Scheduler

General scheduling of work

The scheduler component vt::sched::Scheduler, accessed via vt::theSched(), holds pieces of work to execute later that may be prioritized. The scheduler polls the vt components to make progress and collect new pieces of work. The scheduler allows registration of callbacks when the system is idle.

Calls to the scheduler

To advance the scheduler, one should use:

vt::theSched()->runSchedulerWhile(/*std::function<bool()> cond*/);

This function polls (while cond is true) every component that might generate or complete work, and potentially runs one piece of available work, while also ensuring proper event unwinding and idle time tracking.

Higher-level Calls to Wait for Completion

If work is enclosed in an "epoch", the Termination Detector can be used to track its distributed completion. In this case, instead of calling the scheduler directly, built-in higher-level functions can be used to advance the scheduler until this work is complete/terminated.

To run the scheduler until an epoch terminates, call the following function:

vt::runSchedulerThrough(my_epoch);

Or, to combine the actual enclosed work with the call to wait for its termination, use the following function:

vt::runInEpochRooted([]{
  // work to do on a single node
});

If the work should be executed by all nodes, use a collective epoch:

vt::runInEpochCollective([]{
  // work to do on all nodes
});