Re: rt-tests: cyclictest: Add option to specify main pid affinity

On Mon, Feb 22, 2021 at 04:28:30PM +0100, Jonathan Schwender wrote:

Hi John,

This patch adds the option --mainaffinity to specify the affinity of
the main pid.
This is mainly useful if you want to bind the main thread to a
different (e.g. housekeeping ) CPU than the measurement threads.

Pardon my ignorance; can you please specify why is this important?
The measurement threads have an RT priority while the main thread is
SCHED_OTHER. So why would the cyclictest measurements really be affected
by the main thread (unless there's a preempt_rt bug)?

Do you also have any numbers showing different results with/without
"--mainaffinity"?

Thanks,

--
Ahmed S. Darwish