Class Environment

Class Documentation

class qhipster::mpi::Environment

A trimmed down version of the BOOST::MPI environment. Its purpose is to initialize the MPI library and partition the cluster or single threaded environment for parallel operations. In preparation of the Monte-Carlo simulations required for the noisy implementation, we provide a communicator over the ranks involved in a single MC simulation.

Specifically, we store two communicators:

  1. pool_communicator: spanning all the useful ranks

  2. state_communicator: spanning those ranks used in a single MC simulation (i.e. state)

Public Functions

Environment(int &argc, char **&argv)

Intialize the MPI Environment.

It receives the same argc and argv arguments passed to the main function. If MPI is present, but has not been initialized, then MPI_Init will be called.

~Environment()

Finalize the MPI Environment

If MPI is present and has been initizlized in the constructor then MPI_Finalize will be called here.

Environment(Environment const&) = delete
Environment &operator=(Environment const&) = delete

Public Static Functions

void UpdateStateComm(int num_states, bool do_print_info = true)

Update the state and pool communicators.

Pre

This can only be called when all ranks are still active.

bool IsUsefulRank()

Check whether the rank is useful or not.

int GetPoolRank()

The rank of the current MPI process: pool or state.

The PoolRank may not corresponds to that from MPI_COMM_WORLD due to dummy ranks. The rank is 0 if MPI is not present.

Pre

If MPI is present, this can only be called after intializing MPI.

int GetStateRank()
int GetRank()
int GetPoolSize()

Number of MPI processes.

The PoolSize may not corresponds to that from MPI_COMM_WORLD due to dummy ranks. The number of processes is 1 if MPI is not present.

Pre

If MPI is present, this can only be called after intializing MPI.

int GetStateSize()
int GetSize()
template<class Type>
Type IncoherentSumOverAllStatesOfPool(Type local_value)

Get incoherent average over all states of the pool.

Parameters

  • local_value: the address of the value stored in the local rank.

int GetNumRanksPerNode()
int GetNumNodes()
int GetNodeId()
int GetStateId()
int GetNumStates()
void RemapStateRank(int newme)