Which CPU architectures support Compare And Swap (CAS)?

multithreading multicore atomic cpu-architecture
paxos1977 picture paxos1977 · Sep 30, 2008 · Viewed 15.1k times · Source

just curious to know which CPU architectures support compare and swap atomic primitives?

Answer

jdkoftinoff picture jdkoftinoff · Sep 30, 2008

Powerpc has more powerful primitives available: "lwarx" and "stwcx"

lwarx loads a value from memory but remembers the location. Any other thread or cpu that touches that location will cause the "stwcx", a conditional store instruction, to fail.

So the lwarx /stwcx combo allows you to implement atomic increment / decrement, compare and swap, and more powerful atomic operations like "atomic increment circular buffer index"

Related questions

Forcing multiple threads to use multiple CPUs when they are available

I'm writing a Java program which uses a lot of CPU because of the nature of what it does. However, lots of it can run in parallel, and I have made my program multi-threaded. When I run it, it only …

Read More
Threads & Processes Vs MultiThreading & Multi-Core/MultiProcessor : How they are mapped?

I was very confused but the following thread cleared my doubts: Multiprocessing, Multithreading,HyperThreading, Multi-core But it addresses the queries from the hardware point of view. I want to know how these hardware features are mapped to software? One thing …

Read More
Multithreading and multicore differences

I have a couple of small questions. Firstly is there a difference between multithreading and multicore? Are they two completely different things or does multithreading use more than one core if it needs? Secondly Most cores have two threads but …

Read More