Interlocked.MemoryBarrierProcessWide Method
Definition
Important
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Provides a process-wide memory barrier that ensures that reads and writes from any CPU cannot move across the barrier.
public:
static void MemoryBarrierProcessWide();public static void MemoryBarrierProcessWide ();static member MemoryBarrierProcessWide : unit -> unitPublic Shared Sub MemoryBarrierProcessWide ()Remarks
The MemoryBarrierProcessWide method differs from the "normal" MemoryBarrier method as follows:
The normal memory barrier ensures that the reads and writes from the current CPU can't move across the barrier. The process-wide memory barrier ensures that any read or write from any CPU being used in the process can't move across the barrier.
The normal memory barrier allows reasonable shared access if every thread accessing the data uses barriers. The process-wide memory barrier forces other CPUs to synchronize with process memory (for example, to flush write buffers and synchronize read buffers). This allows for non-interlocked operations on some threads and still have reasonable shared access.
The normal memory barrier imposes very little overhead; normal interlocked operations probably cost fewer than a hundred cycles. The process-wide memory barrier is very expensive. It has to force every CPU in the process do to something, at a probable cost of thousands of cycles.
The MemoryBarrierProcessWide method also suffers from all the subtleties of lock-free programming. Nevertheless, this method can be extremely useful when you actually need to call it, which should be rare.
This method wraps a call to FlushProcessWriteBuffers on Windows and sys_membarrier on Linux.
