Load balancing

Load balancing#

The GauXC::LoadBalancer distributes quadrature tasks across processes and provides access to local work units. To create load balancers, the GauXC::LoadBalancerFactory is provided, which can generate different load balancing strategies based on user-defined settings. For specifying the execution context, the GauXC::ExecutionSpace enum is available.

class LoadBalancer#

A class to distribute and manage local quadrature tasks for XCIntegraor operations.

Public Functions

LoadBalancer()#

Construct default LoadBalancer instance with null internal state.

LoadBalancer(std::unique_ptr<pimpl_type> &&pimpl)#

Construct LoadBalancer instance from preconstructed implementation.

LoadBalancer(const LoadBalancer&)#

Copy a LoadBalancer instance.

LoadBalancer(LoadBalancer&&) noexcept#

Move a LoadBalancer instance.

~LoadBalancer() noexcept#

Destruct LoadBalancer instance (defaulted)

const std::vector<XCTask> &get_tasks() const#

Get underlying (local) quadrature tasks for this process (cost)

std::vector<XCTask> &get_tasks()#

Get underlying (local) quadrature tasks for this process (non-cost)

void rebalance_weights()#

Rebalance quadrature batches according to weight-only cost.

void rebalance_exc_vxc()#

Rebalance quadrature batches according to exc-vxc cost.

void rebalance_exx()#

Rebalance quadrature batches according to exx cost.

const util::Timer &get_timings() const#

Return internal timing tracker.

size_t total_npts() const#

Return the total number of points for local tasks.

size_t max_npts() const#

Return the maximum number of points for local tasks.

size_t max_nbe() const#

Return the maximum effective basis dimention for local tasks.

size_t max_npts_x_nbe() const#

Return the maximum npts x nde product for local tasks.

const Molecule &molecule() const#

Return the underlying molecule instance used to generate this LoadBalancer.

const MolMeta &molmeta() const#

Return the underlying MolMeta instance used to generate this LoadBalancer.

const basis_type &basis() const#

Return the underlying BasisSet instance used to generate this LoadBalancer.

const basis_map_type &basis_map() const#

Return BasisSetMap instance corresponding to basis/molecule.

const shell_pair_type &shell_pairs() const#

Return the number of non-negligible local shell pairs for this LoadBalancer.

const RuntimeEnvironment &runtime() const#

Return the runtime handle used to construct this LoadBalancer.

LoadBalancerState &state()#

Return the load balancer state (non-const)

bool operator==(const LoadBalancer&) const#

Check equality of LoadBalancer instances.

class LoadBalancerFactory#

A factory to generate LoadBalancer instances.

Public Functions

LoadBalancerFactory(ExecutionSpace ex, std::string kernel_name)#

Construct a factory which generates a specific kind of LoadBalancer.

Currently accepted values for Device execution space:

  • ”DEFAULT”: Read as “REPLICATED”

  • ”REPLICATED”: Same as Host::REPLICATED-PETITE

Parameters:

  • ex – [in] Execution space for the LoadBalancer phase. Acceptable values:

  • kernel_name – [in] Specification of the LoadBalancer kernel. Currently accepted values for Host execution space:

    • ”DEFAULT”: Read as “REPLICATED-PETITE”

    • ”REPLICATED”: Read as “REPLICATED-PETITE”

    • ”REPLICATED-PETITE”: Replicate the load balancer function, only keep non negligible basis functions

    • ”REPLICATED-FILLIN”: Same as “REPLICATED-PETITE” except if two non-adjacent bfns are kept, the gaps are filled in. This gurantees contiguous memory access but leads to significantly more work. Not advised for general usage

LoadBalancer get_instance(const RuntimeEnvironment &rt, const Molecule &mol, const MolGrid &mg, const BasisSet<double> &bs)#

Generate a LoadBalancer instance per kernel and execution space specfication.

Parameters:

  • rt – [in] Runtime handle defining the execution space across which the quadrature tasks will be distributed.

  • mol – [in] Molecule on which the quadrature is defined.

  • mg – [in] The batched molecular quadrature

  • bs – [in] The basis set whcih will be used for numerical integration

Returns:

A LoadBalancer instance constructed using the passed parameters.

std::shared_ptr<LoadBalancer> get_shared_instance(const RuntimeEnvironment &rt, const Molecule &mol, const MolGrid &mg, const BasisSet<double>&)#

Generate a shared pointer to a LoadBalancer instance per kernel and execution space specfication.

Parameters:

  • rt – [in] Runtime handle defining the execution space across which the quadrature tasks will be distributed.

  • mol – [in] Molecule on which the quadrature is defined.

  • mg – [in] The batched molecular quadrature

  • bs – [in] The basis set whcih will be used for numerical integration

Returns:

A shared pointer to a LoadBalancer instance constructed using the passed parameters.

enum class GauXC::ExecutionSpace#

Specification of the execution space for various operations.

Values:

enumerator Host#

Execute task on the host.

enumerator Device#

Execute task on the device (e.g. GPU)

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