Atomic operations

Hi,

I'm reading some of the C++ working standard, and I arrive at the chapter on Atomic Operations Library.

Are these types/operations which will never be split over various threads, i.e., thread-safe types and operations?

If that's true, why are there types like "atomic_bool" ? A normal primitive 'bool' is already type safe?

Further, could someone explain me some of the applications? Massive parallel for example?


Thanks for your explications!!!


Mark

Being type-safe and thread-safe are completely different concepts.

> Further, could someone explain me some of the applications?
Anything involving threads.
On a single CPU, the granularity is a single instruction.
On a multi-CPU system, the granularity is a bus cycle.

What the atomic types guarantee is that the objects will still do the right thing, despite the increased opportunity for interleaving the actions of multiple CPUs.

Quote:

---

Originally Posted by Salem

On a single CPU, the granularity is a single instruction.

---

That's no longer true with multi-core CPUs.

I'd say that "single CPU" means "Single core" - Multi-CPU systems are those with more than one processing unit, no matter if that is provided through a single chip or multiple chips.

Note that for example a single-core CPU with an "intelligent"[1] graphics processor, is also a "multiprocessor" system. Although it is of course only relevant for data shared between the CPU and the GPU.

[1] Literally anything more advanced than the VGA graphics adapters, and certainly ALL of the 3D graphics cards are "intelligent" in this context.

--
Mats