Internet connection speed is half when using the router with openwrt

Installing and Using OpenWrt
1

I have installed openwrt on my D-Link Covr-X1860. I have set the wan connection to PPPoE, because the ISP router is set to act as a modem. This was the configuration also with the original firmware. Now if I measure the speed with speedtest or waveform, the download speed is about half the speed of the connection as compared to the original firmware (120Mbps vs 240Mbps), upload speed is the same. Since I have multiple units, only one is flashed with openwrt, thus I still have the original setup. Changing the device to the original one (with the original firmware) the speed is doubled (and equals the ISP provided speed), changing to the openwrt unit the speed is halved. What can be the problem, what should I check? My laptop is connected vie the same cable. The only change is the firmware.

2

Try

  • enable packet_steering
  • enable software flow offload
1 Like
3

Thanks! It solves.

Packet steering was enabled (default), but not "enable (all CPUs)" (whatever it means). Changing it solves the problem.

Enabling software flow offload also solves.

Now which one should I leave in the new state to have the least side effects? Or just keep both changed?

4

So packet_steering (or rather receive packet steering, RPS) configures which CPUs will participate in processing packets from the NICs. The default, IIRC, is something clever, where the CPU processing the actual NIC interrupt is not used for RPS, but all other CPUs are. This is desirable if you have a) high throughput network traffic and b) enough CPUs to make this worthwhile. However routers tend to have few CPUs (1-4, but let's ignore the 1 CPU case as there is nothing to steer to except the sole CPU) and for 2 CPUs the default basically just separates NIC interrupt and soft interrupt network processing (which includes qdiscs and hence stuff like SQM) on separate CPUs, and that tends not to be great for performance... (I have no data from 4 CPU routers, well possible that the default already is better there compared to (all CPUs)).

As the GUI says this is not fully compatible with SQM, but that should be fixable eventually. If you do not use SQM this is a great way to improve throughput.

Your network, your rules. As long as stuff works as you expect/desire you are fine, no?

1 Like
5

Thanks, this makes the things a bit more clear and gives a direction for further info.

6

This topic was automatically closed 10 days after the last reply. New replies are no longer allowed.