SQM QoS - DL Speeds Axed When Enabled

[LJFox]

Hi all,

I've been trying to setup SQM to see if I can improve package flow on my network. Is a 30MB dl cable connection and I'm using an Archer C7 v4 with OpenWRT 19.07.4.

Here's a test result with SQM off, 40s DL and UL lenght: http://www.dslreports.com/speedtest/67178021

With SQM enabled, using cake and piece_of_cake, my connection falls to this: http://www.dslreports.com/speedtest/67178216

So BufferBloat goes from C to A but my DL speed crashes from ~310mb/s to ~175mb/s. Upload speeds remain stable.

When I change the scripts to simple or simplest (fq_code), DL speeds goes up somewhat, to ~230mb/s: http://www.dslreports.com/speedtest/67178820

Download ingress is set to 286740kbits/s.
Upload egress is set to 28800kbits/s.

Here's the result of a "top d -1" while dslreport and speedtest were running:

And here's a tc -s qdisc right after a test:

root@OpenWrt:~# tc -s qdisc
qdisc noqueue 0: dev lo root refcnt 2
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
qdisc fq_codel 0: dev eth0 root refcnt 2 limit 10240p flows 1024 quantum 1514 ta rget 5.0ms interval 100.0ms memory_limit 4Mb ecn
Sent 12541355566 bytes 10814719 pkt (dropped 0, overlimits 0 requeues 66)
backlog 0b 0p requeues 66
maxpacket 1514 drop_overlimit 0 new_flow_count 77 ecn_mark 0
new_flows_len 0 old_flows_len 0
qdisc noqueue 0: dev br-lan root refcnt 2
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
qdisc noqueue 0: dev eth0.1 root refcnt 2
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
qdisc tbf 1: dev eth0.2 root refcnt 2 rate 28800Kbit burst 3596b lat 300.0ms
Sent 131417785 bytes 271681 pkt (dropped 1688, overlimits 152694 requeues 0)
backlog 0b 0p requeues 0
qdisc fq_codel 110: dev eth0.2 parent 1: limit 1001p flows 1024 quantum 1518 tar get 5.0ms interval 100.0ms memory_limit 4Mb ecn
Sent 131417785 bytes 271681 pkt (dropped 1688, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
maxpacket 2744 drop_overlimit 0 new_flow_count 52440 ecn_mark 0
new_flows_len 1 old_flows_len 4
qdisc ingress ffff: dev eth0.2 parent ffff:fff1 ----------------
Sent 1162226807 bytes 841234 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
qdisc noqueue 0: dev wlan1 root refcnt 2
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
qdisc noqueue 0: dev wlan0 root refcnt 2
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
qdisc tbf 1: dev ifb4eth0.2 root refcnt 2 rate 286740Kbit burst 35806b lat 300.0 ms
Sent 1192511231 bytes 841234 pkt (dropped 0, overlimits 176851 requeues 0)
backlog 0b 0p requeues 0
qdisc fq_codel 110: dev ifb4eth0.2 parent 1: limit 1001p flows 1024 quantum 1514 target 5.0ms interval 100.0ms memory_limit 4Mb ecn
Sent 1192511231 bytes 841234 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
maxpacket 1536 drop_overlimit 0 new_flow_count 84340 ecn_mark 0
new_flows_len 1 old_flows_len 17

Any idea? I tried searching through the forum and on r/openwrt but couldn't find anything that could relate to my issue. As far as I can see, my router's CPU is not throttling and my connection is not fast enough to be bottlenecked.

Any and all help is appreciated.

[dlakelan]

@LJFox

my router's CPU is not throttling and my connection is not fast enough to be bottlenecked.

It absolutely is throttling, you are showing 8% idle averaged over 1 second, which means there were undoubtedly periods of time when it can't meet the required processing, and this is at ~ 175Mbps so it's never going to get to ~ 300Mbps

You could try enabling SQM only on upload, or you could try getting a substantially faster router.

[LJFox]

Interesting. I was reading that completely wrong.

Thanks for the reply! I've marked this solved so it can be closed.

[johntheman]

Heya,

Piggybacking on this, how would you enable SQM only for upload?

I'm considering getting a new router just because of this.

[dlakelan]

Put 0 for the download speed

[moeller0]

Not to put too fine a point on it, but I had my 100/40 link operating at 50/40 since my router did not allow robust and reliable shaping at higher speeds, but for my use case 50 with SQM was better behaved than 100 without SQM. So by all means try it out, but maybe keep somthing like SQM at 150/28 as an option to try if disabling the download shaper does not work out?

[LJFox]

That's exactly what I plan to do. 27MB/s should be enough for our daily use and I can just disable SQM if I plan to make a large download (as in from Steam or alike).

The C7 serves our needs fine, I don't think an upgrade is justified.

[dlakelan]

@LJFox

The C7 serves our needs fine, I don't think an upgrade is justified.

If you decide to upgrade you can use the C7 as an access point