Tasking

To utilize the HiCR tasking frontend, we provide a simple runtime system.

Runtime

This runtime system is kept minimal and in the following section, we will explain the steps to set up this runtime system for HiCR tasking.

Initializing the runtime

The first step is to initialize the runtime itself. To do this, one needs to use two compute managers: one for the execution states (tasks) and one for the processing units (workers).

In the current version of HiCR, the following two configurations are acceptable ComputeManagers for this runtime:

Pthreads + Boost: pthreads compute manager is for kernel-level thread-based workers, and Boost is for coroutine-based tasks. The main advantage of using this setup is the quick user-level context switching, especially for fine-grained tasks.

HiCR::backend::pthreads::ComputeManager processingUnitComputeManager;
HiCR::backend::boost::ComputeManager    executionStateComputeManager;

nOS-V: The workers and tasks are wrapped in nOS-V tasks. nOS-V has the advantage of thread-level storage and co-execution of independent tasks. Coarse-grained tasks can have a benefit of it.

HiCR::backend::nosv::ComputeManager processingUnitComputeManager;
HiCR::backend::nosv::ComputeManager executionStateComputeManager;

After choosing the compute managers, one can initialize the runtime like this:

// Initializing the runtime with chosen ComputeManagers
Runtime runtime(&executionStateComputeManager, &processingUnitComputeManager);

Adding workers

The next step is to add as many processing units as available of your system. Each processing unit is linked to one worker.

// Creating a Processing Unit of the first available computeResource
auto ProcessingUnit = processingUnitComputeManager.createProcessingUnit(computeResources[0]);

// adding available compute resources
runtime.addProcessingUnit(ProcessingUnit);

Adding tasks

After the tasking workers have been initialized, the next step is to create the tasks. For this runtime system, we modified the task class to also include a unique label for execution dependencies. This label refers to the order in which the tasks have to be executed in this runtime system.

// Create a new tasks
uint64_t label = 0;
auto fc = [](void *arg){ printf("Hello, I am Task: %lu\n", ((Task *)arg)->getLabel()); };

auto MyTask = new Task(label,  fc);

runtime.addTask(MyTask);

Executing tasks

Finally, we can let the runtime execute the tasks.

// Running tasks
runtime.run();

Examples

The following examples use the runtime: