tc qdisc tbf: burst parameter

Hi everybody,

I am using TBF to limit the bandwidth in order to do some research
tasks on an Cloud Gaming platform.

Cloud Gaming delay requirements are very strict, so I need a plenty
control over latency that TBF induces to the stream.

I have read that in order to not induce any latency to the packets
(just dispath or drop, without any queue), "limit" has to be equal to
the "burst" parameter.

I have tested that it is not true, because when using a too big burst
and limit, RTT for the packet increase. So I read in the doc that to
achieve the minimum latency, I have to set the burst at the minimun
and  according to this equation:

Rate=burst*HZ.

Where "rate" is the output rate that is wanted to be achieved and Hz
is the user frequency of the linux Kernel. However, eve doing this i
am not able to get the desired rate. I even change the grub parameter
"nohz=off" to not have the idle kernel frequency mode and maintain a
constant frecuency of 250Hz (which it supposed my kernel works)


What I am missing in my approach? I am very stuck on this .. Could you
please help me? :)

This is the configuration I deduced from the exposition above to get a
5Mbit rate:

sudo tc qdisc add dev XXX root handle 1: prio
sudo tc qdisc add dev XXX parent 1:3 handle 30: \tbf rate 5mbit burst
2.5kb limit 2.5kb  mtu 1515 mpu 54b
sudo tc filter add dev XXX protocol ip parent 1:0 prio 3 u32 \match ip
src 11.22.33.444 flowid 1:3

Thanks in advance,

Alberto