程序耗时测量工具

hyperfine

安装

sudo pacman -S hyperfine

示例

测量zsh的启动时间

hyperfine "zsh -i -c exit"

结果

Benchmark 1: zsh -i -c exit
  Time (mean ± σ):      19.9 ms ±   0.4 ms    [User: 15.0 ms, System: 6.9 ms]
  Range (min … max):    18.8 ms …  21.0 ms    138 runs

c++中map的重哈希和vector的内存移动耗时对比

重哈希rehash

// rehash.cpp
#include <unordered_map>
#include <string>

int main() {
  std::unordered_map<int, std::string> my_map;
  constexpr int N = 50000;
  for(int i = 0; i < N; ++i) {
    my_map[i] = "hello world hello world hello world \
                 hello world hello world hello world \
                 hello world hello world hello world \
                 hello world hello world hello world \
                 hello world hello world hello world \
                 hello world hello world hello world \
                 hello world hello world hello world \
                 hello world hello world hello world \
                 hello world hello world hello world ";
  }

  return 0;
}

内存移动recopy

// recopy.cpp
#include <vector>
#include <string>

int main() {
  std::vector<std::string> my_vec;
  constexpr int N = 50000;
  int a[N];
  for(int i = 0; i < N; ++i) {
    my_vec.emplace_back("hello world hello world hello world \
                         hello world hello world hello world \
                         hello world hello world hello world \
                         hello world hello world hello world \
                         hello world hello world hello world \
                         hello world hello world hello world \
                         hello world hello world hello world \
                         hello world hello world hello world \
                         hello world hello world hello world ");

    a[i] = i;
  }
  return 0;
}

运行hyperfine

hyperfine --warmup=5 "./rehash" "./recopy"

结果

Benchmark 1: ./rehash
  Time (mean ± σ):      21.5 ms ±   1.0 ms    [User: 13.5 ms, System: 7.8 ms]
  Range (min … max):    20.0 ms …  24.7 ms    126 runs

Benchmark 2: ./recopy
  Time (mean ± σ):      14.8 ms ±   0.9 ms    [User: 7.1 ms, System: 7.6 ms]
  Range (min … max):    13.4 ms …  17.1 ms    162 runs

Summary
  './recopy' ran
    1.45 ± 0.11 times faster than './rehash'

查看机器硬件信息

dmidecode

安装

sudo pacman -S dmidecode

支持的选项

点击 展开/收起 内容 

Type    Information
0   BIOS
1   System
2   Base Board
3   Chassis
4   Processor
5   Memory Controller
6   Memory Module
7   Cache
8   Port Connector
9   System Slots
10  On Board Devices
11  OEM Strings
12  System Configuration Options
13  BIOS Language
14  Group Associations
15  System Event Log
16  Physical Memory Array
17  Memory Device
18  32-bit Memory Error
19  Memory Array Mapped Address
20  Memory Device Mapped Address
21  Built-in Pointing Device
22  Portable Battery
23  System Reset
24  Hardware Security
25  System Power Controls
26  Voltage Probe
27  Cooling Device
28  Temperature Probe
29  Electrical Current Probe
30  Out-of-band Remote Access
31  Boot Integrity Services
32  System Boot
33  64-bit Memory Error
34  Management Device
35  Management Device Component
36  Management Device Threshold Data
37  Memory Channel
38  IPMI Device
39  Power Supply
40  Additional Information
41  Onboard Device

示例

sudo dmidecode -t memory

结果

点击 展开/收起 结果 

Handle 0x0022, DMI type 16, 23 bytes
Physical Memory Array
        Location: System Board Or Motherboard
        Use: System Memory
        Error Correction Type: None
        Maximum Capacity: 64 GB
        Error Information Handle: 0x0025
        Number Of Devices: 2

Handle 0x0023, DMI type 17, 92 bytes
Memory Device
        Array Handle: 0x0022
        Error Information Handle: 0x0026
        Total Width: 64 bits
        Data Width: 64 bits
        Size: 8 GB
        Form Factor: Row Of Chips
        Set: None
        Locator: DIMM 0
        Bank Locator: P0 CHANNEL A
        Type: DDR4
        Type Detail: Synchronous Unbuffered (Unregistered)
        Speed: 3200 MT/s
        Manufacturer: Samsung
        Serial Number: 00000000
        Asset Tag: Not Specified
        Part Number: M471A1G44AB0-CWE
        Rank: 1
        Configured Memory Speed: 3200 MT/s
        Minimum Voltage: 1.2 V
        Maximum Voltage: 1.2 V
        Configured Voltage: 1.2 V
        Memory Technology: DRAM
        Memory Operating Mode Capability: Volatile memory
        Firmware Version: Unknown
        Module Manufacturer ID: Bank 1, Hex 0xCE
        Module Product ID: Unknown
        Memory Subsystem Controller Manufacturer ID: Unknown
        Memory Subsystem Controller Product ID: Unknown
        Non-Volatile Size: None
        Volatile Size: 8 GB
        Cache Size: None
        Logical Size: None

Handle 0x0024, DMI type 17, 92 bytes
Memory Device
        Array Handle: 0x0022
        Error Information Handle: 0x0027
        Total Width: 64 bits
        Data Width: 64 bits
        Size: 8 GB
        Form Factor: Row Of Chips
        Set: None
        Locator: DIMM 0
        Bank Locator: P0 CHANNEL B
        Type: DDR4
        Type Detail: Synchronous Unbuffered (Unregistered)
        Speed: 3200 MT/s
        Manufacturer: Samsung
        Serial Number: 00000000
        Asset Tag: Not Specified
        Part Number: M471A1G44AB0-CWE
        Rank: 1
        Configured Memory Speed: 3200 MT/s
        Minimum Voltage: 1.2 V
        Maximum Voltage: 1.2 V
        Configured Voltage: 1.2 V
        Memory Technology: DRAM
        Memory Operating Mode Capability: Volatile memory
        Firmware Version: Unknown
        Module Manufacturer ID: Bank 1, Hex 0xCE
        Module Product ID: Unknown
        Memory Subsystem Controller Manufacturer ID: Unknown
        Memory Subsystem Controller Product ID: Unknown
        Non-Volatile Size: None
        Volatile Size: 8 GB
        Cache Size: None
        Logical Size: None

可以看到此电脑最多支持64G的内存，目前安装了2条8G的内存条

获取系统的CACHE_LINE

getconf LEVEL1_DCACHE_LINESIZE

结果

64

文本搜索工具ripgrep

替代GNU grep

用法

  1. 基础用法
rg 'keywords'
  1. 使用正则
rg -e '[0-9]\.'                 # 查找1., 2.这种形式的文本
rg -e '[0-9]\.' -g 'site/**'    # 在site目录及其子目录下查找1., 2.这种形式的文本
  1. 搜索单词
rg -e '\bkey\b'                 # 只查找key这个单词，相当于grep中的grep -E '\<key\>' -rn ./
rg -w 'key'
  1. 只查找指定文件类型
rg -t md '\bkey'                # 只在markdown文件中查找
rg -t md -t html '\bkey'        # 只在markdown和html文件中查找
rg -g '*{md, html}' -e '\bkey'  # 只在markdown和html文件中查找
  1. 过滤文件类型或文件夹
rg -T html -e '\bkey'           # 不查找html文件
rg -e '\bkey' -g '!site/*'      # 排除site目录
  1. 显示不包含关键词的行
rg -v 'keywords'