Re: [WIP 0/3] Memory model and atomic API in Rust

Kent Overstreet
2024-03-23T00:21:48Z

On Fri, Mar 22, 2024 at 05:12:29PM -0700, Linus Torvalds wrote:
> On Fri, 22 Mar 2024 at 16:57, Kent Overstreet <kent.overstreet@linux.dev> wrote:
> >
> > I wonder about that. The disadvantage of only supporting LKMM atomics is
> > that we'll be incompatible with third party code, and we don't want to
> > be rolling all of our own data structures forever.
>
> Honestly, having seen the shit-show that is language standards bodies
> and incomplete compiler support, I do not understand why people think
> that we wouldn't want to roll our own.
>
> The C++ memory model may be reliable in another decade. And then a
> decade after *that*, we can drop support for the pre-reliable
> compilers.
>
> People who think that compilers do things right just because they are
> automated simply don't know what they are talking about.
>
> It was just a couple of days ago that I was pointed at
>
> https://github.com/llvm/llvm-project/issues/64188

Besides that there's cross arch support to think about - it's hard to
imagine us ever ditching our own atomics.

I was thinking about something more incremental - just an optional mode
where our atomics were C atomics underneath. It'd probably give the
compiler people a much more effective way to test their stuff than
anything they have now.