Dec 23, 2021 21:00:00

What is the verification result of the effective speed of the 2.5Gb Ethernet adapter for Linux?

Software engineer Jeff Gering, who

has tested a variety of PCI Express- enabled network cards (NICs) since the announcement of the Raspberry Pi Compute Module 4 , an embedded Raspberry Pi in 2020, said 2.5 for Linux. We are verifying the effective speed of the Gb Ethernet adapter.

Check your driver! Faster Linux 2.5G Networking with Realtek RTL8125B | Jeff Geerling
https://www.jeffgeerling.com/blog/2021/check-your-driver-faster-linux-25g-networking-realtek-rtl8125b

One of the NICs that Mr. Göring has been interested in, who has verified various NICs, is the 'cheap 2.5 gigabyte (Gb) Ethernet adapter'. The 2.5 Gigabit Ethernet adapter is said to be able to achieve the highest bandwidth for a NIC that can be used with one PCI Express 2.0 lane of Raspberry Pi. 'The 2.5Gbit Ethernet Adapter is much more accessible than a 10Gigabit network, and is the best option for users who already have a CAT5e LAN cable wired and who find it cumbersome to replace it with a CAT6 or later LAN cable. '.

As an example of a NAS using such a 2.5 Gigabit Ethernet adapter , Mr. Gering cites ASUSTOR's Drivestor 4 Pro and Radxa Taco based on Raspberry Pi, and measures their effective speed. Both NAS have in common that they use Realtek's 2.5 Gigabit Ethernet adapter ' RTL8125B'.

To measure the effective speed, the tool iperf3 for measuring the network bandwidth between the client and the server and the effective speed is used, and the effective speed of the two NAS is 1.89 Gbps (1.89 Gb / s) for 'Radxa Taco'. ), 'Drivestor 4 Pro' was 1.87Gbps, which was slightly lower than 1.9Gbps. In addition, when using RAID, the effective speed of 'Radxa Taco' has dropped to 1.51 Gbps.

In addition, Mr. Göring said, 'I thought that the driver of the Linux kernel could improve it, but there was no difference,' he said, saying that updating the kernel did not show a significant improvement in effective speed.

Subsequently, Göring downloaded the 2.5Gigabit Ethernet driver for Linux from Realtek's website and updated the driver to the latest version, 9.007.01. After that, the result of running the benchmark test again is as follows, and it is clear that the effective speed is clearly improved.

From these experiences, Mr. Göring said, 'If you do not get the expected performance, please try updating the driver etc. to check the effective speed.' 'Since few Linux users are using 2.5 gigabit NICs, This kind of performance issue is rarely discussed. '