rd0 ip routing prioritisation appears to result in slow external network downloads

[nathanpiper]

Rancher Desktop Version

main 4c29159

Rancher Desktop K8s Version

1.21.7

What operating system are you using?

macOS

Operating System / Build Version

12.0.1

What CPU architecture are you using?

x64

Windows User Only

No response

Actual Behavior

Experiencing really slow external network downloads on the VM. I first notice when image pulls appeared to be taking an extremely long time to complete.

Steps to Reproduce

1. Shell into VM instance and download a test file using wget:

wget --output-document=/dev/null https://ftp.zetta.net.au/pub/testfiles/testfile.300Mb

Experience slow performance

2. Delete prioritised ip route:
   ip route del default via 192.168.205.1 dev rd0 metric 201

Experience expected (faster) performance

Result

wget --output-document=/dev/null https://ftp.zetta.net.au/pub/testfiles/testfile.300 Mb Connecting to ftp.zetta.net.au (119.252.91.137:443) saving to '/dev/null' null 0% | | 992k 0:53:10 ETA

Expected Behavior

wget --output-document=/dev/null https://ftp.zetta.net.au/pub/testfiles/testfile.300 Mb Connecting to ftp.zetta.net.au (119.252.91.137:443) saving to '/dev/null' null 3% |*** | 10.1M 0:01:54 ETA^

Additional Information

Appears to be introduced by the rd0 prioritisation scripting on this PR: #974

[nathanpiper]

I would love to help out here, but I'm a bit out of my depth on the networking configuration.

[mattfarina]

@jandubois can you please take a look at this.

[jandubois]

@jandubois can you please take a look at this.

Yes, already on my list to repro today.

If I can confirm, I will try to implement "point-to-point" mode for vde_vmnet. It eliminates the vde_switch, but means only a single VM will be able to connect to the vde_vmnet daemon (which is fine for Rancher Desktop because we only run a single VM so far). I don't know if this would fix things though, so just something to try.

[jandubois]

I've reproduced the issue, and have filed 2 PRs that will improve the situation somewhat:

virtualsquare/vde-2#35
lima-vm/vde_vmnet#31

The first one includes timings from my tests; the fixes improved download times of a 4GB ISO from 75min to 90s, which sounds awesome until you notice that it only takes 13s over slirp (and 3s directly on the host).