[Bloat] fremont flent node: what's the network setup there?

[Bloat] fremont flent node: what's the network setup there?

[Aaron Wood]

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I'm comparing some numbers between the fremont node and a friend's Droplet
running netserver.

We've previous noted that we don't see more than a 120Mbps download rate
from the fremont node.

Today I was able to confirm in multiple back-to-back runs that the fremont
node was only giving me about 120Mbps of throughput, while both dslreports
and the droplet were giving me ~180Mbps (and 500ms of latency in the cable
head-end).

However, I noticed when running without SQM on my router here at home that
download latency from the fremont node was virtually non-existent, vs. the
very large latency that I was seeing from both the droplet and dsl-reports.

Box-plots:
https://drive.google.com/file/d/0B1xfqN4OiFEPODI4cEZjZ1NGeGVtc3RKbGJQR3ltaHhyb1Bz/view

That very, very low send latency from the fremont node makes me think that
it might be running BBR as the default congestion control algorithm?  If I
run the cubic-reno test without any SQM, the results look pretty awful, but
without specifying the TCP cc alg, it seems to behave very, very well
(albeit not as much throughput as I think I should get).

Re-enabling cake (at 170Mbps downstream, 12Mbps up), I can't seem to get
much more than that 120Mbps from the router (even though I've tested it at
900Mbps as the netserver host itself).  Am I running into a cpu limitation
in the NAT/forwarding modules?

-Aaron

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Re: [Bloat] fremont flent node: what's the network setup there?

[Dave Taht]

the simplest answer is for you to send me an ssh key I can put there.
second simplest is for me to fire up a new box and new kernel over
there and put your ssh key there also. It would not surprise me for
linode to have a rate limit somewhere elsewhere....

 Lemme go spin up a new box in a minute.

It's currently sch_fq and cubic on kernel 4.8.6-x86_64-linode78.

also:

net.ipv4.tcp_ecn = 1
net.ipv4.tcp_ecn_fallback = 1


On Wed, Oct 4, 2017 at 10:41 PM, Aaron Wood <woody77@gmail.com> wrote:
> I'm comparing some numbers between the fremont node and a friend's Droplet
> running netserver.
>
> We've previous noted that we don't see more than a 120Mbps download rate
> from the fremont node.
>
> Today I was able to confirm in multiple back-to-back runs that the fremont
> node was only giving me about 120Mbps of throughput, while both dslreports
> and the droplet were giving me ~180Mbps (and 500ms of latency in the cable
> head-end).
>
> However, I noticed when running without SQM on my router here at home that
> download latency from the fremont node was virtually non-existent, vs. the
> very large latency that I was seeing from both the droplet and dsl-reports.
>
> Box-plots:
> https://drive.google.com/file/d/0B1xfqN4OiFEPODI4cEZjZ1NGeGVtc3RKbGJQR3ltaHhyb1Bz/view
>
> That very, very low send latency from the fremont node makes me think that
> it might be running BBR as the default congestion control algorithm?  If I
> run the cubic-reno test without any SQM, the results look pretty awful, but
> without specifying the TCP cc alg, it seems to behave very, very well
> (albeit not as much throughput as I think I should get).
>
> Re-enabling cake (at 170Mbps downstream, 12Mbps up), I can't seem to get
> much more than that 120Mbps from the router (even though I've tested it at
> 900Mbps as the netserver host itself).  Am I running into a cpu limitation
> in the NAT/forwarding modules?
>
> -Aaron
>
> _______________________________________________
> Bloat mailing list
> Bloat@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/bloat
>



-- 

Dave Täht
CEO, TekLibre, LLC
http://www.teklibre.com
Tel: 1-669-226-2619