一、Bootchart简介

Bootchart官网http://www.bootchart.org，已经很久没有更新了。 Bootchart的目的是将启动阶段的性能可视化（Boot Process Performance Visualization）。具体做法是在启动阶段通过采样/proc文件系统来搜集启动阶段的信息（如CPU负载，进程信息，磁盘访问等），然后通过另外的工具将搜集到的数据以可视化的方式进行输出。 因此，bootchart分为两个部分：

• 采样程序bootchartd，系统启动后的第一个进程，采样并搜集启动过程中的/proc数据，启动完成后将采样数据压缩存放到/var/log/bootchart/bootlog.tgz文件中
• 外部工具pybootchartgui，处理bootlog.tgz文件，输出为图片
  
  • 对于PC，系统会在启动完成后自动生成bootlog.png文件
  • 对于嵌入式系统，需要将bootlog.tgz导出到PC上进行处理

下图是一个嵌入式系统上的bootchart输出的示例图片：
我在虚拟机上安装bootchart并抓取了启动过程数据，点这里查看Ubuntu 12.04启动后生成的图片。 在bootchart生成的图像中，可以清楚的看到启动过程中CPU负载、磁盘吞吐和各进程实时的情况。

二、Bootchart配置

Busybox从v1.17版本开始引入bootchartd。
相比PC，嵌入式系统没有完备的Bootchart工具，启动过程中采样的数据需要导出在PC上进行处理。 Busybox上通过执行make menuconfig配置bootchartd，具体位置如下： ygu@ubuntu:/opt/work/busybox$ make menuconfig Busybox Settings ---> --- Applets ... Init Utilities ---> [*] bootchartd [*] Compatible, bloated header [*] Support bootchartd.conf ... 默认设置打开所有bootchartd设置： 设置总共有3项：

• 选项[*] bootchartd，设置[BOOTCHARTD =y]，是bootchart功能开关
• 选项[*] Compatible, bloated header，设置[FEATURE_BOOTCHARTD_BLOATED_HEADER =y]，设置后bootchartd会生成一个包含类似如下信息的header文件：

version = 0.8 title = Boot chart for (none) (Thu Jan 1 00:01:05 UTC 1970) system.uname = Linux 3.3.8-4.0 #6 SMP Tue Nov 29 14:23:14 CST 2016 mips system.kernel.options = ubiroot init=/sbin/bootchartd ubi.mtd=rootfs rootfstype=ubifs root=ubi0:rootfs

• 选项[*] Support bootchartd.conf，设置[FEATURE_BOOTCHARTD_CONFIG_FILE =y]，设置后bootchartd启动时会尝试读取并解析配置文件/etc/bootchartd.conf，配置文件的格式类似如下：

# # supported options: # # Sampling period (in seconds) SAMPLE_PERIOD=0.2 # # not yet supported: # # tmpfs size # (32 MB should suffice for ~20 minutes worth of log data, but YMMV) TMPFS_SIZE=32m # Whether to enable and store BSD process accounting information. The # kernel needs to be configured to enable v3 accounting # (CONFIG_BSD_PROCESS_ACCT_V3). accton from the GNU accounting utilities # is also required. PROCESS_ACCOUNTING="no" # Tarball for the various boot log files BOOTLOG_DEST=/var/log/bootchart.tgz # Whether to automatically stop logging as the boot process completes. # The logger will look for known processes that indicate bootup completion # at a specific runlevel (e.g. gdm-binary, mingetty, etc.). AUTO_STOP_LOGGER="yes" # Whether to automatically generate the boot chart once the boot logger # completes. The boot chart will be generated in $AUTO_RENDER_DIR. # Note that the bootchart package must be installed. AUTO_RENDER="no" 从busybox中bootchartd实现的代码来看，仅支持SAMPLE_PERIOD和SAMPLE_PERIOD两个选项。当然，也可以不用设置/etc/bootchartd.conf而使用代码中默认的设置。

三、Bootchart运行

bootchart的帮助信息： Usage: bootchartd start [PROG ARGS]|stop|init Options: start: start background logging; with PROG, run PROG, then kill logging with USR1 stop: send USR1 to all bootchartd processes init: start background logging; stop when getty/xdm is seen (for init scripts) Under PID 1: start background logging, then execute $bootchart_init, /init, /sbin/init This makes it possible to start bootchartd even before init by booting kernel with: init=/sbin/bootchartd bootchart_init=/path/to/regular/init 从帮助信息可见bootchartd有两个用途：

