<div dir="ltr">It's too big because it's oversized so it's in the size domain. It's basically Little's law's value for the number of items in a queue.<br><br><blockquote style="margin:0 0 0 40px;border:none;padding:0px"><b><i>Number of items in the system = (the rate items enter and leave the system) x (the average amount of time items spend in the system)</i></b></blockquote><br>Which gets driven to the standing queue size when the arrival rate exceeds the service rate - so the driving factor isn't the service and arrival rates, but <b>the queue size </b>when <i><b>any service rate is less than an arrival rate.</b></i><div><br>In other words, one can find and measure bloat regardless of the enter/leave rates (as long as the leave rate is too slow) and the value of memory units found will always be the same.<br><br>Things like prioritizations to jump the line are somewhat of hacks at reducing the service time for a specialized class of packets but nobody really knows which packets should jump. Also, nobody can define what working conditions are so that's another problem with this class of tests.<br><br>Better maybe just to shrink the queue and eliminate all unneeded queueing delays. Also, measure the performance per "user conditions" which is going to be different for almost every environment (and is correlated to time and space.) So any engineering solution is fundamentally suboptimal. Even pacing the source doesn't necessarily do the right thing because that's like waiting in the waitlist while at home vs the restaurant lobby. Few care about where messages wait (unless the pitch is AQM is the only solution that drives to a self-fulfilling prophecy - that's why the tests have to come up with artificial conditions that can't be simply defined.)<br><br>Bob</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Oct 10, 2022 at 3:57 PM David Lang <<a href="mailto:david@lang.hm" target="_blank">david@lang.hm</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On Mon, 10 Oct 2022, Bob McMahon via Bloat wrote:<br>
<br>
> I think conflating bufferbloat with latency misses the subtle point in that<br>
> bufferbloat is a measurement in memory units more than a measurement in<br>
> time units. The first design flaw is a queue that is too big. This youtube<br>
> video analogy doesn't help one understand this important point.<br>
<br>
but the queue is only too big because of the time it takes to empty the queue, <br>
which puts us back into the time domain.<br>
<br>
David Lang<br>
<br>
> Another subtle point is that the video assumes AQM as the only solution and<br>
> ignores others, i.e. pacing at the source(s) and/or faster service rates. A<br>
> restaurant that let's one call ahead to put their name on the waitlist<br>
> doesn't change the wait time. Just because a transport layer slowed down<br>
> and hasn't congested a downstream queue doesn't mean the e2e latency<br>
> performance will meet the gaming needs as an example. The delay is still<br>
> there it's just not manifesting itself in a shared queue that may or may<br>
> not negatively impact others using that shared queue.<br>
><br>
> Bob<br>
><br>
><br>
><br>
> On Mon, Oct 10, 2022 at 2:40 AM Sebastian Moeller via Make-wifi-fast <<br>
> <a href="mailto:make-wifi-fast@lists.bufferbloat.net" target="_blank">make-wifi-fast@lists.bufferbloat.net</a>> wrote:<br>
><br>
>> Hi Erik,<br>
>><br>
>><br>
>>> On Oct 10, 2022, at 11:32, Taraldsen Erik <<a href="mailto:erik.taraldsen@telenor.no" target="_blank">erik.taraldsen@telenor.no</a>><br>
>> wrote:<br>
>>><br>
>>> On 10/10/2022, 11:09, "Sebastian Moeller" <<a href="mailto:moeller0@gmx.de" target="_blank">moeller0@gmx.de</a>> wrote:<br>
>>><br>
>>> Nice!<br>
>>><br>
>>>> On Oct 10, 2022, at 07:52, Taraldsen Erik via Cake <<br>
>> <a href="mailto:cake@lists.bufferbloat.net" target="_blank">cake@lists.bufferbloat.net</a>> wrote:<br>
>>>><br>
>>>> It took about 3 hours from the video was release before we got the<br>
>> first request to have SQM on the CPE's we manage as a ISP. Finally<br>
>> getting some customer response on the issue.<br>
>>><br>
>>> [SM] Will you be able to bump these requests to higher-ups and at<br>
>> least change some perception of customer demand for tighter latency<br>
>> performance?<br>
>>><br>
>>> That would be the hope.<br>
>><br>
>> [SM} Excellent, hope this plays out as we wish for.<br>
>><br>
>><br>
>>> We actually have fq_codel implemented on the two latest generations of<br>
>> DSL routers. Use sync rate as input to set the rate. Works quite well.<br>
>><br>
>> [SM] Cool, if I might ask what fraction of the sync are you<br>
>> setting the traffic shaper for and are you doing fine grained overhead<br>
>> accounting (or simply fold that into a grand "de-rating"-factor)?<br>
>><br>
>><br>
>>> There is also a bit of traction around <a href="http://speedtest.net" rel="noreferrer" target="_blank">speedtest.net</a>'s inclusion of<br>
>> latency under load internally.<br>
>><br>
>> [SM] Yes, although IIUC they are reporting the interquartile mean<br>
>> for the two loaded latency estimates, which is pretty conservative and only<br>
>> really "triggers" for massive consistently elevated latency; so I expect<br>
>> this to be great for detecting really bad cases, but I fear it is too<br>
>> conservative and will make a number of problematic links look OK. But hey,<br>
>> even that is leaps and bounds better than the old only idle latency report.<br>
>><br>
>><br>
>>> My hope is that some publication in Norway will pick up on that score<br>
>> and do a test and get some mainstream publicity with the results.<br>
>><br>
>> [SM] Inside the EU the challenge is to get national regulators and<br>
>> the BEREC to start bothering about latency-under-load at all, "some<br>
>> mainstream publicity" would probably help here as well.<br>
>><br>
>> Regards<br>
>> Sebastian<br>
>><br>
>><br>
>>><br>
>>> -Erik<br>
>>><br>
>>><br>
>>><br>
>><br>
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><br>
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