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

[jb]

That makes sense. Ok.

On Wed, Apr 22, 2015 at 12:14 PM, Simon Barber <simon at superduper.net> wrote:

>   If you set the window only a little bit larger than the actual BDP of
> the link then there will only be a little bit of data to fill buffer, so
> given large buffers it will take many connections to overflow the buffer.
>
> Simon
>
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>
> On April 21, 2015 4:18:10 PM jb <justin at dslr.net> wrote:
>
>> Regarding the low TCP RWIN max setting, and smoothness.
>>
>> One remark up-thread still bothers me. It was pointed out (and it makes
>> sense to me) that if you set a low TCP max rwin it is per stream, but if
>> you do multiple streams you are still going to rush the soho buffer.
>>
>> However my observation with a low server rwin max was that the smooth
>> upload graph was the same whether I did 1 upload stream or 6 upload
>> streams, or apparently any number.
>> I would have thought that with 6 streams, the PC is going to try to flood
>> 6x as much data as 1 stream, and this would put you back to square one.
>> However this was not what happened. It was puzzling that no matter what,
>> one setting server side got rid of the chop.
>> Anyone got any plausible explanations for this ?
>>
>> if not, I'll run some more tests with 1, 6 and 12, to a low rwin server,
>> and post the graphs to the list. I might also have to start to graph the
>> interface traffic on a sub-second level, rather than the browser traffic,
>> to make sure the browser isn't lying about the stalls and chop.
>>
>> This 7800N has setting for priority of traffic, and utilisation (as a
>> percentage). Utilisation % didn't help, but priority helped. Making web low
>> priority and SSH high priority smoothed things out a lot without changing
>> the speed. Perhaps "low" priority means it isn't so eager to fill its
>> buffers..
>>
>> thanks
>>
>>
>> On Wed, Apr 22, 2015 at 8:13 AM, jb <justin at dslr.net> wrote:
>>
>>> Today I've switched it back to large receive window max.
>>>
>>> The customer base is everything from GPRS to gigabit. But I know from
>>> experience that if a test doesn't flatten someones gigabit connection they
>>> will immediately assume "oh congested servers, insufficient capacity" and
>>> the early adopters of fiber to the home and faster cable products are the
>>> most visible in tech forums and so on.
>>>
>>> It would be interesting to set one or a few servers with a small receive
>>> window, take them from the pool, and allow an option to select those,
>>> otherwise they would not participate in any default run. Then as you point
>>> out, the test can suggest trying those as an option for results with
>>> chaotic upload speeds and probable bloat. The person would notice the
>>> beauty of the more intimate connection between their kernel and a server,
>>> and work harder to eliminate the problematic equipment. Or. They'd stop
>>> telling me the test was bugged.
>>>
>>> thanks
>>>
>>>
>>> On Wed, Apr 22, 2015 at 12:28 AM, David Lang <david at lang.hm> wrote:
>>>
>>>> On Tue, 21 Apr 2015, David Lang wrote:
>>>>
>>>>  On Tue, 21 Apr 2015, David Lang wrote:
>>>>>
>>>>>  I suspect you guys are going to say the server should be left with a
>>>>>>> large
>>>>>>> max receive window.. and let people complain to find out what their
>>>>>>> issue
>>>>>>> is.
>>>>>>>
>>>>>>
>>>>>> what is your customer base? how important is it to provide faster
>>>>>> service to teh fiber users? Are they transferring ISO images so the
>>>>>> difference is significant to them? or are they downloading web pages where
>>>>>> it's the difference between a half second and a quarter second? remember
>>>>>> that you are seeing this on the upload side.
>>>>>>
>>>>>> in the long run, fixing the problem at the client side is the best
>>>>>> thing to do, but in the meantime, you sometimes have to work around broken
>>>>>> customer stuff.
>>>>>>
>>>>>
>>>>> for the speedtest servers, it should be set large, the purpose is to
>>>>> test the quality of the customer stuff, so you don't want to do anything on
>>>>> your end that papers over the problem, only to have the customer think
>>>>> things are good and experience problems when connecting to another server
>>>>> that doesn't implement work-arounds.
>>>>>
>>>>
>>>> Just after hitting send it occured to me that it may be the right thing
>>>> to have the server that's being hit by the test play with these settings.
>>>> If the user works well at lower settings, but has problems at higher
>>>> settings, the point where they start having problems may be useful to know.
>>>>
>>>> David Lang
>>>> _______________________________________________
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>>>> Bloat at lists.bufferbloat.net
>>>> https://lists.bufferbloat.net/listinfo/bloat
>>>>
>>>>
>>>
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