Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
---
title: "Hibernate When Network Idle"
date: 2020-04-14T20:57:40+10:00
draft: true
tags:
- linux
---
i have a pc at home which is often on, but not so often used. i'd like it to hibernate most of the time, unless i want to use it or it is doing something itself. it's possible, stringing together a few things:
### if the network's idle
Install [vnstat](https://wiki.archlinux.org/index.php/VnStat)
```
pacman -Syu vnstat
```
this allows us to query network usage split up by 5 minute intervals:
```
~ › vnstat -i wlp2s0 -5 4
wlp2s0 / 5 minute
time rx | tx | total | avg. rate
------------------------+-------------+-------------+---------------
2020-04-15
00:10 2.47 MiB | 835.14 KiB | 3.28 MiB | 91.85 kbit/s
00:15 913.94 KiB | 398.04 KiB | 1.28 MiB | 35.83 kbit/s
00:20 410.53 KiB | 301.39 KiB | 711.92 KiB | 19.44 kbit/s
00:25 657.27 KiB | 750.08 KiB | 1.37 MiB | 38.43 kbit/s
------------------------+-------------+-------------+---------------
```
using this we'll query the usage over the last 5 minutes using `jq`
```
~ › vnstat -i wlp2s0 -5 1 --json 1 | jq ".interfaces[0].traffic.fiveminute[0]"
```
```json
{
"id": 169,
"date": {
"year": 2020,
"month": 4,
"day": 15
},
"time": {
"hour": 0,
"minute": 25
},
"rx": 673042,
"tx": 768082
}
```
### sleep for a while
by default this simply suspends, which is quick to start again, but isn't the lowest power consumption mode.
```sh
rtcwake --date "+30min"
```
it gave me `rtcwake: write error` unless i explicitly specified `-m mem`
```sh
sudo rtcwake -m mem --date "+5min"
```
```sh
or rtcwake -m no -l -t $(date +%s -d 'tomorrow 10:00')?
```
https://jlk.fjfi.cvut.cz/arch/manpages/man/rtcwake.8.en
### cron job
we want to control when the napping will occur, and sleep for different times throughout the day. something like
* 3am ~ 6am: sleep time
* 6am ~ 10am: wake during morning
* 10am ~ 4pm: afternoon nap
* 4pm ~ 3am: wake during evening
```
~~~~
```
### roll it into a script we can run periodically
```sh
#!/bin/zsh
# Usage: ./nap-if-idle.sh "+30min"
# arg 1
# duration of nap
NAP_TIME="+30min"
# arg 2
# how deep is the sleep
SLEEP_MODE="mem"
RX=$(vnstat -i wlp2s0 -5 1 --json 1 | jq ".interfaces[0].traffic.fiveminute[0].rx")
TX=$(vnstat -i wlp2s0 -5 1 --json 1 | jq ".interfaces[0].traffic.fiveminute[0].tx")
TOTAL_KB=(( $RX + $TX_))
IDLE_KB=(( 1 * 1024 )) # 1 MiB
if [[ $TOTAL -gt $IDLE_KB ]]; then
echo 'System seems to be idle, having a nap' | systemd-cat
rtcwake --date $NAP_TIME
fi
```
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment