使用cache加快编译速度的命令详解

目录

• Ubuntu 安装ccache
• 使用libzmq测试ccache

Ubuntu 安装ccache

1. sudo apt-get install ccache
2. 安装完后确认安装执行which ccache

$ which ccache
/usr/bin/ccache

3.在 ~/.bashrc 或者 ~/.zshrc文件内追加以下内容

# ccache
export USE_CCACHE=1
export CCACHE_SLOPPINESS=file_macro,include_file_mtime,time_macros
export CCACHE_UMASK=002

source /.bashrc或者/.zshrc
4. ccache默认设置的5G磁盘空间，正常来说够用，如果担心不够可以改大一些,
ccache -M 30G
5. 通过版本确认安装成功

$ ccache --version
ccache version 3.4.1
Copyright (C) 2002-2007 Andrew Tridgell
Copyright (C) 2009-2018 Joel Rosdahl

6.可以通过ccache -s查看当前配置

cache directory                     /home/username/.ccache
primary config                      /home/username/.ccache/ccache.conf
secondary config      (readonly)    /etc/ccache.conf
stats zero time                     Fri Jul 22 16:15:40 2022
cache hit (direct)                  4186
cache hit (preprocessed)             875
cache miss                          1069
cache hit rate                      82.56 %
called for link                      653
cleanups performed                     0
files in cache                      3209
cache size                          159.3 MB
max cache size                      30.0 GB

使用libzmq测试ccache

1.通过github下载 libzmq的源码

$ git clone  https://github.com/zeromq/libzmq.git
Cloning into 'libzmq'...
remote: Enumerating objects: 43791, done.
remote: Counting objects: 100% (36/36), done.
remote: Compressing objects: 100% (28/28), done.
remote: Total 43791 (delta 11), reused 24 (delta 8), pack-reused 43755
Receiving objects: 100% (43791/43791), 21.91 MiB | 1.03 MiB/s, done.
Resolving deltas: 100% (31951/31951), done.

2.在 libzmq目录内建立 build目录

3.修改CMakeLists.txt, '+'后面的代表新增

──────┬───────────────────────────────────────────────────────────────────────────────────────
       │ File: CMakeLists.txt
───────┼──────────────────────────────────────────────────────────────────────────────────────
   1   │ # CMake build script for ZeroMQ
   2   │ project(ZeroMQ)
   3   │
   4   │ if(${CMAKE_SYSTEM_NAME} STREQUAL Darwin)
   5   │   cmake_minimum_required(VERSION 3.0.2)
   6   │ else()
   7   │   cmake_minimum_required(VERSION 2.8.12)
   8   │ endif()
   9   │
  10 + │ find_program(CCACHE_FOUND ccache)
  11 + │ if(CCACHE_FOUND)
  12 + │     set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE ccache)
  13 + │     set_property(GLOBAL PROPERTY RULE_LAUNCH_LINK ccache)
  14 + │     message(STATUS "use ccache")
  15 + │ endif(CCACHE_FOUND)
  16 + │
  17   │ include(CheckIncludeFiles)

4.在build目录执行cmake ..
打印显示 -- use ccache 表示启用ccache，但需要注意的事，每个项目在第一次启用ccache时，不会加快编译速度，而是把编译缓存保存到 /home/username/.ccache目录，供以后编译使用

$ cmake ..
-- The C compiler identification is GNU 7.5.0
-- The CXX compiler identification is GNU 7.5.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- use ccache
-- Looking for pthread.h
-- Looking for pthread.h - found
-- Looking for pthread_create
-- Looking for pthread_create - not found
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - found
-- Found Threads: TRUE
...

5.使用 /usr/bin/time命令来记录编译耗费的时间

/usr/bin/time make -j3
result:
48.79user 14.25system 0:21.60elapsed 291%CPU (0avgtext+0avgdata 176036maxresident)k
0inputs+282248outputs (0major+2406923minor)pagefaults 0swaps

6.rm -rf * 删除build目录内的所有文件

7.重新 cmake ..

8.使用 /usr/bin/time命令来记录编译耗费的时间

/usr/bin/time make -j3
result:
2.78user 2.42system 0:02.15elapsed 241%CPU (0avgtext+0avgdata 23736maxresident)k
0inputs+21744outputs (0major+232849minor)pagefaults 0swaps

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