S. Boeriu1 and J. C. Bruch, Jr. 2 1Center for Computational Science and Engineering

The VAMPIR and PARAVER performance analysis tools applied to a wet chemical etching parallel algorithm

• S. Boeriu1 and J.C. Bruch, Jr.2

• 1Center for Computational Science and Engineering

• 2Department of Mechanical and Environmental Engineering

• and Department of Mathematics

• University of California, Santa Barbara

• http://www.engineering.ucsb.edu/~hpscicom

Acknowledgements

Outline of Presentation

Outline of Presentation

• 1. Introduction (Physical problem)

Outline of Presentation

• 1. Introduction (Physical problem)

Outline of Presentation

• 1. Introduction (Physical problem)

Outline of Presentation

• 1. Introduction (Physical problem)

Outline of Presentation

• 1. Introduction (Physical problem)

Outline of Presentation

• 1. Introduction (Physical problem)

Outline of Presentation

• 1. Introduction (Physical problem)

Outline of Presentation

• 1. Introduction (Physical problem)

Physical problem

Simplifying assumptions

Simplifying assumptions

• i. There is no convection in the etching medium

Simplifying assumptions

• i. There is no convection in the etching medium

Simplifying assumptions

• i. There is no convection in the etching medium

Simplifying assumptions

• i. There is no convection in the etching medium

Problem formulation

Fixed domain formulation

Numerical Algorithm

Numerical algorithm (cont.)

Test case

Domain decomposition

Load balancing information for the test case

Performance tools and considerations

• The parallel program is monitored while

• it is executed. Monitoring produces

• performance data that is interpreted in

• order to reveal areas of poor performance.

• The program is then altered and the

• process is repeated until an acceptable

• level of performance is reached.

VAMPIR (Visualization and Analysis of MPI Resources – 2.0)

• VAMPIR 2.0 is a post-mortem trace visualization tool from Pallas GmbH

• http://www.pallas.com

• It uses the profile extensions to MPI and

• permits analysis of the message events where

• data is transmitted between processors during

• execution of a parallel program. It has a

• convenient user-interface and an excellent

• zooming and filtering. Global displays show all

• selected processes.

PARAVER(Parallel Program Visualization and Analysis Tool)

• PARAVER is a flexible parallel program visualization and analysis tool based on an easy-to-use Motif GUI (graphical user interface)

• PARAVER was developed to respond to the

• basic need to have a qualitative perception of the

• application behavior by visual inspection and then

• to be able to focus on the detailed quantitative

• analysis of the problems.

Paraver (Parallel Program Visualization and Analysis Tool)

• Powerful flexible parallel program visualization tool based on an easy-to-use Motif GUI (graphical user interface)

• Developed by :

• European Center for Parallelism of Barcelona (CEPBA)

• Universitat Politecnica de Catalunya

• http://www.cepba.upc.es/

Paraver is designed to visualize and analyze

• Paraver is designed to visualize and analyze

• - Communication and load balance

• - Combining OpenMP and MPI

• - Hardware performance and counters

• Usage

• - Compile programs with special libraries

• - Run programs to produce trace files

• - View and analyze traces

• - Designed to help in program understanding and optimization

Inefficient programming example

Inefficient programming example

• Load imbalance (inefficient memory use)

Inefficient programming example

• Load imbalance (inefficient memory use)

Inefficient programming example

• Load imbalance (inefficient memory use)

Load imbalance - VAMPIR

Load imbalance - PARAVER

The memory hierarchy

Array Allocation

Example of coding

• c-

• c- calculate error in the top region and update u1old

• do 370 i = iam*numrows1 + 1,lastrow

• do 380 j = 2,maxcol1

• if (abs(u1new(i,j) - u1old(i,j)).gt.err) then

• err = abs(u1new(i,j) - u1old(i,j))

• endif

• u1old(i,j) = u1new(i,j)

• 380 continue

• 370 continue

• c-

Load balance - VAMPIR

Load balance - PARAVER

Conclusions

• A significant factor that affects the performance of a parallel application is the balance between communication and workload. The challenge of the message passing model is in reducing message traffic over the interconnection network. To fully understand the

• performance behavior of such applications, analysis and

• visualization tools are needed. Two such tools, VAMPIR

• and PARAVER, were used to analyze the performance of

• the etching application. It was seen that optimization of

• the parallel code can be carried out in an iterative process

• involving these tools to investigate performance issues.

Web Sites

• Project site

• http://www.engineering.ucsb.edu/~hpscicom

• San Diego Supercomputer Center

• http://www.npaci.edu/Horizon/guide_linked/bh_tools_txt.html

• VAMPIR

• http://www.pallas.com

• PARAVER

• http://www.cepba.upc.es/