Re: [B.A.T.M.A.N.] is the multicast performance throttled?

["Linus Lüssing" <linus.luessing@c0d3.blue>]

Hi Ignacio,

Could you describe your setup a little more, just two devices?
What hardware are you using, which wifi cards? Which operating
system and version?

Which version of batman-adv are you using? What is your kernel
version?

What is a typical bitrate your wifi cards are agreeing on (iw
station dump)? What multicast rate have you configured for your
wifi cards?

What software are you using for testing? What is the bitrate you
have configured in there? Is the unicast test UDP as well? What
bitrates are you able to achieve via TCP? Does a lower payload
length make any difference?

Regards, Linus


On Thu, Aug 11, 2016 at 05:13:01PM +0200, Ignacio Quezada wrote:
> Hello,
> I am trying to build an application using UDP multicast sockets based
> on a network mesh built with devices connected in IBSS mode. 
> 
> The kernel documentation says that this was the place to ask questions
> or anything :).
> 
> Testing the application in the mentioned environment, it suffers some
> kind of throttling or buffering limiting the throughput. Testing with
> my application, without the batman interface, just 2 IBSS connected
> devices, the multicast rate goes around 100kb/s (not saying that the
> wifi link actually tops at that speed), but then just to add the
> batman-adv interface and use that instead, the multicast rate becomes
> unstable between 0-20kb/s.
> 
> Disabling multicast optimization, it changes a bit the behaviour but
> still the same speed.
> 
> If I change the multicast packet to a unicast packet, both setups
> achieve the same speed (~100kb/s), so the batman interface is working
> but the multicast packets are being handled in a different way. Is it
> supposed to be like that?
> 
> The packets are sent right away according to the iptables counter of
> packets as well as tcpdump, but the receiver only gets them in a very
> slow way (counting but not calculating, I think it is around 8 packets
> per second).
> The MTU is set as advised, 1532 and the payload for the UDP packets is
> as big as it can be so the packet does not get fragmented.
> 
> Any way to increase the rate or disabling the throttling?
> -- 
> 
> MVH
> Ignacio Quezada