linux 定时休眠

最近公司规定晚上走人后必须关闭电脑,但是像我们这样的人,经常会忘记了关闭电脑,而且关闭电脑之后再恢复工作环境也是件挺麻烦的事情,无奈之下只能折腾一下,让linux定时休眠了。

休眠的类型

目前大概由三种类型的休眠:

suspend(suspend to RAM)

指的是除了内存以外的大部分机器部件都进入断电状态。 这种休眠状态恢复速度特别快,但由于内存中的数据并没有被保存下来,因此这个状态的系统并没有进入真正意义上的休眠状态,还在持续耗电。

hibernate(suspend to disk)

这种休眠会将内存中的系统状态写入交换空间内,当系统启动时就可以从交换空间内读回系统状态。 这种情况下系统可以完全断电,但由于要保存/读取系统状态到/从交换空间,因此速度会比较慢,而且需要进行一些配置(下面会说到)

hybrid(suspend to both)

结合了上面两种休眠类型。它像hibernate一样将系统状态存入交换空间内,同时也像suspend一样并不关闭电源。 这种,在电源未耗尽之前,它能很快的从休眠状态恢复。而若休眠期间电源耗尽,则它可以从交换空间中恢复系统状态。

suspend 休眠

进入 suspend 特别简单,无需额外的配置,在 systemd 系统上直接执行 systemctl suspend 就行了。\

systemctl suspend

它的实际动作由 systemd-suspend.service 所定义, 在 archlinux 上,它长成这样子的:

#  SPDX-License-Identifier: LGPL-2.1+
#
#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.

[Unit]
Description=Suspend
Documentation=man:systemd-suspend.service(8)
DefaultDependencies=no
Requires=sleep.target
After=sleep.target

[Service]
Type=oneshot
ExecStart=/usr/lib/systemd/systemd-sleep suspend

Hibernation 休眠

由于 hibernation 休眠要求将内存中的内容写入到交换空间中,因此你至少要有一个空间大于内存的交换分区或者交换文件。 (其实若交换空间不够内存大也不是一定就无法进行hibernation休眠,可以尝试运行 echo 0 |sudo tee /sys/power/image_size, 这会让系统在写入交换空间时尽可能的进行压缩,但这种方法也无法保证一定能够休眠成功)

若之前没有创建交换分区,那么可以临时创建一个交换文件来用。比如下面命令创建一个5G的交换文件

sudo dd if=/dev/zero of=/swapfile bs=10240 count=524288
sudo mkswap /swapfile
sudo chmod 0600 /swapfile
sudo swapon /swapfile
sudo cp /etc/fstab /etc/fstab.bak
echo "/swapfile swap swap default 0 0" |tee -a /etc/fstab
Setting up swapspace version 1, size = 5 GiB (5368705024 bytes)
no label, UUID=d0f0c682-e1fa-416f-8fe2-b554b8ca363a
/swapfile swap swap default 0 0

除此创建交换分区之外,我们还需要修改kernel的启动参数,让系统在启动时先尝试从交换空间中恢复状态。 具体操作如下:

1. 如果使用交换分区来保存,则只需要为添加kernel的启动参数 resume=交换分区 即可

(1) 查看那块分区是交换分区

swapon

NAME      TYPE      SIZE USED PRIO
/dev/sda2 partition   8G 280K   -2
/swapfile file        5G   0B   -3

可以看出交换分区为 /dev/sda2

(2) 修改 /etc/default/grub, 为 GRUB_CMDLINE_LINUX_DEFAULT 行添加参数 resume=/dev/sda2

sudo sed -i '/GRUB_CMDLINE_LINUX_DEFAULT/ s!"$! resume=/dev/sda2"!' /etc/default/grub

2. 如果是使用交换文件,则需要添加两个参数 resume=交换文件所在磁盘 以及 resume_offset=交换文件在磁盘中的偏移位置:

(1) 查看交换文件所在磁盘

df /swapfile

文件系统          1K-块     已用     可用 已用% 挂载点
/dev/sda3      55253696 27582224 24834972   53% /

