Re: Low capped TCP network speeds over the Internet

[z411 <z411%omaera.org@localhost>]

On 3/6/26 02:48, Michael van Elst wrote:
> You may want to try this patch. It restricts each wm interface to a single
> send queue. A real fix would restrict each flow to a single queue, so
> that packets are not reordered. The patch also bumps the send queue
> to 4k packets, maybe not ideal, but that needs further analysis.

Thank you very much. If I understand correctly, this seems to have to do
with having multiple CPUs, but my VM is running on a single vCPU. I
still tried the patch to no effect. However, this will be useful if I
decide to increase the amount of vCPUs. Thanks.

In any case, I tried different buffer sizes, and the stability of the
connection seems to change with it. For example, with a 6303600 byte
buffer it can reach surprising speeds in the best case:

https://u.omaera.org/nbsd_good_6303600.png

That said, increasing the buffer this much makes the packet loss more
common and whenever it happens it seems to have a really hard time
recovering from it, to the point it often stalls completely. It's as if
it's choking:

https://u.omaera.org/nbsd_bad_5042880.png

So I feel comfortable setting it to a more conservative value like
3025728, which gives me comparable speeds to the other OSes I tried
while not compromising on stability so much:

https://u.omaera.org/nbsd_ok_3025728.png

I feel it's still slightly sensitive to any packet loss in comparison
but at least it can recover from it instead of stalling completely.

I also tried vioif(4) once again and it still crawls at KB/s speeds, so
I'll definitely stay with wm(4) - it's more than enough for a web server
(I don't have big files in it anyway), and as a VPN it also works as UDP
still works great with wm(4).

I hope this is useful for anyone else having trouble with NetBSD network
speeds under QEMU - make sure you try with E1000 emulation first. Since
UDP looked fine with virtio I wrongly assumed that was not the issue and
took forever to finally give E1000 a try.

I am not sure how much of this is expected or known behavior, but I feel
comfortable installing NetBSD now on my Japanese server. Hopefully I'll
learn more about it so I can provide better feedback when reporting
these issues. Feel free to contact me anytime if you'd like me to do
more testing.

Thank you for your time and insight.
- z411