[dpdk-dev] [PATCH] testpmd: add nanosleep in main loop

[Daniel Bristot de Oliveira]

On 11/10/2017 11:14 AM, Ananyev, Konstantin wrote:
> Agree with Adrian here - the patch doesn't fix the problem in any case,

I would agree with you if it were possible to assume one can fully
isolate a CPU on Linux... but it is not...

This:
https://lwn.net/Articles/659490/

is still an open issue, and the reason why it is an open issue is the
kernel threads that need to run on every CPU, mainly when using the
PREEMPT_RT, which turns almost everything on threads.

> while introducing an unnecessary slowdown in testpmd iofwd mode.
> Please think up some other approach.

The other approach is to increase the priority of all other threads that
run on the isolate CPU. But that is not a good idea at all, as the other
threads might preempt the busy-loop thread at the worst possible moment.

Using the knowledge of the thread about when it is the best time to give
a chance for other threads to run would be a smarter decision.

-- Daniel