SCTP performance on 4.4.x Kernel with two instances of iperf3

[Deepak Khandelwal <dazz.87@gmail.com>]

Hi,

I am testing SCTP performance on 4.4.x mips kernel (Octeon 2 hardware)
I have a specific requirement of testing 130K packets per second with
each packet size of 278 bytes. Server(s) and Client(s) are running on
separate machines each with 16 CPU Core.

I am running two instances of iperf3 Server and client in those
dedicated machines respectively.
Is there any dependency between two instances from SCTP PoV ?

Case -1: when Running with one instance of Server and Client

./iperf3 --sctp -4 -c 18.18.18.1 -B 18.18.18.2 -p 45000 -V -l 278 -t 60 -A 10


I am getting consistent bandwidth.
CPU usage of Client is 100 %


Case -2:  when Running with two instances of Server and Client

./iperf3 --sctp -4 -c 18.18.18.1 -B 18.18.18.2 -p 45000 -V -l 278 -t 60 -A 10

./iperf3 --sctp -4 -c 18.18.18.1 -B 18.18.18.2 -p 45020 -V -l 278 -t 60 -A 11


the bandwidth is not consistent and sometimes even 0 .
CPU of both these process together reaches to 100% not individually.
so if one client CPU usage is 80% other one CPU usage is 20%

I have pinned the servers and clients to dedicated CPU cores. and
softirq interrupts also are masked to these cores.(smp_affinity)

I tried changing scheduling priority of these process to SCHED_RR
(earlier SCHED_OTHER)
but the situation is still the same.


Best Regards,
Deepak