Q-Logic IB6054601-00 D Manuel D’Utilisation

3 – Using InfiniPath MPI

InfiniPath MPI Limitations

IB6054601-00 D

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Q

Symbolic debugging is easier than machine language debugging. To enable 
symbolic debugging you must have compiled with the 

-g

 option to 

mpicc 

so that 

the compiler will have included symbol tables in the compiled object code.

To run your MPI program with a debugger use the 

-debug 

or 

-debug-no-pause

 

and 

-debugger

 options to 

mpirun

. See the 

man

 pages to 

pathdb

, 

gdb

, and 

strace

 

for details. When you run under a debugger, you get an xterm window on the front 
end machine for each node process. Thus, you can control the different node 
processes as desired.

To use 

strace

 with your MPI program, the syntax would be:

$ mpirun -np n -m mpihosts strace program-name

The following features of InfiniPath MPI especially facilitate debugging:

■

Stack backtraces are provided for programs that crash.

■

-debug

 and 

-debug-no-pause

 options are provided for 

mpirun

 that can make 

each node program start with debugging enabled. The 

-debug

 option allows you 

to set breakpoints, and start running programs individually. The 

-debug-no-pause

 option allows postmortem inspection. Note that you should 

set 

-q 0

 when using

 -debug.

■

Communication between 

mpirun

 and node programs can be printed by 

specifying the 

mpirun -verbose

 option.   

■

MPI implementation debug messages can be printed by specifying the 

mpirun 

-psc-debug-level 

option. Note that this can substantially impact the 

performance of the node program.

■

Support is provided for progress timeout specifications, deadlock detection, and 
generating information about where a program is stuck. 

■

Several misconfigurations (such as mixed use of 32-bit/64-bit executables) are 
detected by the runtime.

■

A formatted list containing information useful for high-level MPI application 
profiling is provided by using the 

-print-stats

 option with 

mpirun

. Statistics 

include minimum, maximum and median values for message transmission 
protocols as well as a more detailed information for expected and unexpected 
message reception. See 

 for more information and a sample 

output listing.

The current version of InfiniPath MPI has the following limitations:

By default, at most eight node programs per node with the QHT7140 are allowed, 
and at most four node programs per node with the QLE7140. The error message 
when this limit is exceeded is: