Re: [RFC 1/2] mm: disable LRU pagevec during the migration temporarily

[Matthew Wilcox]

On Wed, Feb 17, 2021 at 12:46:19PM -0800, Minchan Kim wrote:
> > I suspect you do not want to add atomic_read inside hot paths, right? Is
> > this really something that we have to microoptimize for? atomic_read is
> > a simple READ_ONCE on many archs.
> 
> It's also spin_lock_irq_save in some arch. If the new synchonization is
> heavily compilcated, atomic would be better for simple start but I thought
> this locking scheme is too simple so no need to add atomic operation in
> readside.

What arch uses a spinlock for atomic_read()?  I just had a quick grep and
didn't see any.