Enqueueing a Kernel

In this first exercise you will learn how to enqueue your first kernel function to run on a device and print Hello World! to the console.

1.) Create a queue

The first thing you must do is create a queue to submit work to. The simplest way to do this is to default construct it, this will choose a device for you.

2.) Define a command group

Once you have a queue you can now submit work to be executed on the device that queue is targeting and this is done via a command group.

Define a lambda expression which takes a reference to a handler to represent your command group function and pass it to the submit member function of the queue.

Note that submitting a command group without any commands will result in an error.

3.) Define a SYCL kernel function

Within the command group function define a SYCL kernel function via the single_task command within the command group, which takes only a function object which itself doesn't take any parameters.

Remember to declare a class for your kernel name in the global namespace. While it is possible to leave the class declaration inline in the handler scope, this can produce long kernel names that show up in profiler and debugger output and make it harder to use. Defining the kernel names out of local scope avoids this.

Also remember to call wait on the event returned from submit to await the completion of the kernel function.

4.) Stream "Hello World!" to stdout

Create a stream object within the command group scope. The parameters to the constructor of the stream class are the total buffer size, the work-item buffer size and the handler.

Then use the stream you constructed within the SYCL kernel function to print "Hello world!" using the << operator.

Build And Execution Hints

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