说明磁盘为 /dev/sda3

(2) 查看交换文件的偏移位置

sudo filefrag -v /swapfile|head -5
Filesystem type is: ef53
File size of /swapfile is 5368709120 (1310720 blocks of 4096 bytes)
 ext:     logical_offset:        physical_offset: length:   expected: flags:
   0:        0..   32767:    4653056..   4685823:  32768:            
   1:    32768..   65535:    4685824..   4718591:  32768:

这里可以看出物理偏移位置时4653056

(3) 修改 /etc/default/grub, 为 GRUB_CMDLINE_LINUX_DEFAULT 行添加参数 resume=/dev/sda3 resume_offset=4653056

sudo sed -i '/GRUB_CMDLINE_LINUX_DEFAULT/ s!"$! resume=/dev/sda3 resume_offset=4653056"!' /etc/default/grub

3. 重新生成 grub.cfg 文件

sudo grub-mkconfig -o /boot/grub/grub.cfg

(1) 配置initramfs添加 resume hook 修改 /etc/mkinitcpio.conf 文件,在 HOOKS 中添加 resume

sudo sed -i '/^HOOKS=/ s/)/ resume)/' /etc/mkinitcpio.conf

其中由两点需要注意:

  • 由于分区的label和UUID都是 udev 分配的,因此 resume 必须放在 udev 之后
  • 由于 systemd hook 已经有了 resume 的功能,因此若已经有了 systemd hook,则无需再添加 udev hook

(2) 重新生成initramfs

sudo mkinitcpio -g /boot/initramfs-linux-lily.img
==> Starting build: 4.16.12-2-lily
  -> Running build hook: [base]
  -> Running build hook: [udev]
  -> Running build hook: [autodetect]
  -> Running build hook: [modconf]
  -> Running build hook: [block]
  -> Running build hook: [filesystems]
  -> Running build hook: [keyboard]
  -> Running build hook: [fsck]
  -> Running build hook: [resume]
==> Generating module dependencies
==> Creating gzip-compressed initcpio image: /boot/initramfs-linux-lily.img
==> Image generation successful

(3) 重启,让配置生效

经过上面复杂的配置后,hibernation 休眠才能真正成功。与 suspend 休眠类似,我们也能使用 systemctl 来进行休眠

systemctl hibernate

类似的,它的实际动作由 systemd-hibernte.service 所定义, 在 archlinux 上,它长成这样子的:

#  SPDX-License-Identifier: LGPL-2.1+
#
#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.

[Unit]
Description=Hibernate
Documentation=man:systemd-suspend.service(8)
DefaultDependencies=no
Requires=sleep.target
After=sleep.target

[Service]
Type=oneshot
ExecStart=/usr/lib/systemd/systemd-sleep hibernate

hybrid 休眠

在配置好 hibernate 休眠后,也就能正常进行 hybrid 休眠了,方法是执行

systemctl hybrid-sleep

类似的,它的实际动作由 systemd-hybrid-sleep.service 所定义, 在 archlinux 上,它长成这样子的:

#  SPDX-License-Identifier: LGPL-2.1+
#
#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.

[Unit]
Description=Hybrid Suspend+Hibernate
Documentation=man:systemd-suspend.service(8)
DefaultDependencies=no
Requires=sleep.target
After=sleep.target

[Service]
Type=oneshot
ExecStart=/usr/lib/systemd/systemd-sleep hybrid-sleep

Sleep Hooks

从上面的service文件中可以看出,不管是哪种类型的系统休眠,其内部实际调用的都是 systemd-sleep.

man systemd-sleep
SYSTEMD-SUSPEND.SERVICE(8)  systemd-suspend.service SYSTEMD-SUSPEND.SERVICE(8)

NAME
       systemd-suspend.service, systemd-hibernate.service, systemd-hybrid-
       sleep.service, systemd-sleep - System sleep state logic

SYNOPSIS
       systemd-suspend.service

       systemd-hibernate.service

       systemd-hybrid-sleep.service

       /usr/lib/systemd/system-sleep

DESCRIPTION
       systemd-suspend.service is a system service that is pulled in by
       suspend.target and is responsible for the actual system suspend.
       Similarly, systemd-hibernate.service is pulled in by hibernate.target
       to execute the actual hibernation. Finally,
       systemd-hybrid-sleep.service is pulled in by hybrid-sleep.target to
       execute hybrid hibernation with system suspend.

