5.3. Memory management

The CPU and GPU in a APU share the same main memory. There is no distinction between CPU and GPU memory. Even though a HSA kernel can directly consume any data in the main memory, it is recommended to register a memory region to the HSA runtime compatibility with HSA-compliant discrete GPUs.


Register every given array. The function can be used in a with-context for automically deregistration:

array_a = numpy.arange(10)
array_b = numpy.arange(10)
with hsa.register(array_a, array_b):
    some_hsa_code(array_a, array_b)

Deregister every given array

5.3.1. Shared memory and thread synchronization

A limited amount of shared memory can be allocated on the device to speed up access to data, when necessary. That memory will be shared (i.e. both readable and writable) amongst all workitems belonging to a given group and has faster access times than regular device memory. It also allows workitems to cooperate on a given solution. You can think of it as a manually-managed data cache.

The memory is allocated once for the duration of the kernel, unlike traditional dynamic memory management.

numba.hsa.shared.array(shape, type)

Allocate a shared array of the given shape and type on the device. This function must be called on the device (i.e. from a kernel or device function). shape is either an integer or a tuple of integers representing the array’s dimensions. type is a Numba type of the elements needing to be stored in the array.

The returned array-like object can be read and written to like any normal device array (e.g. through indexing).

A common pattern is to have each workitem populate one element in the shared array and then wait for all workitems to finish using :func:` .barrier`.


The scope argument specifies the level of synchronization. Set scope to 1 to synchronize all workitems in the same workgroup.