Large interruptions for EAL thread running on isol core

[Stephen Hemminger]

On Thu, 23 Jun 2022 20:03:02 +0200
Antonio Di Bacco <a.dibacco.ks at gmail.com> wrote:

> I'm running a DPDK thread on an isolated core. I also set some  flags
> that could help keeping the core at rest on linux like: nosoftlockup
> nohz_full rcu_nocbs irqaffinity.
> 
> Unfortunately the thread gets some interruptions that stop the thread
> for about 20-30 micro seconds. This seems smal but my application
> suffers a lot.
> 
> I also tried to use  rte_thread_set_priority that indeed has a strong
> effect but unfortunately creates problems to Linux (like network not
> working).
> 
> Is there any other knob that could help running the DPDK thread with
> minimum or no interruptions at all?

Look with perf and see what is happening.
First check for interrupt affinity.
Don't try real time priority.

The other thing to look for would be any BIOS settings.
Some system management units can take away CPU silently for polling
some internal housekeeping.