       Immediately before entering system suspend and/or hibernation
       systemd-suspend.service (and the other mentioned units, respectively)
       will run all executables in /usr/lib/systemd/system-sleep/ and pass two
       arguments to them. The first argument will be "pre", the second either
       "suspend", "hibernate", or "hybrid-sleep" depending on the chosen
       action. Immediately after leaving system suspend and/or hibernation the
       same executables are run, but the first argument is now "post". All
       executables in this directory are executed in parallel, and execution
       of the action is not continued until all executables have finished.

       Note that scripts or binaries dropped in /usr/lib/systemd/system-sleep/
       are intended for local use only and should be considered hacks. If
       applications want to react to system suspend/hibernation and resume,
       they should rather use the Inhibitor interface[1].

       Note that systemd-suspend.service, systemd-hibernate.service, and
       systemd-hybrid-sleep.service should never be executed directly.
       Instead, trigger system sleep states with a command such as "systemctl
       suspend" or similar.

       Internally, this service will echo a string like "mem" into
       /sys/power/state, to trigger the actual system suspend. What exactly is
       written where can be configured in the "[Sleep]" section of
       /etc/systemd/sleep.conf or a sleep.conf.d file. See systemd-
       sleep.conf(5).

OPTIONS
       systemd-sleep understands the following commands:

       -h, --help
           Print a short help text and exit.

       --version
           Print a short version string and exit.

       suspend, hibernate, hybrid-sleep
           Suspend, hibernate, or put the system to hybrid sleep.

SEE ALSO
       systemd-sleep.conf(5), systemd(1), systemctl(1), systemd.special(7),
       systemd-halt.service(8)

NOTES
        1. Inhibitor interface

https://www.freedesktop.org/wiki/Software/systemd/inhibit

systemd 238                                         SYSTEMD-SUSPEND.SERVICE(8)

根据 systemd-sleep 的manual pages,可以看到在系统休眠之前以及从休眠状态恢复之后,都会并行地调用 /usr/lib/systemd/system-sleep 中的脚本,并传递两个参数。

第一个参数用来指定是开始休眠还是从休眠状态恢复,分别对应的字符串 “pre” 与 “post”.

第二个参数用来指明休眠的类型,分别为字符串 “suspend”, “hibernate” 以及 “hybrid-sleep”

定时执行休眠

systemd 系统中的定时任务是由timer来实现的,而每个timer都与一个service相对应。

一般情况下,timer的名称与service一致,但必要时可以通过在.timer文件中的 [Timer] 部分指定 Unit= 选项来控制一个与timer不同名的service。

下面是一个timer的例子,每天21:30分开始自动hibernate休眠

[Unit]
Description=Hibernate every 21:30:00

[Timer]
OnCalendar=*-*-* 21:30:00
Persistent=true
Unit=systemd-hibernate.service

[Install]
WantedBy=timers.target

定时唤醒休眠的linux

使用 rtcwake 可以在给定的时间唤醒处于休眠状态的电脑

其主要用法为:

sudo rtcwake -m ${mode} -t ${time_t}
# 或者
sudo rtcwake -m ${mode} -s ${seconds}

其中,参数mode为待机模式,有以下几个选项:

standby
普通待机模式,为默认选项,对应 ACPI state S1

mem
suspend休眠,对应 ACPI state S3

disk
hibernation 休眠,对应 ACPI state S4

off
通过调用系统的关机命令来休眠,对应 ACPI state S5
参数 time_t 为从 1970-01-01, 00:00 UTC 开始到现在的秒数,可以通过 date 命令来将时间字符串转换成这个秒数,比如

sudo rtcwake -m disk -t $(date -d 08:30 +%s)

就是进行 hibernation 休眠,并于08:30分唤醒

参数 seconds 为秒数,表示从现在开始的多少秒后,系统唤醒。



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