EPCC I/O benchmarking applications
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README.md

README.md

benchio

EPCC I/O benchmarking application. Tests write bandwidth to a single shared file for a given problem size per processor (weak scaling).

Each test is performed 10 times and the minimum, maximum and average bandwidth returned. It is recommended that the maximum bandwidth be considered in most cases, due to variations in I/O performance from user contention.

Data layout is 3D strided - intended to more closely resemble that of a real world application than 2D sequential. By default, array size is 256x256x256.

Supports POSIX (serial), MPI-IO, HDF5 and NetCDF backends. A run will test all backends included at compile time.

Compilation

Tested under all three programming environments on ARCHER: Cray, GNU, and Intel.

For an ARCHER build:

module load cray-netcdf-hdf5parallel/4.4.0

module load cray-hdf5-parallel/1.8.16

make clean

make

For other platforms, edit the Makefile to point variables FC and CC to MPI compilers (e.g. mpif90 and mpicc), and edit LFLAGS to the location of HDF5 and NetCDF libraries. Then make clean && make.

Building with selected backends

POSIX (serial), MPI-IO, HDF5 and NetCDF backends can be disabled by commenting out the relevant FFLAGS lines in the Makefile. e.g. Commenting out: FFLAGS+= -DWITH_NETCDF will build the application with only MPI-IO and HDF5 support.

Running

For example, to test performance with maximum striping on Lustre:

mkdir -p benchio_files

lfs setstripe -c -1 benchio_files

aprun -n <NUMBER_OF_PROCESSORS> ./benchio.x

Explanation of commands follows:

The application expects a working directory with subdirectory benchio_files. An I/O error will be thrown if this subdirectory is not present.

Under Lustre, the appropriate striping patterns should be set on this subdirectory using the lfs setstripe command.

The benchio.x executable should be launched with the platform job launcher, e.g. aprun or mpirun. Results are written to STDOUT.

Complete sample run scripts are included in source/run_scripts.

Adjusting volume of data

The array size (per MPI rank) is controlled through the following constants in benchio.F90:

integer, parameter :: n1 = 256

integer, parameter :: n2 = 256

integer, parameter :: n3 = 256