[Advice needed] Do I really want QoS, or not?

Post new topic   Reply to topic    DD-WRT Forum Index -> Broadcom SoC based Hardware
Goto page 1, 2, 3  Next
Author Message
dragonC
DD-WRT User


Joined: 23 May 2015
Posts: 272

PostPosted: Mon Aug 02, 2021 15:18    Post subject: [Advice needed] Do I really want QoS, or not? Reply with quote
Hi all,

I am on a R7000 running 7/29/21's b47097. ISP spec is 200mbps down/up, although it could reach 280-300 mbps (without QoS). No overclocking.

I am currently setting a 280000kbit/s (same on downlink & uplink) QoS on WAN using HTB & FQ_CODEL_FAST. On top of that, I put a hard bandwidth cap to a few devices (IoT devices, old laptop/iPad for kids etc.)

My question is, does this really benefit me? Would I be better of leaving QoS off, and what do I lose if so? Alternatively, if I turn off QoS, do I gain anything flipping SFE/STP on at my current bandwidth?

Thanks in advance.
Sponsor
feliciano
DD-WRT Guru


Joined: 24 Oct 2008
Posts: 1079
Location: Latin America

PostPosted: Mon Aug 02, 2021 18:54    Post subject: QoS guidelines Reply with quote
If you think you're going to have bottlenecks with your bandwidth you can enable QoS for prioritizing some equipments and/or services above others. On the contrary, if you think your bandwidth is enough, enabling QoS tends to throtle back those services/equipments you're not marking as priority. Therefore if you're close to your ceiling, it makes sense to enable QoS. Otherwise, you will notice better performance leaving it off.

The above is the short answer, as the QoS is a complex and interesting subject.

_________________
If you want support, please read first the announcements and forum rules.
Si usted desea ayuda, por favor lea primero los anuncios y las reglas del foro.
dragonC
DD-WRT User


Joined: 23 May 2015
Posts: 272

PostPosted: Mon Aug 02, 2021 20:51    Post subject: Re: QoS guidelines Reply with quote
feliciano wrote:
If you think you're going to have bottlenecks with your bandwidth you can enable QoS for prioritizing some equipments and/or services above others. On the contrary, if you think your bandwidth is enough, enabling QoS tends to throtle back those services/equipments you're not marking as priority. Therefore if you're close to your ceiling, it makes sense to enable QoS. Otherwise, you will notice better performance leaving it off.

The above is the short answer, as the QoS is a complex and interesting subject.


So in other words, I should just leave QoS off unless I notice a bandwidth problem.

What about bufferbloat? I don't fully understand the specific network behaviors 'bufferbloat' refer to, but seems QoS is a way to keep that low. The only place I can measure it is on DSLReports speedtest -- bufferbloat is indeed lower (especially on upload) when QoS is on. Do people favor leaving QoS on because of this?
dragonC
DD-WRT User


Joined: 23 May 2015
Posts: 272

PostPosted: Wed Aug 04, 2021 16:14    Post subject: Reply with quote
Bump. Any other opinions/advice to consider?
ho1Aetoo
DD-WRT Guru


Joined: 19 Feb 2019
Posts: 2900
Location: Germany

PostPosted: Wed Aug 04, 2021 17:06    Post subject: Reply with quote
Well you can certainly google yourself

A high bufferbloat is bad, depending on how good or bad the line is you can observe a lag / bufferbloat of up to several seconds.

I claim that slows down the smooth network experience
Internet pages load very slowly
VoIP is no longer possible without interruptions

With a good QoS and heavy load you have only a slightly higher latency than under idle.
No matter if large amounts of data are uploaded or downloaded in parallel - you don't really notice any difference / everything is as fast and smooth as usual.

whether you really need QoS depends on the internet connection itself - there are some providers who use QoS in their infrastructure themselves and with such providers the bufferbloat is usually already quite low.
MysticGold04
DD-WRT User


Joined: 20 Apr 2018
Posts: 174
Location: Somewhere remote

PostPosted: Wed Aug 04, 2021 17:11    Post subject: Reply with quote
QoS allows you to control the bottleneck, not your ISP.

It allows you to ensure enough bandwidth is available for higher priority services like video streaming, voice over IP calls, or certain gaming devices.

For example, I have cable service, and my speed test tops out at 230mb down and 12mb up. I have my QoS set at 180mb down and 9.6mb up. This allows me to have my son gaming on Xbox, us streaming Netflix, and other general network traffic without lagging or having high latency spikes - outside of ISP issues.

Hope this helps.

