What is a memory fence?
What is meant by using an explicit memory fence? ...
memory-fences
Atomic Instructions and Variable Update visibility
On most common platforms (the most important being x86; I understand that some platforms have extremely difficult memory models that provide almost no guarantees useful for multithreading, but I don't care about rare counter-examples), is the following code safe? Thread 1: someVariable = doStuff(); atomicSet(stuffDoneFlag, 1); Thread...
When do writes/reads affect main memory?
When I write a value into a field, what guarantees do I get regarding when the new value will be saved in the main memory? For example, how do I know that the processor don't keep the new value in it's private cache, but updated the main memory? Another example: int m_foo; void Read() // executed by thread X (on processor #0) { Co...
.NET memory model, volatile variables, and test-and-set: what is guaranteed?
I know that the .NET memory model (on the .NET Framework; not compact/micro/silverlight/mono/xna/what-have-you) guaranteed that for certain types (most notably primitive integers and references) operations were guaranteed to be atomic. Further, I believe that the x86/x64 test-and-set instruction (and Interlocked.CompareExchange) actuall...
Memory Fences - Need help to understand
Hello all, I'm reading Memory Barriers by Paul E. McKenney http://www.rdrop.com/users/paulmck/scalability/paper/whymb.2010.07.23a.pdf everything is explained in great details and when I see that everything is clear I encounter one sentence, which stultifies everything and make me think that I understood nothing. Let me show the example ...
Memory ordering issues
I'm experimenting with C++0x support and there is a problem, that I guess shouldn't be there. Either I don't understand the subject or gcc has a bug. I have the following code, initially x and y are equal. Thread 1 always increments x first and then increments y. Both are atomic integer values, so there is no problem with the increment ...