Re: [PATCH RFC] Avoid memory barrier in read_seqcount() through load acquire

[Linus Torvalds]

On Tue, 13 Aug 2024 at 12:58, Waiman Long <longman@xxxxxxxxxx> wrote:
>
> Sorry for the confusion. What you said above is actually the reason that
> I ask this question. In the same way, smp_rmb()/wmb() is available for
> all arches. I am actually asking if it should be a flag that indicates
> the arch's preference to use acquire/release over rmb/wmb.

I think that if an arch says it has native acquire/release, we should
basically assume that it's the better model.

I mean, we could certainly use "PREFERS" instead of "HAS", but is
there any real reason to do that?

Do we suddenly expect that people would make a CPU that has native
acquire/release, and it would somehow then prefer a full read barrier?

             Linus