 |
Peano
|
|
Peano
|
Interface for any task orchestration. More...
#include <Strategy.h>
Data Structures | |
| struct | FuseInstruction |
| Fuse instruction. More... | |
Public Types | |
| enum class | ExecutionPolicy { RunSerially , RunParallel } |
| Provide hint of execution policy. More... | |
Public Member Functions | |
| virtual | ~Strategy ()=default |
| virtual void | startBSPSection (int nestedParallelismLevel)=0 |
| Notifies the strategy that we enter a BSP section. | |
| virtual void | endBSPSection (int nestedParallelismLevel)=0 |
| Notifies the strategy that we leave a BSP (fork-join) section. | |
| virtual void | updateFuseStatistics (int taskType, int queueSize, double averageNumberOfPendingReadyTasksPerProcessTaskExecution, double probabilityThatTaskIsCompleted)=0 |
| Update task fusion status. | |
| virtual FuseInstruction | fuse (int taskType)=0 |
| How many tasks to fuse and to which device to deploy. | |
| virtual ExecutionPolicy | paralleliseForkJoinSection (int nestedParallelismLevel, int numberOfTasks, int taskType)=0 |
| Determine how to handle/realise parallelisation within fork/join region. | |
Static Public Attributes | |
| static constexpr int | EndOfBSPSection = -1 |
Interface for any task orchestration.
There are multiple orchestration strategies implementing this interface and hence guiding the task execution pattern. You can create those and make them live by calling tarch::multicore::setOrchestration().
Please consult the operation fuse() and its result type, FuseInstruction, for details on the exact decision process.
Definition at line 36 of file Strategy.h.
|
strong |
Provide hint of execution policy.
| Enumerator | |
|---|---|
| RunSerially | |
| RunParallel | |
Definition at line 48 of file Strategy.h.
|
virtualdefault |
|
pure virtual |
Notifies the strategy that we leave a BSP (fork-join) section.
Implemented in benchmarks::exahype2::ccz4::MulticoreOrchestration, tarch::multicore::orchestration::AllOnGPU, and tarch::multicore::orchestration::Hardcoded.
|
pure virtual |
How many tasks to fuse and to which device to deploy.
| taskType | Task type for which we want to know if to fuse or not. |
Implemented in tarch::multicore::orchestration::AllOnGPU, and tarch::multicore::orchestration::Hardcoded.
Referenced by tarch::multicore::taskfusion::ProcessReadyTask::processTasks(), tarch::multicore::taskfusion::ProcessReadyTask::run(), and tarch::multicore::taskfusion::translateFusableTaskIntoTaskSequence().
|
pure virtual |
Determine how to handle/realise parallelisation within fork/join region.
Peano models its execution with multiple parallel, nested fork/join sections. You could also think of these as mini-BSP sections. This routine guides the orchestration how to map those BSP sections onto tasks.
The decision can be guided by basically arbitrary contextual factors. The most important one for me is the nesting factor. As we work mainly with OpenMP, where tasks are tied to one core, it makes limited sense to have nested parallel fors. Notably, it makes stuff slower. So usually, I return ExecutionPolicy::RunSerially with anything with a nesting level greater than 1.
| nestedParallelismLevel | Please compare with tarch::multicore::spawnAndWait() which ensures that this flag equals 1 on the top level. A parameter of 0 would mean that no fork/join region has been opened. For such a parameter, the code would not query this function. |
| taskType | If we enter a fork-join section, this section logically spawns a set of tasks, which are all of the same type. So the task type here is given implicitly by the code location. But each BSP section has a unique identifier. |
Implemented in benchmarks::exahype2::ccz4::MulticoreOrchestration, tarch::multicore::orchestration::AllOnGPU, tarch::multicore::orchestration::Hardcoded, and tarch::multicore::orchestration::GeneticOptimisation.
|
pure virtual |
Notifies the strategy that we enter a BSP section.
Implemented in benchmarks::exahype2::ccz4::MulticoreOrchestration, tarch::multicore::orchestration::AllOnGPU, and tarch::multicore::orchestration::Hardcoded.
|
pure virtual |
Update task fusion status.
Feed orchestration with some stats around the task queue of interest. This routine is not called every time a process read tasks kicks off, but only every now and then. Furthermore, please note that this routine is invoked iff the orchestration beforehand had decided to fuse tasks.
| taskType | Number of the task that we are studying |
| queueSize | Size of the queue at this observation point |
| averageNumberOfPendingReadyTasksPerProcessTaskExecution | average over number of tasks in the queue whenever a process task has kicked off and the underlying real task has not completed yet. |
| probabilityThatTaskIsCompleted | Probability that task result has been there already when the corresponding instance of ProcessReadyTask fires up. This is a biased value: If we try to look up if a task is already completed and the underlying dictionary is locked, then this counts as a "no hit" as well. |
Implemented in tarch::multicore::orchestration::AllOnGPU, and tarch::multicore::orchestration::Hardcoded.
Referenced by tarch::multicore::taskfusion::ProcessReadyTask::run().
|
staticconstexpr |
Definition at line 130 of file Strategy.h.
1.10.0