Linux内核进修008——进程治理(四)_过程_内核

进程家族树

Unix系统的进程之间存在一个明显的继续关系，所有的进程都是PID为1的init进程的后代。
内核在系统启动的末了阶段启动init进程，然后init进程读取系统的初始化脚本并实行其他的干系程序，终极完成系统启动的全体过程。

在Linux系统中有三个分外的进程，idle进程(PID=0)，init进程(PID=1)和kthreadd(PID=2)。

idle进程由系统创建，运行在内核态，其PID=0。
idle前身是系统创建的第一个进程，也是唯一一个没有通过fork()产生的进程。

init进程由idle通过kernel_thread创建，在内核空间完成初始化后，加载init程序(运行在用户空间)。
Linux中的所有运行在用户空间的进程都是由init创建并运行的，在系统启动完成后，init将变为守护进程监视其他进程并卖力处理孤儿进程(进程还未结束其父进程就已经结束的进程)。

kthread进程由idle通过kernel_thread()创建，并始终运行在内核空间，卖力所有内核线程的调度和管理。
kthread进程卖力管理和调度其他内核线程，所有的内核线程都直接或间接以kthread为父进程。

我们利用ps和pstree来不雅观察一下CentOS6.10系统上的进程。

在终端实行ps -e得到以下结果：

ps -e # 输出如下： PID TTY TIME CMD 1 ? 00:00:01 init 2 ? 00:00:00 kthreadd 3 ? 00:00:00 migration/0 4 ? 00:00:00 ksoftirqd/0 5 ? 00:00:00 stopper/0 6 ? 00:00:00 watchdog/0 7 ? 00:00:00 migration/1 8 ? 00:00:00 stopper/1 9 ? 00:00:00 ksoftirqd/1 10 ? 00:00:00 watchdog/1 11 ? 00:00:00 migration/2 12 ? 00:00:00 stopper/2 13 ? 00:00:00 ksoftirqd/2 14 ? 00:00:00 watchdog/2 15 ? 00:00:00 migration/3 16 ? 00:00:00 stopper/3 17 ? 00:00:00 ksoftirqd/3 18 ? 00:00:00 watchdog/3 19 ? 00:00:03 events/0 20 ? 00:00:00 events/1 21 ? 00:00:00 events/2 22 ? 00:00:00 events/3 23 ? 00:00:00 events/0 24 ? 00:00:00 events/1 25 ? 00:00:00 events/2 26 ? 00:00:00 events/3 27 ? 00:00:00 events_long/0 28 ? 00:00:00 events_long/1 29 ? 00:00:00 events_long/2 30 ? 00:00:00 events_long/3 31 ? 00:00:00 events_power_ef 32 ? 00:00:00 events_power_ef 33 ? 00:00:00 events_power_ef 34 ? 00:00:00 events_power_ef 35 ? 00:00:00 cgroup 36 ? 00:00:00 khelper 37 ? 00:00:00 netns 38 ? 00:00:00 async/mgr 39 ? 00:00:00 pm 40 ? 00:00:00 sync_supers 41 ? 00:00:00 bdi-default 42 ? 00:00:00 kintegrityd/0 43 ? 00:00:00 kintegrityd/1 44 ? 00:00:00 kintegrityd/2 45 ? 00:00:00 kintegrityd/3 46 ? 00:00:00 kblockd/0 47 ? 00:00:00 kblockd/1 48 ? 00:00:00 kblockd/2 49 ? 00:00:00 kblockd/3 50 ? 00:00:00 kacpid 51 ? 00:00:00 kacpi_notify 52 ? 00:00:00 kacpi_hotplug 53 ? 00:00:00 ata_aux 54 ? 00:00:00 ata_sff/0 55 ? 00:00:00 ata_sff/1 56 ? 00:00:00 ata_sff/2 57 ? 00:00:00 ata_sff/3 58 ? 00:00:00 ksuspend_usbd 59 ? 00:00:00 khubd 60 ? 00:00:00 kseriod 61 ? 00:00:00 md/0 62 ? 00:00:00 md/1 63 ? 00:00:00 md/2 64 ? 00:00:00 md/3 65 ? 00:00:00 md_misc/0 66 ? 00:00:00 md_misc/1 67 ? 00:00:00 md_misc/2 68 ? 00:00:00 md_misc/3 69 ? 00:00:00 linkwatch 72 ? 00:00:00 khungtaskd 73 ? 00:00:00 lru-add-drain/0 74 ? 00:00:00 lru-add-drain/1 75 ? 00:00:00 lru-add-drain/2 76 ? 00:00:00 lru-add-drain/3 77 ? 00:00:00 kswapd0 78 ? 00:00:00 ksmd 79 ? 00:00:00 khugepaged 80 ? 00:00:00 aio/0 81 ? 00:00:00 aio/1 82 ? 00:00:00 aio/2 83 ? 00:00:00 aio/3 84 ? 00:00:00 crypto/0 85 ? 00:00:00 crypto/1 86 ? 00:00:00 crypto/2 87 ? 00:00:00 crypto/3 94 ? 00:00:00 kthrotld/0 95 ? 00:00:00 kthrotld/1 96 ? 00:00:00 kthrotld/2 97 ? 00:00:00 kthrotld/3 98 ? 00:00:00 pciehpd 100 ? 00:00:00 kpsmoused 101 ? 00:00:00 usbhid_resumer 102 ? 00:00:00 deferwq 135 ? 00:00:00 kdmremove 136 ? 00:00:00 kstriped 316 ? 00:00:00 scsi_eh_0 317 ? 00:00:00 scsi_eh_1 403 ? 00:00:00 mpt_poll_0 404 ? 00:00:00 mpt/0 405 ? 00:00:00 scsi_eh_2 464 ? 00:00:00 kdmflush 466 ? 00:00:00 kdmflush 532 ? 00:00:00 jbd2/dm-0-8 533 ? 00:00:00 ext4-dio-unwrit 639 ? 00:00:00 udevd 806 ? 