Re: [PATCH 27/34] sched_ext: Implement SCX_KICK_WAIT

Linus Torvalds
2023-07-13T18:33:20Z

On Thu, 13 Jul 2023 at 06:46, Andrea Righi <andrea.righi@canonical.com> wrote:
>
> I'm not sure if we already have an equivalent of
> smp_store_release_u64/smp_load_acquire_u64(). Otherwise, it may be worth
> to add them to a more generic place.

Yeah, a 64-bit atomic load/store is not necessarily even possible on
32-bit architectures.

And when it *is* possible, it might be very very expensive indeed (eg
on 32-bit x86, the way to do a 64-bit load would be with "cmpxchg8b",
which is ridiculously slow)

Linus