::endl;
        return 1;
    }

    // Initialize array
    for (int64_t i = 0; i < ARRAY_SIZE; ++i) {
        arr[i] = i;
    }

    measure_read_write_speed(arr, ARRAY_SIZE);

    delete[] arr;
    return 0;
}