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

On Wed, Feb 17, 2021 at 09:16:12PM +0000, Matthew Wilcox wrote:

On Wed, Feb 17, 2021 at 12:46:19PM -0800, Minchan Kim wrote:

quoted

quoted

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.

Ah, my bad. I was confused with update side.
Okay, let's use atomic op to make it simple.

Thanks for the review, Mattew and Michal.