[Cerowrt-devel] performance numbers from WRT1200AC (Re: Latest build test - new sqm-scripts seem to work; "cake overhead 40" didn't)

Mikael Abrahamsson swmike at swm.pp.se
Thu Jun 25 05:12:08 EDT 2015

On Wed, 24 Jun 2015, Dave Taht wrote:

> From what I see here you are rarely, if ever, engaging fq_codel
> properly. Latencies are pretty high. In particular, I would suspect
> you are hitting offloads hard, and the current (fixed in linux 4.1)
> codel drop algorithm stops dropping below "maxpacket", which was meant
> in the ns2 code to be a MTU, but in the linux code ended up being a
> TSO sized (64k!) packet.
> tc -s qdisc show # will show the maxpacket.


I discovered also that I wasn't running ECN, I had set tcp_ecn = 2 on the 
linux box. All the tests done in 
http://swm.pp.se/aqm/flent-mikabr-150625-1.tar are now done with ECN 
working, without iperf3 running, and with and without SQM, but with 
default offload setting.

Also, now iperf3 says "0 packet lost" when I use that.

> 2) Please run your flent tests with -x --disable-log


> Use -t "title" to differentiate between variables under test.


> 3) I also tend to use flent's --remote-metadata=root at your_openwrtbox
> to get the stats on that box into the metadata. You have to add your
> local .ssh/id_rsa.pub key to
> your_openwrtbox:/etc/dropbear/authorized_keys file to do this.


> 4) With all that in hand, sticking up a tarball of the results makes
> for easy plotting of various other graphs, and using the flent-gui,
> you can combine results from each run easily, also.

See above.

> 5) try disabling offloads on all interfaces on the router (or running cake)

This is my next thing to test, I have some other things I need to try 

> My usual suite of tests is rrul, rrul_be, tcp_1up, tcp_1down, and tcp_2up_delay.


> and rtt_fair (if you have more than one target server available)...
> all without the iperf stuff....

I do not have another machine readily available here at home.

> 6) I am pretty interested as to what happens *without* sqm at the max 
> forwarding rate with fq_codel engaged on all these tests.

This is included. Why did you want to do this test? Just to see if the 
WRT1200AC can do wirespeed forwarding with fq_codel on? Because with the 
setup I have, I don't see how there can be any buffering going on because 
it's a single gig port both in and out.

Mikael Abrahamsson    email: swmike at swm.pp.se

More information about the Cerowrt-devel mailing list