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# Difference between revisions of "Vampirtrace"

The VampirTrace library allows MPI communication events of a parallel program to be recorded as a trace file. Additionally, certain program-specific events can also be included. To record MPI communication events, simply relink the program with the VampirTrace library. A new compilation of the program source code is only necessary if program-specific events should be added.
 Developer: ZIH TU Dresden and JSC/FZ Juelich Platforms: NEC Nehalem Cluster Category: Performance Analyzer License: BSD License Website: VampirTrace homepage

## Introduction

Tracing an application with Vampir is done in three steps:

1. Compiling with the vampirtrace wrappercompiler
2. Running the application
3. Analysing the trace files using vampir or vampir-server

For detailed usage of Vampirtrace see the user manual which can either be found on your local machine or in the internet.

## Usage

### Compiling with the vampirtrace wrappercompiler

First load the needed software module:

Now you can compile your application using the wrapper compilers vtcc, vtc++ or vtf90 as described in the user VampirTrace manual.

Note: When using vampirtrace in combination with MPI you will need at least to specify the name of your mpi compiler to VampirTrace
vtf90 -vt:f90 mpif90
vtcc  -vt:cc  mpicc
vtcxx -vt:cxx mpicxx


### Generating the trace files

Run your applicatin as usual. This will generate the needed tracefiles

#### BW-Grid special:

On the BW-Grid you first have to login to a node as some libs are not accessible from the frontend

qsub -I -l walltime=1:00:00

### Viewing traces with vampir or Vampir-Server

There are two GUIs available to view your trace files: Vampir and Vampir-Server. For both you will need read access to all generated output files (*.def.z, *.events.z, *.otf).

Note: Because Vampir and Vampir-Server are GUIs don't forget to use X-forwarding when you login via ssh.

#### Vampir

Vampir is the sequential version of the graphical trace file analyzing software. It is capable of analyzing smaller trace files and should not be used for files which have 100MB or more.

#### Vampir-Server

Vampir-Server is the parallel version of the graphical trace file analyzing software. It can be found on the SX-8 frontend (a1.hww.de). The tool consists of a client and a server. The server itself is a parallel MPI Program.

First load the necessary software module

Now start the server and afterwards the client

on laki:

mpirun -np 4 vngd &

on hermit:

aprun -n 4 vngd &

Remember the port number which will be displays as you will need it later on. Then start the graphical client

vng

The last step is to connect the client to the server using the port number offered you from the server. This is done under

file $\rightarrow$ Connect to Server ...


Then you can open your traces via

file $\rightarrow$ Open Tracefile  ...


Select the desired *.otf file

## Trouble shooting

#### Incomplete trace files

[0]VampirTrace: Maximum number of buffer flushes reached (VT_MAX_FLUSHES=1)
[0]VampirTrace: Tracing switched off permanently


Trace data did not fit into a single VampirTrace buffer. Unlimit the number of buffer reuses with

export VT_MAX_FLUSHES=0

#### Not enough space on /tmp

[0]VampirTrace: FATAL: OTF_WStream_writeLeave failed:
ERROR in function OTF_WBuffer_writeUint64, ...
OTF_WBuffer_guarantee() failed.


Check if /tmp has filled up to 100% by executing

df -h | grep /tmp

A solution is to use a workspace in combination with the VT_PROFM_LDIR variable:

export VT_PROFM_LDIR=\$(ws_allocate vt_trace_tmp 5)

#### Library issues on NEC

Try to export LD_LIBRARY_PATH

export LD_LIBRARY_PATH=/opt/NECcomp/compiler100/ia64/lib