Re: [Bloat] DSLReports Speed Test has latency measurement built-in

[jb <justin@dslr.net>]

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This is how I've changed the graph of latency under load per input from you
guys.

Taken away log axis.

Put in two bands. Yellow starts at double the idle latency, and goes to 4x
the idle latency
red starts there, and goes to the top. No red shows if no bars reach into
it.
And no yellow band shows if no bars get into that zone.

Is it more descriptive?

(sorry to the list moderator, gmail keeps sending under the wrong email and
I get a moderator message)

On Thu, Apr 23, 2015 at 8:05 PM, jb <justinbeech@gmail.com> wrote:

> This is how I've changed the graph of latency under load per input from
> you guys.
>
> Taken away log axis.
>
> Put in two bands. Yellow starts at double the idle latency, and goes to 4x
> the idle latency
> red starts there, and goes to the top. No red shows if no bars reach into
> it.
> And no yellow band shows if no bars get into that zone.
>
> Is it more descriptive?
>
>
> On Thu, Apr 23, 2015 at 4:48 PM, Eric Dumazet <eric.dumazet@gmail.com>
> wrote:
>
>> Wait, this is a 15 years old experiment using Reno and a single test
>> bed, using ns simulator.
>>
>> Naive TCP pacing implementations were tried, and probably failed.
>>
>> Pacing individual packet is quite bad, this is the first lesson one
>> learns when implementing TCP pacing, especially if you try to drive a
>> 40Gbps NIC.
>>
>> https://lwn.net/Articles/564978/
>>
>> Also note we use usec based rtt samples, and nanosec high resolution
>> timers in fq. I suspect the ns simulator experiment had sync issues
>> because of using low resolution timers or simulation artifact, without
>> any jitter source.
>>
>> Billions of flows are now 'paced', but keep in mind most packets are not
>> paced. We do not pace in slow start, and we do not pace when tcp is ACK
>> clocked.
>>
>> Only when someones sets SO_MAX_PACING_RATE below the TCP rate, we can
>> eventually have all packets being paced, using TSO 'clusters' for TCP.
>>
>>
>>
>> On Thu, 2015-04-23 at 07:27 +0200, MUSCARIELLO Luca IMT/OLN wrote:
>> > one reference with pdf publicly available. On the website there are
>> > various papers
>> > on this topic. Others might me more relevant but I did not check all of
>> > them.
>>
>> > Understanding the Performance of TCP Pacing,
>> > Amit Aggarwal, Stefan Savage, and Tom Anderson,
>> > IEEE INFOCOM 2000 Tel-Aviv, Israel, March 2000, pages 1157-1165.
>> >
>> > http://www.cs.ucsd.edu/~savage/papers/Infocom2000pacing.pdf
>>
>>
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>
>

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