Peano

Searching...

No Matches

A hard coded strategy that can realise a few standard tasking patterns. More...

#include <Hardcoded.h>

Inheritance diagram for tarch::multicore::orchestration::Hardcoded:

[legend]

Collaboration diagram for tarch::multicore::orchestration::Hardcoded:

[legend]

Public Member Functions
	Hardcoded (int minTasksToFuse, int maxTasksToFuse, int deviceForFusedTasks, int maxNestedConcurrency, std::chrono::microseconds timeout)
	Construct hardcoded scheme.

virtual	~Hardcoded ()=default

virtual void	startBSPSection (int nestedParallelismLevel) override
	Notifies the strategy that we enter a BSP section.

virtual void	endBSPSection (int nestedParallelismLevel) override
	Notifies the strategy that we leave a BSP (fork-join) section.

virtual FuseInstruction	fuse (int taskType) override
	How many tasks to fuse and to which device to deploy.

virtual ExecutionPolicy	paralleliseForkJoinSection (int nestedParallelismLevel, int numberOfTasks, int taskType) override
	Determine how to handle/realise parallelisation within fork/join region.

virtual void	updateFuseStatistics (int taskType, int queueSize, double averageNumberOfPendingReadyTasksPerProcessTaskExecution, double probabilityThatTaskIsCompleted) override
	Update task fusion status.

Public Member Functions inherited from tarch::multicore::orchestration::Strategy
virtual	~Strategy ()=default

Static Public Member Functions
static Hardcoded *	createBSP ()
	If you want to use sole BSP, you effectively switch off the tasking.

static Hardcoded *	createNative ()
	Fall back to native tasking.

static Hardcoded *	createFuseAll (int numberOfTasksToFuse, bool fuseImmediately, bool processTasksWhileWaitingInBSPArea, int targetDevice)
	Create a strategy where tasks are always fused if possible given the configuration constraints.

Static Public Attributes
static constexpr int	NoNestedParallelism = 1

static constexpr std::chrono::microseconds	NoTimeout = std::chrono::microseconds(0)

Static Public Attributes inherited from tarch::multicore::orchestration::Strategy
static constexpr int	EndOfBSPSection = -1

Private Attributes
int	_minTasksToFuse

int	_maxTasksToFuse

int	_deviceForFusedTasks

int	_maxNestedConcurrency

std::chrono::microseconds	_timeout

Additional Inherited Members
Public Types inherited from tarch::multicore::orchestration::Strategy
enum class	ExecutionPolicy { RunSerially , RunParallel }
	Provide hint of execution policy. More...

Detailed Description

A hard coded strategy that can realise a few standard tasking patterns.

Definition at line 19 of file Hardcoded.h.

Constructor & Destructor Documentation

◆ Hardcoded()

tarch::multicore::orchestration::Hardcoded::Hardcoded	(	int	minTasksToFuse,
		int	maxTasksToFuse,
		int	deviceForFusedTasks,
		int	maxNestedConcurrency,
		std::chrono::microseconds	timeout )

Construct hardcoded scheme.

Please read through Task fusion strategies for some hints and remarks on the strategies.

Parameters

deviceForFusedTasks	Use tarch::multicore::Task::Host if you do not intend to use GPUs
maxNestedConcurrency	Pass in NoNestedParallelism if you don't want nested parallelism.
timeout	Pass in NoTimeout if you don't want timeouts.

Definition at line 43 of file Hardcoded.cpp.

Referenced by createBSP().

Here is the caller graph for this function:

◆ ~Hardcoded()

virtual tarch::multicore::orchestration::Hardcoded::~Hardcoded ( )

virtualdefault

Member Function Documentation

◆ createBSP()

tarch::multicore::orchestration::Hardcoded * tarch::multicore::orchestration::Hardcoded::createBSP ( )

static

If you want to use sole BSP, you effectively switch off the tasking.

Technically, this is realised by a strategy which enqueues all tasks that are spawned into the pending task queue. No tasks are handed over to the actual back-end. Therefore, the tasks will be done lazily upon demand within processPendingTasks().

Definition at line 7 of file Hardcoded.cpp.

References Hardcoded(), tarch::multicore::Task::Host, NoNestedParallelism, and NoTimeout.

Here is the call graph for this function:

◆ createFuseAll()

tarch::multicore::orchestration::Hardcoded * tarch::multicore::orchestration::Hardcoded::createFuseAll	(	int	numberOfTasksToFuse,
		bool	fuseImmediately,
		bool	processTasksWhileWaitingInBSPArea,
		int	targetDevice )

static

Create a strategy where tasks are always fused if possible given the configuration constraints.

Parameters

numberOfTasksToFuse	The remaining tasks(<numberOfTasksToFuse) will remain stuck in the background queue and will stay there until processed lazily.
fuseImmediately	Fuse right when they are spawned. Otherwise, tasks end up in a local queue. If a thread runs out of work, it looks into this queue and then fuses. So the fuse happens later, but it does not hold back any task production thread.
targetDevice	Non-negative number or tarch::multicore::Task::Host.

Definition at line 28 of file Hardcoded.cpp.

◆ createNative()

tarch::multicore::orchestration::Hardcoded * tarch::multicore::orchestration::Hardcoded::createNative ( )

static

Fall back to native tasking.

