cuda::binary_semaphore
Defined in header <cuda/semaphore>:
namespace cuda {
template <cuda::thread_scope Scope>
using binary_semaphore = cuda::std::counting_semaphore<Scope, 1>;
}
The class template cuda::binary_semaphore is an extended form of cuda::std::binary_semaphore that takes an additional cuda::thread_scope argument. cuda::binary_semaphore has the same interface and semantics as cuda::std::binary_semaphore, but cuda::binary_semaphore is a class template.
Concurrency Restrictions
An object of type cuda::binary_semaphore or cuda::std::binary_semaphore, shall not be accessed concurrently by CPU and GPU threads unless:
- it is in unified memory and the
concurrentManagedAccessproperty is 1, or - it is in CPU memory and the
hostNativeAtomicSupportedproperty is 1.
Note, for objects of scopes other than cuda::thread_scope_system this is a data-race, and thefore also prohibited regardless of memory characteristics.
Under CUDA Compute Capability 6 (Pascal) or prior, an object of type cuda::binary_semaphore or cuda::std::binary_semaphore may not be used.
Implementation-Defined Behavior
For each cuda::thread_scope S, cuda::binary_semaphore<S>::max() is as follows:
cuda::thread_scope S | cuda::binary_semaphore<S>::max() |
|---|---|
| Any | 1 |
Example
#include <cuda/semaphore>
__global__ void example_kernel() {
// This semaphore is suitable for all threads in the system.
cuda::binary_semaphore<cuda::thread_scope_system> a;
// This semaphore has the same type as the previous one (`a`).
cuda::std::binary_semaphore<> b;
// This semaphore is suitable for all threads on the current processor (e.g. GPU).
cuda::binary_semaphore<cuda::thread_scope_device> c;
// This semaphore is suitable for all threads in the same thread block.
cuda::binary_semaphore<cuda::thread_scope_block> d;
}