Cluster Postmark with MPI-IO and PLFS support

Introduction

Renaud Lachaize and Michail Flouris have modified the well-known Postmark v1.5 filesystem benchmark to run on a cluster using MPI, in order to measure cluster/parallel filesystem performance. However it only supports POSIX file API which is not the only option in HPC. So I extended the tool to support MPI-IO and PLFS IO interface so that we can measure the IO performance for different IO interfaces.

PLFS is a checkpoint filesystem for parallel applications.

Dependence and Install Instructions

Dependence

• MPI
• PLFS

Install Instruction

cd /path/to/source/
make

Configuration and Execution

It is mostly the same as Postmark, and for the users who are not familiar with Postmark, please refer to the first document in references <<PostMark: A New File System Benchmark>>. There is an example of configure file in the source tree. Here is a brief introduction to the commands:

set size - Sets low and high bounds of files
set number - Sets number of simultaneous files
set seed - Sets seed for random number generator
set transactions - Sets number of transactions
set location - Sets location of working files
set read - Sets read block size
set write - Sets write block size
set buffering - Sets usage of buffered I/O
set bias read - Sets the chance of choosing read over append
set bias create - Sets the chance of choosing create over delete
run - Runs one iteration of benchmark
show - Displays current configuration
help - Prints out available commands
quit - Exit program

You should pay attention to three command lines in the configuration file for postmark:

• set iointerface POSIX (It means that POSIX file functions will be used to do IOs. You could also choose LIBC, PLFS or MPI) NOTE: This MUST appear in the first line.
• set partition prefix (It means every process will create files with its rank number as prefix, for example, rank 0 will create files as r0-xxxx and rank 1 creates r1-xxxx. The other possible value is “subdir” which means that every process creates a sub directory such as Rank-0, Rank-1 and creates all its test files in it.)
• set report cluster (It means that rank 0 will collect all timing information from all of the processes and print the aggregated result out.) Other commands have just the same meaning as the original postmark.

You could run the benchmark using the following command:

mpirun -np N ./postmark ./simple.conf

Results

Only the transaction per second is meaningful, others are misleading.

References

• PostMark: A New File System Benchmark
• Parallel Postmark Benchmark
• PLFS: A Checkpoint Filesystem for Parallel Applications