Native tasking means simply that we do not hold back any tasks but immediately map them onto native tasks.

Definition at line 17 of file Hardcoded.cpp.

References tarch::multicore::Task::Host.

Referenced by peano4::parallel::tests::PingPongTest::testMultithreadedPingPongWithBlockingReceives(), peano4::parallel::tests::PingPongTest::testMultithreadedPingPongWithBlockingSends(), peano4::parallel::tests::PingPongTest::testMultithreadedPingPongWithBlockingSendsAndReceives(), peano4::parallel::tests::PingPongTest::testMultithreadedPingPongWithNonblockingReceives(), peano4::parallel::tests::PingPongTest::testMultithreadedPingPongWithNonblockingSends(), and peano4::parallel::tests::PingPongTest::testMultithreadedPingPongWithNonblockingSendsAndReceives().

Here is the caller graph for this function:

◆ endBSPSection()

void tarch::multicore::orchestration::Hardcoded::endBSPSection ( int nestedParallelismLevel )

overridevirtual

Notifies the strategy that we leave a BSP (fork-join) section.

Implements tarch::multicore::orchestration::Strategy.

Definition at line 58 of file Hardcoded.cpp.

◆ fuse()

tarch::multicore::orchestration::Hardcoded::FuseInstruction tarch::multicore::orchestration::Hardcoded::fuse ( int taskType )

overridevirtual

How many tasks to fuse and to which device to deploy.

See also: Consult the page Task fusion strategies for recommendations and hints on task fusion strategies.; Consult the namespace documentation of tarch::multicore::taskfusion for details on the realisation of the task fusion.

Parameters

taskType Task type for which we want to know if to fuse or not.

Implements tarch::multicore::orchestration::Strategy.

Definition at line 60 of file Hardcoded.cpp.

◆ paralleliseForkJoinSection()

tarch::multicore::orchestration::Strategy::ExecutionPolicy tarch::multicore::orchestration::Hardcoded::paralleliseForkJoinSection	(	int	nestedParallelismLevel,
		int	numberOfTasks,
		int	taskType )

overridevirtual

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.

Parameters

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.

Implements tarch::multicore::orchestration::Strategy.

Definition at line 67 of file Hardcoded.cpp.

References tarch::multicore::orchestration::Strategy::RunParallel, and tarch::multicore::orchestration::Strategy::RunSerially.

◆ startBSPSection()

void tarch::multicore::orchestration::Hardcoded::startBSPSection ( int nestedParallelismLevel )

overridevirtual

Notifies the strategy that we enter a BSP section.

Implements tarch::multicore::orchestration::Strategy.

Definition at line 56 of file Hardcoded.cpp.

◆ updateFuseStatistics()

void tarch::multicore::orchestration::Hardcoded::updateFuseStatistics	(	int	taskType,
		int	queueSize,
		double	averageNumberOfPendingReadyTasksPerProcessTaskExecution,
		double	probabilityThatTaskIsCompleted )

overridevirtual

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.

Parameters

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.

Implements tarch::multicore::orchestration::Strategy.

Definition at line 81 of file Hardcoded.cpp.

Field Documentation

◆ _deviceForFusedTasks

int tarch::multicore::orchestration::Hardcoded::_deviceForFusedTasks

private

Definition at line 23 of file Hardcoded.h.

◆ _maxNestedConcurrency

int tarch::multicore::orchestration::Hardcoded::_maxNestedConcurrency

private

Definition at line 24 of file Hardcoded.h.

◆ _maxTasksToFuse

int tarch::multicore::orchestration::Hardcoded::_maxTasksToFuse

private

Definition at line 22 of file Hardcoded.h.

◆ _minTasksToFuse

int tarch::multicore::orchestration::Hardcoded::_minTasksToFuse

private

Definition at line 21 of file Hardcoded.h.

◆ _timeout

std::chrono::microseconds tarch::multicore::orchestration::Hardcoded::_timeout

private

Definition at line 25 of file Hardcoded.h.

Referenced by exahype2.Project.Project::set_timeout().

◆ NoNestedParallelism

constexpr int tarch::multicore::orchestration::Hardcoded::NoNestedParallelism = 1

staticconstexpr

Definition at line 62 of file Hardcoded.h.

Referenced by createBSP().

◆ NoTimeout

constexpr std::chrono::microseconds tarch::multicore::orchestration::Hardcoded::NoTimeout = std::chrono::microseconds(0)

staticconstexpr

Definition at line 63 of file Hardcoded.h.

Referenced by createBSP().

The documentation for this class was generated from the following files:

src/tarch/multicore/orchestration/Hardcoded.h
src/tarch/multicore/orchestration/Hardcoded.cpp

Public Member Functions

Static Public Member Functions

Static Public Attributes

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ Hardcoded()

◆ ~Hardcoded()

Member Function Documentation

◆ createBSP()

◆ createFuseAll()

◆ createNative()

◆ endBSPSection()

◆ fuse()

◆ paralleliseForkJoinSection()

◆ startBSPSection()

◆ updateFuseStatistics()

Field Documentation

◆ _deviceForFusedTasks

◆ _maxNestedConcurrency

◆ _maxTasksToFuse

◆ _minTasksToFuse

◆ _timeout

◆ NoNestedParallelism

◆ NoTimeout