• linux启动时运行用于采样linux启动过程中的各项数据
• 启动完成后运行，用于监测系统或指定应用程序

1. linux启动时运行

这是使用最多的方式，在linux启动的命令行中指定/sbin/bootchartd为init进程。

• 带initramfs的系统，需要在命令行指定rdinit
rdinit=/sbin/bootchartd
• 非initramfs的系统，需要在命令行指定init
init=/sbin/bootchartd

linux启动中，会用/sbin/bootchartd创建第一个进程，然后在bootchartd中再fork一个真正的init进程。如果在启动的同时通过命令行指定了bootchart_init参数，则用这个参数指定的程序用于fork生成的init进程，否则依次使用默认的/init或/sbin/init作为init进程。如： init=/sbin/bootchartd bootchart_init=/path/to/regular/init 以下是我在博通7583参考平台上使用带文件系统的kernel启动的log: CFE> CFE> boot -z -elf 192.168.1.95:7584a0/vmlinuz-initrd-7584a0 'rdinit=/sbin/bootchartd quiet' Loader:elf Filesys:tftp Dev:eth0 File:192.168.1.95:7584a0/vmlinuz-initrd-7584a0 Options:rdinit=/sbin/bootchartd quiet Loading: 0x80001000/11957248 0x80b68400/110224 Entry address is 0x8045f360 Closing network. Starting program at 0x8045f360 Linux version 3.3.8-4.0 (ygu@fs-ygu) (gcc version 4.5.4 (Broadcom stbgcc-4.5.4-2.9) ) #5 SMP Tue Nov 29 14:23:04 CST 2016 Fetching vars from bootloader... found 14 vars. Options: moca=0 sata=1 pcie=0 usb=1 Using 512 MB + 0 MB RAM (from CFE) bootconsole [early0] enabled CPU revision is: 0002a065 (Broadcom BMIPS4380) FPU revision is: 00130001 Determined physical RAM map: memory: 10000000 @ 00000000 (usable) memory: 10000000 @ 20000000 (usable) No PHY detected, not registering interface:1 starting pid 429, tty '': '/etc/init.d/rcS' Mounting virtual filesystems Starting mdev * WARNING: THIS STB CONTAINS GPLv3 SOFTWARE * GPLv3 programs must be removed in order to enable security. * See: http://www.gnu.org/licenses/gpl-faq.html#Tivoization Configuring eth0 interface Configuring lo interface Starting network services starting pid 459, tty '': '/bin/cttyhack /bin/sh -l' # # shell-init: error retrieving current directory: getcwd: cannot access parent directories: Success # # ls -lh /var/log/ -rw-r--r-- 1 root root 28.9K Jan 1 00:01 bootlog.tgz # 可以看到，系统启动完成后会在/var/log目录下生成bootlog.tgz文件（PC上采样的数据文件位于/var/log/bootchartd/目录下）。将文件/var/log/bootlog.tgz复制到PC上备用。 在主机上安装bootchart工具，安装的同时还会安装pybootchartgui用于将采集的数据转换为图片。 ygu@ubuntu:~$ sudo apt-get install bootchart [sudo] password for ygu: Reading package lists... Done Building dependency tree Reading state information... Done The following NEW packages will be installed: bootchart 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. Need to get 0 B/11.0 kB of archives. After this operation, 127 kB of additional disk space will be used. Selecting previously unselected package bootchart. (Reading database ... 170788 files and directories currently installed.) Unpacking bootchart (from .../bootchart_0.90.2-8ubuntu1_i386.deb) ... Processing triggers for ureadahead ... Setting up bootchart (0.90.2-8ubuntu1) ... update-initramfs: Generating /boot/initrd.img-3.13.0-32-generic ygu@ubuntu:~$ scp ygu@192.168.1.95:/opt/bootchartd/bootlog.tgz work/bootchart bootlog.tgz 100% 29KB 29.3KB/s 00:00 ygu@ubuntu:~$ cd work/bootchart 使用pybootchartgui处理bootlog.tgz： ygu@ubuntu:~/work/bootchart$ ls -lh total 32K -rw-r--r-- 1 ygu ygu 30K Dec 1 10:28 bootlog.tgz ygu@ubuntu:~/work/bootchart$ ygu@ubuntu:~/work/bootchart$ pybootchartgui bootlog.tgz parsing 'bootlog.tgz' parsing 'header' parsing 'proc_diskstats.log' parsing 'proc_ps.log' warning: no parent for pid '2' with ppid '0' parsing 'proc_stat.log' merged 0 logger processes pruned 29 process, 0 exploders, 0 threads, and 0 runs False Traceback (most recent call last): File "/usr/bin/pybootchartgui", line 23, in <module> sys.exit(main()) File "/usr/lib/pymodules/python2.7/pybootchartgui/main.py", line 137, in main render() File "/usr/lib/pymodules/python2.7/pybootchartgui/main.py", line 128, in render