[netperf-talk] global question concerning Netperf test and SMP support

[Simon Duboue]

Hello everyone,

I am quite new in the Netperf community but I follow actively this talk.

I'm using netperf 2.4 to test a multi core platform with a 10G NIC.
I have a host which is based on a 8 cores SoC and with a Linux SMP 3.0 and 
a client based on a dual core motherboard with a Suse 11.

First, I have a question concerning the test of the loopback local 
interface (lo):
-how could we interpret the results provided by Netperf in term of 
throughput? is it limiting for the rest of the test concerning the 
network?

Then concerning the network test itself, I get a maximal throughput of 4 
Gbits/s with a unidirectional UDP STREAM test from client to host.
I am waiting more than that (8-9 GBit/s) and I am asking what could be 
limiting. I am already performing Jumbo frames and I suppose that Linux 
kernel are auto tuned concerning buffer and socket. I try to tune Linux by 
increasing the max buffer size but the effects are quite limited. I also 
modify timestamps, arp filtering and once again the effects are limited.

In TCP STREAM test, I also run two tests: a standard TCP STREAM and a 
standard TCP MAERTS and the results are very different with a 10x ratio 
for the TCP MAERTS. How is it possible?

The last question concerns the implementation of TCPIP stack in Linux 
kernel. Does it fully perform SMP or does TCPIP stack is reserved to a 
defined core.

I hope being clear. If not, please consider these mistakes as beginner 
ones.

Thank you in advance.

Simon Duboué
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