[Cerowrt-devel] the agile thread, post-sugarland thoughts, etc

[Sebastian Moeller]

Hi Dave,

sugarland really took stability under load to a new level. My typical UDP flooding experiments failed to take the router down even though I opened the flood gates for a full hour (against qos; will repeat against simple-qos once time permits); not even a single report in dmesg on the router. Nice work. Thanks for all the hard work. (If time allows I will try to run a few more stability tests and will report noteworthy results back, if any should show up)

best
	sebastian

On Sep 19, 2012, at 09:49 , Dave Taht wrote:

> I am enjoying the thread on agile over here: http://esr.ibiblio.org/?p=4564
> 
> Trying to formalize some stuff that I do instinctively into language
> more folk grok would be good.
> 
> One of the better links to come from it was this one:
> 
> http://blogs.valvesoftware.com/abrash/valve-how-i-got-here-what-its-like-and-what-im-doing-2/
> 
> This is something like what we've done with the bufferbloat effort -
> find something worthwhile, start a project to do it. However steam has
> a revenue model that we thus far lack. It does help to be making
> something lots of people want, and I suppose the hard problem is
> making people aware we have something they want.
> 
> Speaking of that, the 3.6-rc6 kernel I was working on which has most
> of the cerowrt stuff in it, but for x86 and ubuntu is here:
> http://snapon.lab.bufferbloat.net/~cero1/deb/
> 
> and (in trying to lick the memory problems) I've been doing some
> builds for the 32MB ram nanostation M5 and picostation 2HP, based on
> the current cerowrt patch sets. With a single SSID I haven't been able
> to crash the 2HP yet with a variety of traffic. It's easy to calculate
> however how to crash nearly any access point with extra SSIDs
> 
> if (Total spare ram - (4 wireless queues, 1000 packets = 2Mbytes
> roughly for each = 8Mbytes) * SSIDS) < 0)
>          boom()
> 
> This would be improvable with a multi hw queue fq_codel as each
> hardware queue could share an overall fq_codel queue (factor of 4
> decrease), however, it seems to make more sense to have the queueing
> in the mac layer below the SSID abstractions.
> 
> What's currently in cerowrt is eric dumazet's suggestions to reduce
> packet allocations under load. The above math was worse before - no
> matter the packet size, it seemed as though 2k and 4k allocations
> would be exausted.
> 
> ...
> 
> After I recover from the sprint required to get "sugarland" out the
> door, I'd like to work on ways to do scrum and sprint-like things
> (google hangouts?) to spread the knowledge and work around, and to
> parallelize the effort more.
> So much work remains. Truly addressing the wireless problem hasn't
> even started.
> 
> I have to admit that after doing something like 30 official releases
> of cerowrt out the last 18 months, I'd
> really like to hand over the reins to that to someone else. Worse is
> after the openwrt unfreeze, new kernels will start to appear, and
> while working with Linux 3.6 and later would be helpful, I'd rather
> have stability for a while to work on higher layers of the stack, and
> get analytical. Doing both "stable" maintainence and trying to move
> forward on new kernels is a problem...
> 
> Next up for me is working on qos-scripts, analytical models and tests,
> and updating my test deployment to
> this generation of code if all goes well. I just dumped a ton of raw
> data into the deBloat repo, too. Also have a few patches for the linux
> and openwrt mainlines to polish...
> 
> On other fronts, I'm still working the basic funding angles and trying
> to fix things with amazon. I was encouraged enough by your (thus far
> failed) attempts at financial help to sink the time I did into
> sugarland (sugar helped too, I think she needs a job title). If it
> wasn't for the outpouring of your support, I'd have given up. Thx. I
> sure hope sugarland is better than -10.
> 
> There has been an upswing in corporate interest in the last few weeks,
> I may have some news on that shortly.
> 
> I had planned originally to get to barcelona for the wireless summit
> and the linux conference. I may still make the second (issue is in
> doubt, though). Is anyone besides jg going to this?
> 
> http://www.wirelesssummit.org/
> 
> It's near the home of guifi.net which is one of the larger wireless
> networks I've ever heard of.
> 
> --
> Dave Täht
> http://www.bufferbloat.net/projects/cerowrt/wiki - "3.3.8-26 is out
> with fq_codel!"
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