Strategy that tries to assign chunks in a balanced manner without arbitrarily cutting chunks. More...

#include <ChunkInfo.hpp>

Inheritance diagram for openPMD::chunk_assignment::BinPacking:

Public Member Functions
	BinPacking (size_t splitAlongDimension=0)

Assignment	assign (PartialAssignment, RankMeta const &in, RankMeta const &out, size_t my_rank, size_t num_ranks) override
	Assign chunks to be loaded to reading processes.

virtual std::unique_ptr< Strategy >	clone () const override

Public Member Functions inherited from openPMD::chunk_assignment::Strategy
Assignment	assign (ChunkTable chunkTable, RankMeta const &in, RankMeta const &out, size_t my_rank, size_t num_ranks)
	Assign chunks to be loaded to reading processes.

Public Attributes
size_t	splitAlongDimension = 0

Detailed Description

Strategy that tries to assign chunks in a balanced manner without arbitrarily cutting chunks.

Idea: Calculate the ideal amount of data to be loaded per parallel process and cut chunks s.t. no chunk is larger than that ideal size. The resulting problem is an instance of the Bin-Packing problem which can be solved by a factor-2 approximation, meaning that a reading process will be assigned at worst twice the ideal amount of data.

Constructor & Destructor Documentation

◆ BinPacking()

openPMD::chunk_assignment::BinPacking::BinPacking ( size_t splitAlongDimension = 0 )

Parameters

splitAlongDimension If a chunk needs to be split, split it along this dimension.

Member Function Documentation

◆ assign()

Assignment openPMD::chunk_assignment::BinPacking::assign	(	PartialAssignment	partialAssignment,
		RankMeta const &	in,
		RankMeta const &	out,
		size_t	my_rank,
		size_t	num_ranks )

overridevirtual

Assign chunks to be loaded to reading processes.

To be defined by implementors.

Parameters

partialAssignment	Two chunktables, one of unassigned chunks and one of chunks that might have already been assigned previously. Merge the unassigned chunks into the partially assigned table.
in	Meta information on writing processes, e.g. hostnames.
out	Meta information on reading processes, e.g. hostnames.
my_rank	Rank identifier for the current process. Will be considered by some distribution strategies that may be called for only a subselection of the data space (e.g. for distributing data within processes on the same compute node in a cluster).
num_ranks	Number of processes among which chunks are to be distributed. Will be considered by some distribution strategies that may be called for only a subselection of the data space (e.g. for distributing data within processes on the same compute node in a cluster).

Returns: A table that assigns chunks to reading processes. Chunks are sorted by the destination process ID (MPI rank). Distribution strategies will in general only need to fill the chunks for the current (calling) process ID, but some (such as RoundRobin) will fill the information for other processes as well.

Implements openPMD::chunk_assignment::Strategy.

◆ clone()

std::unique_ptr< Strategy > openPMD::chunk_assignment::BinPacking::clone ( ) const