[Cerowrt-devel] [Bloat] Comcast upped service levels -> WNDR3800 can't cope...

Sebastian Moeller moeller0 at gmx.de
Fri Aug 29 13:25:14 EDT 2014

Hi Aaron,

On Aug 29, 2014, at 18:57 , Aaron Wood <woody77 at gmail.com> wrote:

> Comcast has upped the download rates in my area, from 50Mbps to 100Mbps.  This morning I tried to find the limit of the WNDR3800.  And I found it.  50Mbps is still well within capabilities, 100Mbps isn't.
> And as I've seen Dave say previously, it's right around 80Mbps total (download + upload).
> http://burntchrome.blogspot.com/2014/08/new-comcast-speeds-new-cerowrt-sqm.html
> I tried disabling downstream shaping to see what the result was, and it wasn't pretty.

	You could try to set the interface to 100Mbps with ethtool and exercise cerowrt BQL implementation a bit ;)

>  I also tried using the "simplest.qos" script, and that didn't really gain me anything, so I went back to the simple.qos script (those results aren't included above).
> It looks like it's definitely time for a new router platform (for me).
> Or, we need to find a way to implement the system such that it doesn't max out a 680MHz mips core just to push 100Mbps of data.  That's roughly 10K cpu cycles per packet, which seems like an awful lot.  Unless the other problem is that the memory bus just can't keep up.  My experience of a lot of these processors is that the low-level offload engines have great DMA capabilities for "wire-speed" operation, but that the processor core itself can't move data to save it's life.

	Could you try simplest.qos and replace HTB with TBF? We still do not know whether there is a cheaper option than HTB that still works okay-ish (I only have 16D 2U, so can not easily test myself). I guess that TBF is just as expensive as HTB since both shaw more or less the same token bucket algorithm...

> What's the limit of the EdgeRouter Lite?

	I think this tops out at ~ 80-90Mbps combined, but there is no BQL yet. Given the price of tho unit it would be really nice if that would work for the 150-200Mbps combined that seem to be needed in the near future.

> Or should I start looking for something like this:
> http://www.gateworks.com/product/item/ventana-gw5310-network-processor
> (although that's an expensive board, given the very low production volume, for the same cost I could probably build a small passively-cooled mini/micro-atx setup running x86 and dual NICs).
> -Aaron
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