[Cerowrt-devel] smoketest BQL-40 is out

Dave Taht dave.taht at gmail.com
Thu Feb 23 07:39:30 EST 2012

A couple quick notes:

1) I had hoped that the kernel development phase was over, and all I'd
have to do is track the 3.3 rcs from linus and keep up with openwrt's

It is looking like a few more mods to iptables and tc are going to be
required over the next month or two to get things right.

2) That said, most of what remains is scripting and 'glue', and it
will generally be possible to install a package under test on an
existing box without having to reflash the whole thing and
reconfigure. For example, you can pull the new aqm-script package from
either the git repository or the current 3.3 build - an example of the
latter would be:

cd /tmp
opkg remove aqm-scripts
wget http://huchra.bufferbloat.net/~cero1/3.3/3.3-rc4-1/packages/aqm-scripts_1.2.1-6_all.ipk
opkg install ./aqm-scrip*

right now anyway! (see item 1)

It would improve our cycle time to schedule and focus on each
scripting problem, perhaps in irc, for things like the ADSL problem.

Regrettably I'm not in a position to do any real work on that this week.

On Thu, Feb 23, 2012 at 10:49 AM, Dave Taht <dave.taht at gmail.com> wrote:
> I'm aware there are several messages in
> the backlog I need to respond to, but I am travelling
> at the moment and eyeball deep in meetings. (presently in NJ,
> next week philly, and then I get back to the bloatlab in isc
> in california friday-ish.
> As best as I recall there was no real difference between
> the AQM script and the QoS script in bql-40, and I may
> not get around to doing a 'bql-42' per se' but go right
> into the 3.3 development process.
> This will not be the final url for the 3.3 development
> series, but
> http://huchra.bufferbloat.net/~cero1/3.3/
> has that.
> I made a small dent in the qos/aqm problem there,
> (my intent was to basically treat the above as 'bql-41' -
>  I wanted to treat 3.3 issues and bql issues separately,
>  but lack time to do both, and 3.3 is going swimmingly, so...)
> but I'm puzzled as to what you are seeing below.
> 0) Did you enable the aqm script? If you merely run it
> without enabling it, nothing happens. Similarly, the qos script
> needs to be disabled.
> 1) Neither the AQM nor qos script does ADSL overhead right,
> and I'd got puzzled on what was 'right' after fiddling with it.
> 2) both qos and aqm calculated the sfq 'limit' variable wrong, and
> neither did ipv6 work right at all.
> I believe, but don't remember, that at least those fixes got made in
> the 3.3rc4-1 code. Actually there's a better fix for the ipv6 issue
> than what's there...
> 3) I am not intending to stick with the aqm script as structured now,
> but to finish modifying the 'debloat' script to have all the features required.
> that one has a bunch of semi-working queue models in it.
> If yer gonna hack scripts, please take a look at that one.
> There are plenty of things it needs and the qos and aqm scripts
> are more feature complete, tho...
> 4) re updates: I have to warn against doing sysupgrade "and keep files
> in place", as the based filesystem does change, and I'm not making
> huge attempts at dealing with that. so doing a backup
> then a sysupdate -n (-n meaning don't preserve files over the backup)
> is generally a good idea.
> anyway:
> commit be09b8c15b6dc6bf4cb7da3112c598138a9c77ef
> Author: Dave Taht <dave.taht at bufferbloat.net>
> Date:   Tue Feb 14 14:38:40 2012 +0000
>    SFQ is limited in packets. RED is in bytes. tcrules.awk conflated these
>    The original openwrt shaper took the RED byte calculation...
>    and reused it to specify a limit for sfq. However, sfq uses
>    packets rather than bytes, so it was specifying, say 16000 bytes
>    and translating that to 16000 packets.
>    This was not an error I prior to 3.3, because SFQ had a
>    hard coded limit of 127 packets. It is now.
>    So this commit puts a lower and upper bound on the maximum packets
>    that is sane, but is not pre 3.2 compatible.
> commit 44f8febbd34686564516c3261a911bd7cffcf714
> On Thu, Feb 23, 2012 at 6:21 AM, Sebastian Moeller <moeller0 at gmx.de> wrote:
>> Hi Dave,
>> I finally got around to update from rc6 to bql-40, to try the ATM shaping. The update was a breeze, great work!
>>        I am sad to report that for my ATM link AQM does not work for me as well as QoS does. My measurement consists out of using ping to get the RTT to the first ISP hop (as taken from trace route) while concurrently saturating the up link with a dropbox upload (which I usually give that a headstart of 10 seconds to go into bandwidth ceiling): AQM gives the same bad avg RTT of 1.2 seconds as no shaping at all does, while QoS gives me an avg RTT of around 24ms (best case RTT is around 13ms on my link, so the link stays pretty useable).
>>        I tried to apply the same changes to /usr/lib/aqm/generate.sh and /usr/lib/qos/generate.sh to make the them better understand the peculiarities of my ATM adsl1 connection, but it seems I did something wrong for the AQM script since my change does not have any effect there… (both modified files attached). I usually only  shape up- and down-stream to 97% of the line rate, which works ok with QoS. (And all my tests have been done, very unscientifically, using my mac laptop over the 5GHz wireless band of the router… )
>>        While this is not too helpful, it might give some hints for bql-42, as from the roadmap I take it you will tackle the dsl issue there. I am just about to move and switch from DSL to cable internet, so unfortunately this might be my last test…
>> (BTW, I have been playing with the -s option of ping to change the payload size and for my measly 3008kbps down, 512kbps up connection I can actually see the 48 byte ATM package boundaries in avg RTTs (-c 100), for each new ATM package I roughly get 1ms added to the RTT (as expected when doing the math the my line rate). So I think it should be possible to figure out whether a link uses ATM as carrier or not (IIRC newer ADSL systems like AT&T's verse HSI use ADSL2 over PTM-TC instead of ATM so touch connections still have per package overhead to account for but lack the weird ATM repack issues).
>>        I also have a hunch that using this method it should be possible to deduct a link's overhead (as taken understood by tc's step option) from a properly prepared ping sweep. In other words my hypothesis is that it should be possible to run a script on a non-shaped idle link and figure out the optimal parameters for stab. But I digress… (And alas, in two days my DSL connection will be gone and I can not even test my hypothesis in any meaningful way until then...))
>> best
>>        Sebastian
>> On Feb 14, 2012, at 11:53 AM, Dave Taht wrote:
>>> http://huchra.bufferbloat.net/~cero1/bql-smoketests/bql-40/
>>> changes in this release:
>>> kernel 3.3-rc3
>>> bind 9.9rc2
>>> ntpd + dnssec removed (too buggy)
>>> snmpd installed by default
>>> fprobe installed by default
>>> avahi installed by default
>>> sort of better working 'aqm' shaper installed
>>> ** when configured uses hfsc + sfqred
>>> ** still has trouble with ipv6, diffserv, and tcp elephants
>>> ** no adsl overhead support
>>> I will be travelling later this week. What I'm mostly
>>> working on right now is better ipv6 support.
>>> --
>>> Dave Täht
>>> SKYPE: davetaht
>>> US Tel: 1-239-829-5608
>>> FR Tel: 0638645374
>>> http://www.bufferbloat.net
>>> _______________________________________________
>>> Cerowrt-devel mailing list
>>> Cerowrt-devel at lists.bufferbloat.net
>>> https://lists.bufferbloat.net/listinfo/cerowrt-devel
> --
> Dave Täht
> SKYPE: davetaht
> US Tel: 1-239-829-5608
> http://www.bufferbloat.net

Dave Täht
SKYPE: davetaht
US Tel: 1-239-829-5608

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