Q-Logic IB6054601-00 D Manuel D’Utilisation

A – Benchmark Programs
Benchmark 3: Messaging Rate Microbenchmarks

A-4

IB6054601-00 D

Q

benchmark (as shown in the example above). It has been enhanced with the 
following additional functionality:

■

Messaging rate reported as well as bandwidth

■

N/2 dynamically calculated at end of run

■

Allows user to run multiple processes per node and see aggregate bandwidth 
and messaging rates

The benchmark has been updated with code to dynamically determine which 
processes are on which host. This is an example showing the type of output you 
will see when you run 

mpi_multibw

:

$ mpirun -np 8 ./mpi_multibw

This will run on four processes per node. Typical output might look like:

# PathScale Modified OSU MPI Bandwidth Test

(OSU Version 2.2, PathScale $Revision: 1.1 $)

# Running on 4 procs per node

# Size 

  Aggregate Bandwidth    (MB/s) Messages/s

1   

8.150462   

8150461.697283

2  

16.693747  

8346873.631841

4  

33.086567  

8271641.814960

8  

66.733488  

8341686.016159

16  

108.097082 

6756067.602089

32  

213.733132  

6679160.388156

64  

389.544112  

6086626.744516

128 569.671531 

 

4450558.832794

256  

725.826904  

2835261.345093

512  

839.450014  

1639550.807757

1024  

913.428063  

892019.592596

2048  

954.482747  

466056.028717

4096  

954.474461  

233025.991467

8192  

954.452712  

116510.340772

16384  

954.496729  

58257.857017

32768  

954.547225  

29130.469523

65536  

949.074433  

14481.726572

131072  

951.786548 

7261.555084

262144 952.193849 

 

3632.331272

524288  

952.391830  

1816.543255

1048576  

952.490368  

908.365600

2097152  

952.539382 

454.206172

4194304  

952.566591  

227.109573

Searching for N/2 bandwidth. Maximum Bandwidth of 954.547225 

MB/s...

Found N/2 bandwidth of 476.993060 MB/s at size 94 bytes

This microbenchmark is available and can be downloaded from the QLogic website: