Operation-specific benchmarks

Functions
void	MPIB_bcast_timer_init (MPI_Comm comm, int parallel, MPIB_precision precision)
void	MPIB_measure_bcast (MPIB_Bcast bcast, MPI_Comm comm, int root, int M, int max_reps, MPIB_result *result)

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Detailed Description

This module provides operation-specific benchmarks.

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Function Documentation

void MPIB_bcast_timer_init	(	MPI_Comm	comm,
		int	parallel,
		MPIB_precision	precision
	)

Performs the p2p benchmark with empty message with given precision and sets up an internal global variable, which is used by MPIB_measure_bcast. Called by MPIB_measure_bcast. Can be called directly before measurements.

Attention:

As the global variable is an array, the memory should be freed by

 MPIB_bcast_timer_init(MPI_COMM_NULL, (MPIB_precision){0, 0, 0}) 

Parameters:

	comm	communicator
	parallel	several non-overlapped point-to-point communications at the same time if non-zero
	precision	measurement precision

void MPIB_measure_bcast	(	MPIB_Bcast	bcast,
		MPI_Comm	comm,
		int	root,
		int	M,
		int	max_reps,
		MPIB_result *	result
	)

Measures the execution time of bcast between root and the rest of processes. Based on . Reuses already obtained empty-roundtrip times if the previous initialization was performed on the same communicator. Otherwise, initializes the bcast timer by calling MPIB_bcast_timer_init.
In the loop over processes, except root:
In the loop over repetitions:

• bcast at all processes except root and current process in the loop
• bcast and empty recv at root and measures the execution time
• bcast and empty send at current process in the loop

Having substructed the half of empty-roundtrip times, finds maximum.
Broadcasts the result.

Note:

No double barriers as no need in synchronization.

No precision as we cannot interrupt the process of measurement by broadcasting the error value after each repetition.

Parameters:

	bcast	bcast implementation
	comm	communicator
	root	root process
	M	message size
	max_reps	maximum number of repetitions
	result	measurement result