00:00:00 vmmemctl 1241 ? 00:00:00 kdmflush 1287 ? 00:00:00 jbd2/sda1-8 1288 ? 00:00:00 ext4-dio-unwrit 1289 ? 00:00:00 jbd2/dm-2-8 1290 ? 00:00:00 ext4-dio-unwrit 1312 ? 00:00:00 flush-253:0 1343 ? 00:00:00 kauditd 1402 ? 00:00:00 ib_addr 1407 ? 00:00:00 infiniband/0 1408 ? 00:00:00 infiniband/1 1409 ? 00:00:00 infiniband/2 1410 ? 00:00:00 infiniband/3 1419 ? 00:00:00 ib_mcast 1424 ? 00:00:00 iw_cm_wq 1429 ? 00:00:00 ib_cm/0 1430 ? 00:00:00 ib_cm/1 1431 ? 00:00:00 ib_cm/2 1432 ? 00:00:00 ib_cm/3 1437 ? 00:00:00 rdma_cm 1458 ? 00:00:00 ipoib_flush 1651 ? 00:00:00 auditd 1685 ? 00:00:00 rsyslogd 1719 ? 00:00:00 irqbalance 1744 ? 00:00:00 rpcbind 1764 ? 00:00:00 dbus-daemon 1779 ? 00:00:00 NetworkManager 1786 ? 00:00:00 modem-manager 1802 ? 00:00:00 rpc.statd 1840 ? 00:00:00 cupsd 1843 ? 00:00:00 wpa_supplicant 1875 ? 00:00:00 acpid 1887 ? 00:00:00 hald 1888 ? 00:00:00 hald-runner 1930 ? 00:00:00 hald-addon-inpu 1953 ? 00:00:00 hald-addon-acpi 1962 ? 00:00:00 automount 2127 ? 00:00:00 sshd 2138 ? 00:00:00 ntpd 2225 ? 00:00:00 master 2236 ? 00:00:00 pickup 2237 ? 00:00:00 qmgr 2243 ? 00:00:06 vmtoolsd 2296 ? 00:00:00 abrtd 2330 ? 00:00:00 ksmtuned 2343 ? 00:00:00 crond 2358 ? 00:00:00 atd 2375 ? 00:00:00 libvirtd 2491 ? 00:00:00 dnsmasq 2493 ? 00:00:00 certmonger 2521 ? 00:00:00 gdm-binary 2528 tty2 00:00:00 mingetty 2530 tty3 00:00:00 mingetty 2532 tty4 00:00:00 mingetty 2534 tty5 00:00:00 mingetty 2536 tty6 00:00:00 mingetty 2544 ? 00:00:00 udevd 2545 ? 00:00:00 udevd 2589 ? 00:00:00 gdm-simple-slav 2594 tty1 00:00:09 Xorg 2648 ? 00:00:00 console-kit-dae 2718 ? 00:00:00 dbus-launch 2724 ? 00:00:00 devkit-power-da 2767 ? 00:00:00 polkitd 2776 ? 00:00:00 rtkit-daemon 2783 ? 00:00:00 gdm-session-wor 2793 ? 00:00:00 gnome-keyring-d 2803 ? 00:00:00 gnome-session 2811 ? 00:00:00 dbus-launch 2812 ? 00:00:00 dbus-daemon 2887 ? 00:00:00 gconfd-2 2891 ? 00:00:00 gnome-settings- 2901 ? 00:00:00 gvfsd 2906 ? 00:00:00 seahorse-daemon 2908 ? 00:00:00 metacity 2912 ? 00:00:07 pulseaudio 2913 ? 00:00:00 gnome-panel 2924 ? 00:00:00 gconf-helper 2926 ? 00:00:01 nautilus 2932 ? 00:00:00 bonobo-activati 2937 ? 00:00:00 wnck-applet 2940 ? 00:00:00 trashapplet 2942 ? 00:00:00 gvfs-gdu-volume 2944 ? 00:00:00 udisks-daemon 2945 ? 00:00:00 udisks-daemon 2951 ? 00:00:00 gvfsd-trash 2954 ? 00:00:00 nm-applet 2955 ? 00:00:05 vmtoolsd 2956 ? 00:00:00 restorecond 2957 ? 00:00:00 polkit-gnome-au 2960 ? 00:00:00 gvfs-afc-volume 2961 ? 00:00:00 gnome-volume-co 2967 ? 00:00:00 abrt-applet 2968 ? 00:00:00 python 2970 ? 00:00:00 im-settings-dae 2993 ? 00:00:00 gnome-power-man 3012 ? 00:00:00 bluetooth-apple 3019 ? 00:00:00 gpk-update-icon 3039 ? 00:00:00 gdu-notificatio 3058 ? 00:00:00 gnome-screensav 3131 ? 00:00:00 gvfs-gphoto2-vo 3145 ? 00:00:00 gconf-im-settin 3154 ? 00:00:00 gnote 3156 ? 00:00:00 clock-applet 3158 ? 00:00:00 gdm-user-switch 3160 ? 00:00:00 notification-ar 3183 ? 00:00:00 gvfsd-metadata 3189 ? 00:00:00 gvfsd-burn 3197 ? 00:00:02 gnome-terminal 3198 ? 00:00:00 gnome-pty-helpe 3224 ? 00:00:00 dhclient 3344 pts/1 00:00:00 bash 3775 ? 00:00:00 flush-253:2 3810 ? 00:00:00 packagekitd 3834 ? 00:00:00 anacron 4011 ? 00:00:00 sleep 4012 pts/1 00:00:00 ps 4013 pts/1 00:00:00 xsel

