Look free ID genertion (was: Is there a more efficient threading lock?)

[Chris Angelico]

On Thu, 2 Mar 2023 at 08:01, <2QdxY4RzWzUUiLuE at potatochowder.com> wrote:
>
> On 2023-03-01 at 14:35:35 -0500,
> avi.e.gross at gmail.com wrote:
>
> > What would have happened if all processors had been required to have
> > some low level instruction that effectively did something in an atomic
> > way that allowed a way for anyone using any language running on that
> > machine a way to do a simple thing like set a lock or check it?
>
> Have happened?  I don't know about "required," but processors have
> indeed had such instructions for decades; e.g., the MC68000 from the
> early to mid 1980s (and used in the original Apple Macintosh, but I
> digress) has/had a Test and Set instruction.

As have all CPUs since; it's the only way to implement locks (push the
locking all the way down to the CPU level).

ChrisA