[zeromq-dev] PUB/SUB Latency tests on PREEMPT_RT (with Hackbench)

LAO Sarah Sarah.lao at esg-group.fr
Tue Jul 1 14:57:01 CEST 2014


I am using ZeroMQ in a project on Linux PREEMPT_RT.
I have 2 modules A and B exchanging messages using PUB/SUB sockets.
A sends a message to B, B receives it, then B sends back another message 
to A.

The test is to measure with an oscilloscope the latency between module A 
sending a message to module B and module A receiving the message sent by B.

I did 2 kind of tests, one without using Hackbench, and one using Hackbench.

The first test, I executed my 2 modules, and got a "stable" latency 
(between 14ms and 16ms).

The second test, I executed my 2 modules, and also Hackbench with this 
hackbench -s 512 -l 600 -g 15 -f 25 -P
Now, several times, I got some "peaks" at 25ms, 50ms...

Have you any ideas of why I get theses results with hackbench?

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