BenchIO Benchmarking Application

Description

The BenchIO benchmark application measures the speed at which large amounts of data (e.g. for checkpointing) can be written using different IO methods. Note that IO is highly dependent on the IO parameters chosen and the file system and networks of the particular machine.

At the moment this Benchmark contains parameter files for checkpointing 100 3-dimensional grid functions in different ways. These grid functions are all given the local size on each processor of 80-cubed, and use REAL*8 data types, so that each processor needs to write a total of 400,000 KiloBytes is contributed to the checkpoint file from each processor.

Factors which will influence how quickly the checkpoint file is written include:

• The filesystem written to on a particular machine
• The network connection to that filesystem
• The choice of Cactus parameters used to write the checkpoint file, for example parameter files are included for
• Writing a single file (all data goes through processor 0)
• Each processor writing its own data (one file per processor)
• Each n-th processor collecting data from the next (n-1) processors and writing to file
• The data format used for writing, parameter files are included for HDF5 and FlexIO