toolbox::loadbalancing::strategies::SpreadOut Class Reference

Spread out. More...

#include <SpreadOut.h>

Inheritance diagram for toolbox::loadbalancing::strategies::SpreadOut:

Collaboration diagram for toolbox::loadbalancing::strategies::SpreadOut:

Public Member Functions
	SpreadOut (Configuration *configuration=new DefaultConfiguration(), CostMetrics *costMetrics=new toolbox::loadbalancing::metrics::CellCount())
virtual	~SpreadOut ()
virtual void	finishStep () override
	Finish the step.
Public Member Functions inherited from toolbox::loadbalancing::AbstractLoadBalancing
	AbstractLoadBalancing (Configuration *configuration, CostMetrics *costMetrics)
	Constructor.
virtual	~AbstractLoadBalancing ()
	Destructor.
virtual std::string	toString () const
	Create a string representation of load balancing object.
virtual void	enable (bool)
	Switch on/off.
virtual bool	hasSplitRecently () const
	Has mesh split recently.
bool	isEnabled (bool globally) const
	Is load balancing enabled.
virtual int	getGlobalNumberOfTrees () const
	Delegate to stats.
virtual bool	hasStagnated () const
	A load balancing can either be stagnating or be switched off for this predicate to hold.
virtual void	finishSimulation ()
void	setConfigurationAndMetricsNullWithoutDelete ()
	This is only used when you concatenate balancing rules and you want to disable any deletion.

Private Member Functions
int	getNumberOfTreesPerRank () const
	Return 0 if the load balancing should not split (yet) and otherwise return number of splits required.
void	updateLoadBalancing ()
void	triggerSplit (int numberOfCells, int targetRank)

Static Private Attributes
static tarch::logging::Log	_log

Additional Inherited Members
Static Public Attributes inherited from toolbox::loadbalancing::AbstractLoadBalancing
static constexpr int	NoHeaviestTreeAvailable = -1
	Is used by tree identification and either indicates that there are no trees at all or means that the heaviest tree is on the blacklist.
static constexpr int	NumberOfMeshSweepsAfterSplitToMakeMeshConsistentAgain = 3
	Number of mesh sweeps a split needs until the mesh is consistent again.
Protected Member Functions inherited from toolbox::loadbalancing::AbstractLoadBalancing
bool	fitsIntoMemory (State state) const
	Ensure enough memory is left-over.
bool	isInterRankBalancingBad () const
	Is the balancing between the ranks ok.
bool	isIntraRankBalancingBad () const
	Is the balancing on the rank ok.
bool	areRanksUnemployed () const
double	getWeightOfHeaviestLocalSpacetree () const
int	getIdOfHeaviestLocalSpacetree () const
	Determines the maximum spacetree size a tree should have in the optimal case.
int	getIdOfHeaviestLocalSpacetree (double tolerance) const
	Similar to getIdOfHeaviestLocalSpacetree() but you might get one of the trees back that is close to the heaviest one up to tolerance.
Protected Attributes inherited from toolbox::loadbalancing::AbstractLoadBalancing
Blacklist	_blacklist
Statistics	_statistics
Configuration *	_configuration
CostMetrics *	_costMetrics
State	_state
	Ensure that you invoke.
Static Protected Attributes inherited from toolbox::loadbalancing::AbstractLoadBalancing
static tarch::logging::Log	_log

Detailed Description

Spread out.

Try to give each thread on each rank one tree in one big decomposition rush. After that, switch into stagnation.

The routine tries to get as many cores/ranks in as possible. Therefore, we employ a bottom-up splitting strategy which prioritises fair fine grid splits over an "efficient" tree decomposition. Consult a discussion of splitting variants and constraints in peano4::grid::Spacetree::isCellTopDownSplitCandidate() and peano4::grid::Spacetree::isCellBottomUpSplitCandidate(), peano4::grid::Spacetree::splitOrJoinCell() and notably the general domain decomposition overview for the rationale.

Definition at line 44 of file SpreadOut.h.

Constructor & Destructor Documentation

SpreadOut()

toolbox::loadbalancing::strategies::SpreadOut::SpreadOut	(	Configuration *	configuration = new DefaultConfiguration(),
		CostMetrics *	costMetrics = new toolbox::loadbalancing::metrics::CellCount()
	)

~SpreadOut()

virtual toolbox::loadbalancing::strategies::SpreadOut::~SpreadOut ( )

virtual

Member Function Documentation

finishStep()

virtual void toolbox::loadbalancing::strategies::SpreadOut::finishStep ( )

overridevirtual

Finish the step.

No matter what you do here, you have to invoke

     _statistics.updateGlobalView();
     _blacklist.update();

in this routine.

If you use the actionset toolbox.laodbalancing.api.LoadBalancing, then the unprepareTraversal() invokes the finishStep() for you. This in turn means, as per contract, that the statistics have an updated global view.

Implements toolbox::loadbalancing::AbstractLoadBalancing.

getNumberOfTreesPerRank()

int toolbox::loadbalancing::strategies::SpreadOut::getNumberOfTreesPerRank ( ) const

private

Return 0 if the load balancing should not split (yet) and otherwise return number of splits required.

There are two reasons to split:

• The mesh is stable, i.e. the grid statistics of peano4::parallel::SpacetreeSet::getGridStatistics() report that no vertex has been refined and no refinement has been triggered in the most recent traversal. In this case, we split up as aggressively as the minimal tree size permits, even if we cannot keep all cores busy. As the grid statistics are reduced over all ranks, all ranks agree on this criterion.
• The mesh is already big enough to give every core on every rank a tree of at least the minimal tree size.

triggerSplit()

void toolbox::loadbalancing::strategies::SpreadOut::triggerSplit ( int  numberOfCells, int  targetRank  )

private

updateLoadBalancing()

void toolbox::loadbalancing::strategies::SpreadOut::updateLoadBalancing ( )

private

Field Documentation

_log

tarch::logging::Log toolbox::loadbalancing::strategies::SpreadOut::_log

staticprivate

Definition at line 55 of file SpreadOut.h.

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

• src/toolbox/loadbalancing/strategies/SpreadOut.h