Re: Realtek NIC uses over 1 Watt with no traffic

[Heiner Kallweit]

On 20.11.2018 15:45, Andrew Lunn wrote:
> On Tue, Nov 20, 2018 at 09:40:25AM +0100, Paul Menzel wrote:
>> Dear Linux folks,
>>
>>
>> Using Ubuntu 18.10, Linux 4.18.0-11-generic, PowerTOP 2.9 shows, the NIC
>> uses 1.77 Watts. A network cable is plugged in, but there is no real traffic
>> according to `iftop`. Only an email program is running.
>>
>>     $ lspci -nn -s 3:00.1
>>     03:00.1 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd.
>> RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller [10ec:8168] (rev
>> 12)
>>
>> Is that a measurement error, or does the NIC really need that much power?
> 
> Hi Paul
> 
> This sounds like Energy Efficient Ethernet, EEE, is not enabled.
> 
> What does ethtool --show-eee ethX say?
> 
>      Andrew
> 
The r8169 driver doesn't support the get_eee ethtool_ops callback.
For certain chip versions EEE gets enabled in the PHY init, for others
not and some don't seem to support EEE at all.

Apart from EEE one important factor affecting power consumption is ASPM.
This was recently enabled for certain chip versions.

Information that would help:

whether Wake-on-LAN is enabled ("Wake-on:" line from ethtool output)

lspci -vv output for the Realtek NIC

Info from powertop about package C states. With ASPM my system reaches
50% PC7 + 50% PC10.

dmesg output filtered for "r8169". Primarily relevant is the line with
the chip name and XID.

Heiner