pstree能够帮助我们展示进程树，更直不雅观地不雅观察进程间的关系。

不雅观察用户空间进程树：pstree 1

pstree 1# 输出如下：init-+-NetworkManager-+-dhclient | `-{NetworkManager} |-abrtd |-acpid |-anacron |-atd |-auditd---{auditd} |-automount---4[{automount}] |-bonobo-activati---{bonobo-activat} |-certmonger |-clock-applet |-console-kit-dae---63[{console-kit-da}] |-crond |-cupsd |-2[dbus-daemon---{dbus-daemon}] |-2[dbus-launch] |-devkit-power-da |-dnsmasq |-gconf-im-settin |-gconfd-2 |-gdm-binary-+-gdm-simple-slav-+-Xorg---4[{Xorg}] | | |-gdm-session-wor-+-gnome-session-+-abrt-applet | | | | |-bluetooth-apple | | | | |-gdu-notificatio | | | | |-gnome-panel | | | | |-gnome-power-man | | | | |-gnome-volume-co | | | | |-gpk-update-icon | | | | |-metacity---{metacity} | | | | |-nautilus | | | | |-nm-applet | | | | |-polkit-gnome-au | | | | |-python | | | | |-restorecond | | | | `-{gnome-session} | | | `-{gdm-session-wo} | | `-{gdm-simple-sla} | `-{gdm-binary} |-gdm-user-switch |-gnome-keyring-d---2[{gnome-keyring-}] |-gnome-screensav |-gnome-settings----{gnome-settings} |-gnome-terminal-+-bash---man---sh---sh---less | |-bash-+-pstree | | `-xsel | |-gnome-pty-helpe | `-{gnome-terminal} |-gnote |-gvfs-afc-volume---{gvfs-afc-volum} |-gvfs-gdu-volume |-gvfs-gphoto2-vo |-gvfsd |-gvfsd-burn |-gvfsd-metadata |-gvfsd-trash |-hald-+-hald-runner-+-hald-addon-acpi | | `-hald-addon-inpu | `-{hald} |-im-settings-dae |-irqbalance |-ksmtuned---sleep |-libvirtd---10[{libvirtd}] |-master-+-pickup | `-qmgr |-5[mingetty] |-modem-manager |-notification-ar |-ntpd |-polkitd |-pulseaudio-+-gconf-helper | `-2[{pulseaudio}] |-rpc.statd |-rpcbind |-rsyslogd---3[{rsyslogd}] |-rtkit-daemon---2[{rtkit-daemon}] |-seahorse-daemon |-sshd |-trashapplet |-udevd---2[udevd] |-udisks-daemon-+-udisks-daemon | `-{udisks-daemon} |-vmtoolsd---{vmtoolsd} |-vmtoolsd |-wnck-applet `-wpa_supplicant

