Re: Add spin_delay() implementation for Arm in s_lock.h

Hi,

> I landed on the idea of adding some intentional spinlock
> contention to src/test/modules/test_shm_mq, which is a prefab test
> framework for passing data among multiple worker processes.  The
> attached quick-hack patch makes it grab and release a spinlock once
> per passed message.

I wonder if this will show the full set of spinlock contention issues - isn't
this only causing contention for one spinlock between two processes? It's not
too hard to imagine delays being more important the more processes contend for
one cacheline.  I only skimmed your changes, so I might also just have
misunderstood what you were doing...

Greetings,

Andres Freund