[Bloat] Steam In Home Streaming on ath9k wifi

[Caleb Cushing]

ping from laptop

C:\Users\xeno>ping 192.168.1.105 -n 100

Pinging 192.168.1.105 with 32 bytes of data:
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=5ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128
Reply from 192.168.1.105: bytes=32 time=4ms TTL=128
Reply from 192.168.1.105: bytes=32 time=3ms TTL=128

Ping statistics for 192.168.1.105:
    Packets: Sent = 100, Received = 100, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 3ms, Maximum = 5ms, Average = 3ms


On Fri, Nov 24, 2017 at 3:35 AM Neil Davies <neil.davies at pnsol.com> wrote:

> On 24 Nov 2017, at 09:20, Hal Murray <hmurray at megapathdsl.net> wrote:
>
>
> neil.davies at pnsol.com said:
>
> There are a few more issues - the relative drift between the two clocks
> can be as high as 200ppm, though typically 50-75ppm is what we observe, but
> this drift is monotonic.
>
>
> 200 ppm seems pretty high, but not off scale.  If ntpd is running and not
> getting confused by long queuing delays, it should correct the drift to
> well
> under 1 ppm.  If you turn on loopstats, you can graph it.
>
>
> I’m saying that is the maximum rate of drift between two clocks even
> when they are under NTP control. As you say below the clock rates
> are not completely stable they are temperature dependent.
> When we did this with the guys at CERN we could
> correlate the results with the workload (see below for references).
>
> We’ve got ~1M experiments using this approach across various networks,
> the numbers are what we are seeing in practice.
>
> The caveat is that, after a while (i.e several 100s) the clock drift can
> make
> a significant difference (i.e a few ms) in the one-way delay estimation.
>
>
> If you are blasting the network and adding long queuing delays, ntpd can
> easily get confused.
>
> There is another quirk to keep in mind.  The temperature coefficient of
> the
> crystal is ballpark of 1 ppm per C.  Things can change significantly if an
> idle system starts flinging lots of bits around.
>
>
> Also NTP can make changes at one (or both) ends - they show up as distinct
> direction changes in the drift.
>
>
> I'm not sure what you mean by "direction change".  I'd expect a graph of
> the
> time offset vs time to be linear and the slope would have a sharp change
> if
> ntpd changed it's "drift" correction and/or maybe a rounded bend as a
> system
> warmed up.
>
>
> Don’t forget you are measuring the difference in the rates between two NTP
> clocks,
> hence the change when one of the NTP systems decides to change the drift
> rate
> the relative rate can change direction.
>
>
> ----------
>
> Are you happy with whatever you are doing?   Should we try to set things
> up
>
> so ntpd works well enough?  How close would you like the times to be?  …
>
>
> Yep, we’re very happy - we don’t care that there is a linear clock drift
> (we
> can correct for that) and the step changes are infrequent and can be
> eliminated
> from the long term analysis.
>
> You might find §4.4 (esp §4.4.5) and §5.6 in
> https://cds.cern.ch/record/1504817/files/CERN-THESIS-2013-004.pdf
> interesting.  It illustrates these sort of issues.
>
>
>
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
>
> _______________________________________________
> Bloat mailing list
> Bloat at lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/bloat
>
-- 
Caleb Cushing

http://xenoterracide.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.bufferbloat.net/pipermail/bloat/attachments/20171126/0e946bab/attachment-0002.html>