I put a number of my Linux systems into "standby" overnight. I have noticed that in standby, the Ethernet interfaces remain at full speed.
Now, we all know that higher-speed Ethernet sucks more power. From my own cursory testing of one of my boxes, this amounts to a 1-2W difference at both ends, total 3-4W, when comparing 10Mbps and 2.5Gbps. It's possible this is something particular to my setup, though - corroborating evidence would be helpful!
As all I need when my systems are in standby is the ability to respond to WOL packets, I wrote a small hook for systemd-sleep to throttle connection speed just before entering the sleep state, and restore auto-negotiation on wake up.
Once added,
I hope this helps others.
Now, we all know that higher-speed Ethernet sucks more power. From my own cursory testing of one of my boxes, this amounts to a 1-2W difference at both ends, total 3-4W, when comparing 10Mbps and 2.5Gbps. It's possible this is something particular to my setup, though - corroborating evidence would be helpful!
As all I need when my systems are in standby is the ability to respond to WOL packets, I wrote a small hook for systemd-sleep to throttle connection speed just before entering the sleep state, and restore auto-negotiation on wake up.
Bash:
$ cat /usr/lib/systemd/system-sleep/wol-ethspeed
#!/bin/bash
shopt -s nullglob
case $1 in
pre)
for i in /sys/class/net/e{n,th}*; do
/usr/sbin/ethtool -s `basename $i` autoneg off
/usr/sbin/ethtool -s `basename $i` speed 10
done
;;
post)
for i in /sys/class/net/e{n,th}*; do
/usr/sbin/ethtool -s `basename $i` autoneg on
done
;;
esacsystemctl suspend does the trick.I hope this helps others.
