RFC abstracting atomics

[Bruce Richardson]

On Mon, Jan 09, 2023 at 02:56:04PM -0800, Tyler Retzlaff wrote:
> hi folks,
> 
> i would like to introduce a layer of abstraction that would allow
> optional use of standard C11 atomics when the platform / toolchain
> combination has them available.
> 
> making the option usable would be a phased approach intended to focus
> review and minimize dealing with churn on such a broad change.
> 
> 1. provide an initial series to add the abstraction and the ability
>    control enablement with a meson option enable_stdatomics=false will
>    be the default.
> 
>    for all existing platform / toolchain combinations the default would
>    remain false. i.e. i have no plans to enable it for existing platforms
>    toolchain combinations but leaves a change of default open to the
>    community as a future discussion if it is desired.
> 
> 2. once the initial abstraction is integrated a series will be introduced to
>    port the tree to the abstraction with enable_stdatomics=false. the goal
>    being low or no change to the current use of gcc builtin C++11 memory
>    model atomics.
> 
> 3. once the tree is ported a final series will be introduced to introduce
>    the remaining change to allow the use of enable_stdatomics=true.
> 
> would appreciate any assistance / suggestions you can provide to
> introduce the abstraction smoothly.
> 

Plan generally sounds ok. However, beyond point #3, would there then be
plans to remove the option and always use stdatomics in future?

To slightly expand the scope of the discussion - would it be worthwhile
putting these abstractions in a new library in DPDK other than EAL, to
start the process of splitting out some of the lower-level material from
that library?

/Bruce