不雅观察内核空间进程树：pstree 2

pstree 2# 输出如下：kthreadd-+-aio/0 |-aio/1 |-aio/2 |-aio/3 |-async/mgr |-ata_aux |-ata_sff/0 |-ata_sff/1 |-ata_sff/2 |-ata_sff/3 |-bdi-default |-cgroup |-crypto/0 |-crypto/1 |-crypto/2 |-crypto/3 |-deferwq |-2[events/0] |-2[events/1] |-2[events/2] |-2[events/3] |-events_long/0 |-events_long/1 |-events_long/2 |-events_long/3 |-4[events_power_ef] |-3[ext4-dio-unwrit] |-flush-253:0 |-flush-253:2 |-ib_addr |-ib_cm/0 |-ib_cm/1 |-ib_cm/2 |-ib_cm/3 |-ib_mcast |-infiniband/0 |-infiniband/1 |-infiniband/2 |-infiniband/3 |-ipoib_flush |-iw_cm_wq |-jbd2/dm-0-8 |-jbd2/dm-2-8 |-jbd2/sda1-8 |-kacpi_hotplug |-kacpi_notify |-kacpid |-kauditd |-kblockd/0 |-kblockd/1 |-kblockd/2 |-kblockd/3 |-3[kdmflush] |-kdmremove |-khelper |-khubd |-khugepaged |-khungtaskd |-kintegrityd/0 |-kintegrityd/1 |-kintegrityd/2 |-kintegrityd/3 |-kpsmoused |-kseriod |-ksmd |-ksoftirqd/0 |-ksoftirqd/1 |-ksoftirqd/2 |-ksoftirqd/3 |-kstriped |-ksuspend_usbd |-kswapd0 |-kthrotld/0 |-kthrotld/1 |-kthrotld/2 |-kthrotld/3 |-linkwatch |-lru-add-drain/0 |-lru-add-drain/1 |-lru-add-drain/2 |-lru-add-drain/3 |-md/0 |-md/1 |-md/2 |-md/3 |-md_misc/0 |-md_misc/1 |-md_misc/2 |-md_misc/3 |-migration/0 |-migration/1 |-migration/2 |-migration/3 |-mpt/0 |-mpt_poll_0 |-netns |-pciehpd |-pm |-rdma_cm |-scsi_eh_0 |-scsi_eh_1 |-scsi_eh_2 |-stopper/0 |-stopper/1 |-stopper/2 |-stopper/3 |-sync_supers |-usbhid_resumer |-vmmemctl |-watchdog/0 |-watchdog/1 |-watchdog/2 `-watchdog/3init进程

我们可以在CentOS的/sbin目录下创造init的可实行文件，通过rpm -qf init查询出其所属的软件包为upstart-0.6.5-17.el6.x86_64。

接着，通过rpm info upstart查询其干系信息，得到以下结果：

Loaded plugins: fastestmirror, refresh-packagekit, securityLoading mirror speeds from cached hostfile base: mirrors.nju.edu.cn epel: mirrors.aliyun.com extras: mirrors.163.com updates: mirrors.163.comInstalled PackagesName : upstartArch : x86_64Version : 0.6.5Release : 17.el6Size : 554 kRepo : installedFrom repo : anaconda-CentOS-201806291108.x86_64Summary : An event-driven init systemURL : http://upstart.ubuntu.comLicense : GPLv2 and LGPLv2+Description : Upstart is an event-based replacement for the /sbin/init daemon : which handles starting of tasks and services during boot, stopping : them during shutdown and supervising them while the system is : running.

待补充。
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