alignperf.cpp

//
//  main.cpp
//  alignperf
//
//  Created by LARRYHOU on 2021/5/13.
//

#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <map>

#include <chrono>

#define DISK_PAGE_SIZE (4<<10)

std::vector<uint64_t> benchmark(std::string filename, std::ios::off_type offset, int repeat)
{
    std::vector<uint64_t> records;
    
    std::fstream fs;
    fs.open(filename, std::ios::in);
    fs.seekg(0, std::ios::end);
    auto length = fs.tellg();
    
    char block[DISK_PAGE_SIZE];
    
    while (repeat--)
    {
        fs.clear();
        fs.seekg(offset);
        
        auto stime = std::chrono::high_resolution_clock::now();
        
        auto remain = length;
        while (remain > 0)
        {
            auto size = std::min<uint64_t>(DISK_PAGE_SIZE, remain - fs.tellg());
            fs.read(block, size);
            remain -= size;
        }
        
        auto etime = std::chrono::high_resolution_clock::now();
        records.push_back(std::chrono::duration_cast<std::chrono::duration<uint64_t, std::nano>>(etime - stime).count());
    }
    
    fs.close();
    return records;
}

int main(int argc, const char * argv[])
{
    for (auto i = 1; i < argc; i++)
    {
        std::string filename(argv[i]);
        std::cout << filename << std::endl;
        
        auto offset = 1;
        std::vector<int> cases;
        while (offset <= DISK_PAGE_SIZE)
        {
            cases.push_back(offset);
            offset <<= 1;
        }
        
        for (auto i = 0; i < 10; i++)
        {
            cases.push_back(rand() % DISK_PAGE_SIZE + 1);
        }
        
        for (auto i = 0; i < cases.size(); i++)
        {
            offset = cases[i];
            auto stats = benchmark(filename, offset, 3);
            uint64_t sum = 0;
            for (auto iter = stats.begin(); iter != stats.end(); iter++) { sum += *iter; }
            auto mean = sum / stats.size();
            
            printf("  %4d %lld=(", offset, mean);
            for (auto iter = stats.begin(); iter != stats.end(); iter++) {
                std::cout << *iter << ',';
            }
            std::cout << '\b' << ')' << std::endl;
            
            offset <<= 1;
        }
    }
    
    return 0;
}

Android.mk

LOCAL_PATH :=$(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := alignperf
LOCAL_SRC_FILES := alignperf.cpp
include $(BUILD_EXECUTABLE)

Application.mk

APP_ABI := x86 arm64-v8a
APP_PLATFORM := android-21
APP_STL := c++_static
APP_CPPFLAGS := -std=c++11
APP_BUILD_SCRIPT := Android.mk

build.sh

NDK_PROJECT_PATH=. ~/Library/Android/sdk/ndk/20.0.5594570/ndk-build NDK_APPLICATION_MK=Application.mk