Asynchronous Execution

In this exercise you will learn how to use different techniques for synchronizing commands and data.

1.) Waiting on events

Take a look at the vector add applications using the buffer/accessor model in the "Data Parallelism" exercise and the USM model in the "Using USM" exercise, and familiarize yourself with how they call wait on returned events to synchronize the completion of the work.

2.) Waiting on queues

With those same applications convert them to call wait on the queue to synchronize instead.

3.) Buffer destruction

Take a look at the vector add application using the buffer/accessor mode in the "Data Parallelism" exercise and how it synchronizes on the destruction of the buffers.

4.) Copy back

Take a look that two applications again and familiarize yourself with how the result of the computation is copied back to the host.

In the case of the application using the buffer/accessor model note how this occurs implicitly on the destruction of the buffer.

In the case of the application using the USM model note how this occurs explicitly by calling memcpy.

4.) Host accessor

Finally with the application which is using the buffer/accessor model introduce a host accessor by calling get_host_access on the buffer. The host accessor can be used to check the result of the computation on the host while the buffer is still alive.

Remember to do this within a scope to ensure the host accessor is destroyed.

Also note that creating a host accessor may copy the data back to the original pointer provided to the buffer but this is not guaranteed.

Build And Execution Hints

For DevCloud via JupiterLab follow these instructions.

For DPC++: instructions.

For AdaptiveCpp: instructions.