_________________
ASUS RT-AC3100 AP Merlin 386.12_4
ASUS RT-AC68U Media Bridge/Merlin 386.12_4 (x2)
ASUS RT-AC68U AP r54604
ASUS RT-AC68U Gateway/AP r54604
Edgerouter-4, v2.0.9-hotfix7
dragonC
DD-WRT User


Joined: 23 May 2015
Posts: 272

PostPosted: Wed Aug 04, 2021 17:30    Post subject: Reply with quote
MysticGold04 wrote:
QoS allows you to control the bottleneck, not your ISP.
network traffic without ... high latency spikes.



Thanks MysticGold04. This part you said is a more significant factor for me. My bandwidth, despite _only_ at 200mbps down/up, is not bottlenecked yet in my house -- almost all of the time, high bandwidth video streaming happens when everyone is watching the same video; when my son needs to stream videos, he is bottlenecked by his device WIFI (I intentionally put him on 2GHz-N and reserve the 5GHz-AC for us adults).

On the other hand, despite having plenty buffer bandwidth most of the time, I can see latency spikes having noticeable impact on load time when multiple devices are loading something without topping off the total capacity.

Is QoS (or the SQM that comes with it) "THE" way to reduce latency spikes in these situations, in which case I should keep it enabled. Or is there other solutions outside of QoS?
feliciano
DD-WRT Guru


Joined: 24 Oct 2008
Posts: 1079
Location: Latin America

PostPosted: Wed Aug 04, 2021 23:37    Post subject: Reply with quote
Imagine this:
Your ISP offers you 200Mbps. Great.
You share that Internet indoors, several equipments over 2.4GHz, but you have walls and neighbors' interference, so when you check the one doing streaming, it shows it's connected at 36Mbps (and remember what I've just said: the air is shared among several). Therefore you are having a local bottleneck. The QoS between the router and the Internet wouldn't be THE solution in that case (although it could help a little, deppending of the specific numbers and services).

On the other hand, 5GHz or 6GHz have more bandwith, but less coverage.

Bottomline: YMMV, there's no universal solution. One has to pin point what's is going on for a given situation and start from there.

_________________
If you want support, please read first the announcements and forum rules.
Si usted desea ayuda, por favor lea primero los anuncios y las reglas del foro.
flyzipper
DD-WRT Guru


Joined: 21 Feb 2016
Posts: 504

PostPosted: Thu Aug 05, 2021 0:17    Post subject: Reply with quote
Lots of good advice already, I'll add some other things to think about and you can decide if they'd apply/benefit you...

- adding hard caps - I'm not a fan of this because it often unnecessarily restricts the performance of those devices even if there's nothing else going on that would benefit from that restriction. If you can dial in the appropriate priorities for your network, I'd suggest trusting QoS to handle those priorities. Then every device is free to burst the bandwidth they need, on a relative basis.
- keep the rules simple - on my network, I bump the priority of the Xbox (MAC priority), and that's it. For me, this ensures anything else that consumes bandwidth, or increases latency, is at a lower priority. This also makes it much easier to wrap your head around what's going on with prioritized traffic. If I had kids doing something heavy, I might consider dropping their priority, but the majority of traffic is in the general bucket.
- the R7000 is slow with QoS - in my testing of my R7000, I find it's able to apply simple QoS rules and get good bufferbloat performance with 200mbps, which sounds like it's fine for your current use. Something to keep in mind if you increase your subscribed bandwidth (you may need to replace the R7000 if you want traffic shaping for much greater speeds). This weak HW would also probably benefit from the "keep it simple" advice above -- simple rules are generally less taxing (but I'll admit I haven't tested this to confirm).
sideup66
DD-WRT User


Joined: 26 Nov 2016
Posts: 102

PostPosted: Fri Aug 06, 2021 3:45    Post subject: Reply with quote
the short answer: do you need QOS? maybe.

the longer answer:
As stated by others it depends. As your configuration sits, do you get wan speed without qos? how bad is the bufferbloat? is it maxing out the meter or just a little bit? Without QOS are your speeds ok? Even if you have a little bufferbloat, do you notice any performance issues while online? Im personally in the school of KISS, keep it simple stupid. If your specs are ok, and you are not experiencing a big issue, run without QOS (more rules = more complication = more stuff that can break).

What I would suggest in your case is to turn off QOS (reboot router after, although off I like to just give everything a clean slate. Then measure your speed with something like DSLreports. If no major bufferbloat or obvious issue, live with it for a while, look for any issues you encounter. If you do, then set QOS accordingly. If not, leave it off.
Alozaros
DD-WRT Guru


Joined: 16 Nov 2015
Posts: 6389
Location: UK, London, just across the river..

PostPosted: Fri Aug 06, 2021 9:55    Post subject: Reply with quote
generally DDWRT has a good default speed balance...
i've never had a need of QoS...and consider its a CPU taxing service, to sacrifice your performance, you must be very in demand of it......

