[Cerowrt-devel] Comcast Uplink Buffers

[Dave Taht]

kill offloads.

On Thu, Mar 5, 2015 at 11:05 AM, Aaron Wood <woody77 at gmail.com> wrote:
> Bill,
>
> I'd recommend setting the bandwidth values low (very low) at first, just to
> establish that the setup is working correctly.  I'm able to get better
> control of latency at those bitrates on an WNDR3800:
>
> http://burntchrome.blogspot.com/2014/05/fixing-bufferbloat-on-comcasts-blast.html
>
> I'd start slow, and then start raising the limits until you see issues.
>
> But it's possible something else is causing issues.  Is your netperf source
> wired to the Atom?  (for bandwidth levels that ruler flat, I normally assume
> wired.  I've seen wifi give odd 30ms jumps in latency, but those normally
> come with an drop in bandwidth as well).
>
> What else is running on the Atom box?
>
> -Aaron
>
>
>
>
> On Thu, Mar 5, 2015 at 7:49 AM, William Katsak <wkatsak at gmail.com> wrote:
>>
>> Dave,
>>
>> Thanks for the reply. I should have made it clearer that I am not running
>> this on a Netgear 3800, I am running the sqm system on an Atom D510 box at
>> 1.66 GHz (two cores + hyperthreads) with 2 GB RAM and good Intel NICs. While
>> running the rrul, the CPU is barely breaking a sweat.
>>
>> The OS is Ubuntu server and I've made a nice wrapper to run simple.qos via
>> the if-pre-up/post-down hooks.
>>
>> Can you suggest any tweaks to the settings that would better take
>> advantage of the extra CPU that I have?
>>
>> Thanks,
>> Bill
>>
>>
>>
>>
>> On 03/05/2015 10:43 AM, Dave Taht wrote:
>>>
>>> well, cerowrt's inbound shaper runs out of cpu at +60mbits. That is
>>> possibly part of your problem.
>>>
>>> the peaks you are seeing are not bad - but to me, probably indicative
>>> of running out of cpu, which will among other things, drop packets
>>> burstily.
>>>
>>> As comcast has rolled out 100mbit+ service in a ton of places
>>> (including my home), we really, really, really need to find a way to
>>> do better rate shaping at higher speeds (or develop a faster policer)
>>> on some successor hardware.
>>>
>>> If you turn off inbound shaping (0 for that parameter) my measurements
>>> typically show over 600ms of latency on inbound on comcast at 100mbit
>>> down, but at least, doing the tcp_upload tests, we can hold the upload
>>> more under control. It is a totally unsatisfactory thing to have
>>> downloads got so much out of control, it really messes up other
>>> things, inside of a few seconds, on big downloads, but at this point I
>>> have to recommend turning off inbound shaping and just living with it.
>>>
>>> Very high on my list now is finally writing (or tom sawyering someone
>>> into writing!) "bobbie - the kinder, gentler policer" in the hope that
>>> that could actually run faster and better than shaping does on this
>>> low end hardware.
>>>
>>>
>>>
>>> On Thu, Mar 5, 2015 at 7:35 AM, William Katsak <wkatsak at gmail.com> wrote:
>>>>
>>>> Hello all,
>>>>
>>>> I just moved and had to switch my ISP from Optimum (Cablevision) to
>>>> Comcast
>>>> (100/10 link).
>>>>
>>>> I am running my own port of simple.qos over to Debian/Ubuntu, and it
>>>> worked
>>>> fine on Cablevision (I basically use scripts in if-pre-up.d and
>>>> if-post-down.d to set the variables set up/tear down simple.qos).
>>>>
>>>> However, since I moved over to Comcast, I am seeing something like 600
>>>> ms of
>>>> uplink buffering according to Netlyzer. Also, the Internet browsing
>>>> "feels"
>>>> slow when Netflix is in use elsewhere in the apartment (like before I
>>>> knew
>>>> anything about bufferbloat).
>>>>
>>>> My config looks like this:
>>>> UPLINK=7500
>>>> DOWNLINK=85000
>>>> QDISC=fq_codel
>>>> LLAM="tc_stab"
>>>> LINKLAYER="none"
>>>> OVERHEAD=0
>>>> STAB_MTU=2047
>>>> STAB_MPU=0
>>>> STAB_TSIZE=512
>>>> AUTOFLOW=0
>>>> LIMIT=1001   # sane global default for *LIMIT for fq_codel on a small
>>>> memory
>>>> device
>>>> ILIMIT=
>>>> ELIMIT=
>>>> ITARGET="auto"
>>>> ETARGET="auto"
>>>> IECN="ECN"
>>>> EECN="NOECN"
>>>> SQUASH_DSCP="1"
>>>> SQUASH_INGRESS="0"
>>>> IQDISC_OPTS=""
>>>> EQDISC_OPTS=""
>>>> TC=`which tc`
>>>> #TC="sqm_logger tc"# this redirects all tc calls into the log
>>>> IP=$( which ip )
>>>> INSMOD=`which modprobe`
>>>> TARGET="5ms"
>>>> IPT_MASK="0xff"
>>>> IPT_MASK_STRING="/${IPT_MASK}"     # for set-mark
>>>>
>>>> I've also attached the output of a run of rrul against
>>>> netperf.bufferbloat.net.
>>>>
>>>> Any insight?
>>>>
>>>> Thanks,
>>>> Bill
>>>>
>>>>
>>>> --
>>>> ****************************************
>>>> William Katsak <wkatsak at gmail.com>
>>>> ****************************************
>>>>
>>>> _______________________________________________
>>>> Cerowrt-devel mailing list
>>>> Cerowrt-devel at lists.bufferbloat.net
>>>> https://lists.bufferbloat.net/listinfo/cerowrt-devel
>>>>
>>>
>>>
>>>
>>
>> --
>> ****************************************
>> William Katsak <wkatsak at gmail.com>
>> ****************************************
>> _______________________________________________
>> Cerowrt-devel mailing list
>> Cerowrt-devel at lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/cerowrt-devel
>
>



-- 
Dave Täht
Let's make wifi fast, less jittery and reliable again!

https://plus.google.com/u/0/107942175615993706558/posts/TVX3o84jjmb