Re: [Cerowrt-devel] archer c7 v2, policing, hostapd, test openwrt build

[Sebastian Moeller <moeller0@gmx.de>]

Hi Jonathan,


On Mar 24, 2015, at 04:16 , Jonathan Morton <chromatix99@gmail.com> wrote:

> 
>> On 24 Mar, 2015, at 02:00, Sebastian Moeller <moeller0@gmx.de> wrote:
>> 
>> So I got around to a bit of rrul testing of the dual egress idea to asses the cost of IFB, but the results are complicated (so most likely I screwed up).
> 
> IFB is normally used on the download direction (as a substitute for a lack of AQM at the ISP), so that’s the one which matters.  Can you try a unidirectional test which exercises only the download direction?  

	I will try to get around to this later this week, not sure whether I manage though.

> This should get the clearest signal - without CPU-load interference from the upload direction.

	I agree, but if IFB redirection truly is costly enough to bother with fixing/avoiding it should also cause a noticeable effect on the full ingress-egress stress test, I would assume. But at least for my limited tests it did not… Or to put it differently, if avoiding the IFB does not increase bandwidth use under full load it is not going to help with getting a router’s combined shaping performance improve, or do I see something wrong. Now maybe it is a critical building block for better performance that is masked at full load by something else, that is why I tried the reduced bandwidth loads (35000 bidirectional) but even there the effect was rather mild… That said, I will retry with download shaping only (vie se00 egress) and simplest.qos (instead of simple.qos) to move the heavy filtering out of the way. I wonder whether anybody has a good idea of how to measure the router’s cpu usage during a rrul test (maybe the main effect of avoiding IFB is not to increase bandwidth usage, but to free up cpu cycles for performing other task, which still would be quite valuable, I guess)

Best Regards
	Sebastian

> 
> - Jonathan Morton
>