[Cerowrt-devel] squash/ignore DSCP and mangle table questions

[Sebastian Moeller]

Hi leetminiwheat,

On Apr 15, 2015, at 03:35 , leetminiwheat <LeetMiniWheat at gmail.com> wrote:

> On Mon, Apr 13, 2015 at 5:39 PM, Sebastian Moeller <moeller0 at gmx.de> wrote:
>>        This looks reasonable.
>> 
>>> [...]
>> 
>>        I had a look at my cerowrt router and I also see txqueuelen at 1000, but IIRC that does not matter much anymore, since the wndr37/800 support BQL:
>> cat /sys/class/net/ge00/queues/tx-0/byte_queue_limits/limit_max
>> 3000
>> So even with txqueuelen = 1000 the tx queue will only hold 3000 bytes. For fib and friends it does not really matter as far as I can tell.
> 
> Interesting, I had been reading about BQL but didn't fully understand
> it until now. This clears up a lot of confusion, thank you.
> 
> I assume tweaking ring parameters from default RX:128 and TX:32
> doesn't matter anymore thenr?

	As far as I know we leave that alone, see: http://www.bufferbloat.net/projects/bloat/wiki/Linux_Tips:
“Set the size of the ring buffer for the network interface

NOTE: THIS HACK IS NO LONGER NEEDED on many ethernet drivers in Linux 3.3, which has Byte Queue Limits instead, which does a far better job."


> 
>> [...]
>> If you have time and netperf-wrapper it would be good to convince yourself and us again, that txqueuelen really does not matter for BQL’d interfaces by running RRUL tests with and without your modifications….
> 
> Will do if I can get a friend to set up a netperf server in a node at
> his datacenter he works at, though I believe he's using Debian Jessy
> without any kind of QoS, but his datacenter routers might screw with
> the packets. Maybe I can hook a spare box up to the WAN port
> temporarily to test with.

	Ah, there are three netperf servers out there that, as far as I know, we are allowed to use:
netperf-west.bufferbloat.net
netperf-east.bufferbloat.net
netperf-eu.bufferbloat.net

	My guess is the last one should be closest to you, and should do at least for initial tests. Having a faster closer netperf server available certainly is even more attractive.


Best Regards
	Sebastian