_________________
Atheros
TP-Link WR740Nv1 ---DD-WRT 55179 WAP
TP-Link WR1043NDv2 -DD-WRT 55303 Gateway/DoT,Forced DNS,AP Isolation,Ad-Block,Firewall
TP-Link WR1043NDv2 -DD-WRT 55303 Gateway/DoT,Forced DNS,Ad-Block,Firewall,x4VLAN,VPN
TP-Link WR1043NDv2 -Gargoyle OS 1.15.x AP,DNS,QoS,Quotas
Qualcomm-Atheros
Netgear R7800 --DD-WRT 55416 Gateway/DoT,AD-Block,Forced DNS,AP&Net Isolation,x3VLAN,Firewall,Vanilla
Netgear R9000 --DD-WRT 55363 Gateway/DoT,AD-Block,AP Isolation,Firewall,Forced DNS,x2VLAN,Vanilla
Broadcom
Netgear R7000 --DD-WRT 55416 Gateway/SmartDNS/DoH,AD-Block,Firewall,Forced DNS,x3VLAN,VPN
NOT USING 5Ghz ANYWHERE
------------------------------------------------------
Stubby DNS over TLS I DNSCrypt v2 by mac913
mac913
DD-WRT Guru


Joined: 02 May 2008
Posts: 1847
Location: Canada

PostPosted: Fri Aug 06, 2021 15:02    Post subject: Reply with quote
Alozaros wrote:
generally DDWRT has a good default speed balance...
i've never had a need of QoS...and consider its a CPU taxing service, to sacrifice your performance, you must be very in demand of it......


I totally agree with Aloraros. I don't use QoS plus the other 2 Off-Site routers I work with don't use QoS; I have no complaints.

_________________
Home Network on Telus 1Gb PureFibre - 10GbE Copper Backbone
2x R7800 - Gateway & WiFi & 3xWireGuard - DDWRT r53562 Std k4.9

Off Site 1

R7000 - Gateway & WiFi & WireGuard - DDWRT r54517 Std
E3000 - Station Bridge - DDWRT r49626 Mega K4.4

Off Site 2

R7000 - Gateway & WiFi - DDWRT r52330 Std
E2000 - Wired ISP IPTV PVR Blocker - DDWRT r35531


YAMon 3.4.6 | DNSCrypt-Proxy V2
ho1Aetoo
DD-WRT Guru


Joined: 19 Feb 2019
Posts: 2900
Location: Germany

PostPosted: Fri Aug 06, 2021 15:20    Post subject: Reply with quote
Well - bufferbloat is no imagination.
You can measure it and if you have an internet connection that has a bloat of up to several seconds under high load, then it is clearly noticeable.

Just start a download + upload to fully utilize the connection and then be amazed how slow e.g. simple surfing is.

If other links are embedded in the pages and content is loaded from external servers, the bufferbloat quickly accumulates.
And then the Internet page no longer loads in 2 seconds but needs 30 seconds.

With QoS I notice no difference, I do not care if the line is fully loaded.

https://ibb.co/PcRPjY2
dragonC
DD-WRT User


Joined: 23 May 2015
Posts: 272

PostPosted: Fri Aug 06, 2021 23:12    Post subject: Reply with quote
Thank you all very much. These are very practical and pragmatic perspectives. I hadn't previously considered the R7000 hardware & bufferbloat being 'noticeable' in real world usage (it's definitely visible in DSLReports test).

After reading these I do now notice one of the router's CPU is close to maxed by a kernel process when QoS is in full swing (i.e. during the speed test).

I should take some time and do similar tests (like what 'ho1Aetoo' pasted in) on command line too. Best case is the bufferbloat shown on DSLReports does not affect real world usage, in which case I'd leave that off like you all suggested.
ho1Aetoo
DD-WRT Guru


Joined: 19 Feb 2019
Posts: 2900
Location: Germany

PostPosted: Sat Aug 07, 2021 10:06    Post subject: Reply with quote
dragonC wrote:
The only place I can measure it is on DSLReports speedtest -- bufferbloat is indeed lower (especially on upload) when QoS is on.



btw https://fast.com/ also shows the bufferbloat (loaded latency)
Under the settings just change the parameters (test duration etc)
then you can see it better



fast2.jpg
 Description:
 Filesize:  36.92 KB
 Viewed:  3873 Time(s)

fast2.jpg



fast.jpg
 Description:
 Filesize:  23.57 KB
 Viewed:  3880 Time(s)

fast.jpg


Goto page 1, 2, 3  Next Display posts from previous:    Page 1 of 3
Post new topic   Reply to topic    DD-WRT Forum Index -> Broadcom SoC based Hardware All times are GMT

Navigation

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You can attach files in this forum
You can download files in this forum