batch.render(writer, res, options, filename) File "/usr/lib/pymodules/python2.7/pybootchartgui/batch.py", line 41, in render draw.render(ctx, options, *res) File "/usr/lib/pymodules/python2.7/pybootchartgui/draw.py", line 256, in render curr_y = draw_header(ctx, headers, off_x, duration) File "/usr/lib/pymodules/python2.7/pybootchartgui/draw.py", line 340, in draw_header txt = headertitle + ': ' + mangle(headers.get(headerkey)) TypeError: cannot concatenate 'str' and 'NoneType' objects ygu@ubuntu:~/work/bootchart$ 如上，由于Ubuntu版本的pybootchartgui不能解析busybox上的bootchart数据，所以这里出现了错误，需要用另外一个版本bootchart2的工具来处理。 用git下载bootchart2后需要执行make后才能使用pybootchartgui： ygu@ubuntu:~/work/bootchart$ git clone https://github.com/xrmx/bootchart.git Cloning into 'bootchart'... remote: Counting objects: 2560, done. remote: Total 2560 (delta 0), reused 0 (delta 0), pack-reused 2560 Receiving objects: 100% (2560/2560), 1.79 MiB | 228 KiB/s, done. Resolving deltas: 100% (1600/1600), done. ygu@ubuntu:~/work/bootchart$ cd bootchart/ ygu@ubuntu:~/work/bootchart/bootchart$ make cc -g -Wall -O0 -pthread -DEARLY_PREFIX='""' -DLIBDIR='"/lib"' -DPKGLIBDIR='"/lib/bootchart"' -DPROGRAM_PREFIX='""' -DPROGRAM_SUFFIX='""' -DVERSION='"0.14.8"' -c collector/collector.c -o collector/collector.o ... cc -g -Wall -O0 -pthread -Icollector -o bootchart-collector collector/collector.o collector/output.o collector/tasks.o collector/tasks-netlink.o collector/dump.o sed -s -e "s:@LIBDIR@:/lib:g" -e "s:@PKGLIBDIR@:/lib/bootchart:" -e "s:@PROGRAM_PREFIX@::" -e "s:@PROGRAM_SUFFIX@::" -e "s:@EARLY_PREFIX@::" -e "s:@VER@:0.14.8:" bootchartd.in > bootchartd ... sed -s -e "s:@LIBDIR@:/lib:g" -e "s:@PKGLIBDIR@:/lib/bootchart:" -e "s:@PROGRAM_PREFIX@::" -e "s:@PROGRAM_SUFFIX@::" -e "s:@EARLY_PREFIX@::" -e "s:@VER@:0.14.8:" pybootchartgui/main.py.in > pybootchartgui/main.py ygu@ubuntu:~/work/bootchart/bootchart$ 如果不编译，直接调用pybootchartgui会出现找不到main函数的错误： ygu@ubuntu:~/work/bootchart$ ./bootchart/pybootchartgui.py bootlog.tgz Traceback (most recent call last): File "./bootchart/pybootchartgui.py", line 20, in <module> from pybootchartgui.main import main ImportError: No module named main ygu@ubuntu:~/work/bootchart$ 编译完成后，再次调用pybootchartgui.py处理bootlog.tgz： ygu@ubuntu:~/work/bootchart$ ./bootchart/pybootchartgui.py bootlog.tgz parsing 'bootlog.tgz' parsing 'header' parsing 'proc_diskstats.log' parsing 'proc_ps.log' parsing 'proc_stat.log' merged 0 logger processes pruned 29 process, 0 exploders, 0 threads, and 0 runs bootchart written to 'bootchart.png' ygu@ubuntu:~/work/bootchart$ ls -lh total 96K drwxr-xr-x 6 ygu ygu 4.0K Dec 1 10:45 bootchart -rw-rw-r-- 1 ygu ygu 59K Dec 1 10:46 bootchart.png -rw-r--r-- 1 ygu ygu 30K Dec 1 10:28 bootlog.tgz ygu@ubuntu:~/work/bootchart$ 将采集的数据转换为图片bootchart.png了，如下：
由于这里整个linux系统启动的任务比较简单，所以从bootchart.png上可见的任务也较少，这里寄希望于bootchart的结果来进行启动时间优化还是有些难度。

2. 监测系统或应用程序的运行情况

用于监测运行情况时需要给bootchartd指定参数，start参数开始监测，stop参数停止监测。 不过，系统启动后可以监测的手段较多，bootchartd工具并不是最优选择，非本文的介绍重点，暂略。

四、Bootchartd源码分析

busyboxinitootchartd.c：

• bootchartd_main

/* bootchart的main函数入口 */ int bootchartd_main(int argc UNUSED_PARAM, char **argv) { unsigned sample_period_us; pid_t parent_pid, logger_pid; smallint cmd; int process_accounting; /* bootchart的命令类型 */ enum { CMD_STOP = 0, /* STOP命令，用于'bootchart stop' */ CMD_START, /* START命令， 用于'bootchart start [PROG ARGS]' */ CMD_INIT, /* INIT命令， 用于'bootchart init'，实际上并没有使用 */ CMD_PID1, /* used to mark pid 1 case */ /* 作为linux启动的init进程时使用，init=/sbin/bootchartd */ }; INIT_G(); /* 获取当前进程pid，init进程的pid为1 */ parent_pid = getpid(); if (argv[1]) { /* 检查bootchartd命令参数 */ cmd = index_in_strings("stop