understanding dynamic parallelism

Understanding Dynamic ParallelismKnow your code and know yourself

Presenter: Mark O’Connor, VP Product Management

Agenda

• Introduction and Background

• Fixing a Dynamic Parallelism Bug

• Understanding Dynamic Parallelism

• Questions & Answers

• Parallel development tools company since 2002

‒ Leading in HPC software tools market worldwide

‒ Global customer base

• Making parallel programming accessible to the widest range

of scientists and programmers

‒ Design an unrivaled productive and easy-to-use development environment…

‒ … To help you reach the highest level of performance and scalability

‒ Define a new standard of customer support

Allinea

The Company

• A modern integrated environment for HPC developers

• Supporting the lifecycle of application development

and improvement

‒ Allinea DDT : Productively debug code

‒ Allinea MAP : Enhance application performance

• Designed for productivity

‒ Consistent easy to use tools

‒ Enables effective HPC development

• Improve system usage

‒ Fewer failed jobs

‒ Higher application performance

Allinea Unified environment

Unified building blocks

in production since 2010

Shared Graphical Interface

Shared Scalable Architecture

Shared Configuration Files

Shared Intelligence and Data Consolidation

• Parallel profiler designed for:

‒ C/C++, Fortran

‒ Multiprocess code

Interdependent or independent processes

‒ Multithreaded code

Monitor the main threads for each process

‒ Accelerated codes

GPUs, Intel Xeon Phi

• Improve productivity :

‒ Helps you detect performance issues quickly and easily

‒ Tells you immediately where your time is spent in your source code

‒ Helps you to optimize your application efficiently

Allinea MAP

Increase application performance

• Look at the entire application on real data sets

– Visualize the entire run at full scale, not just reduced sets

– Zoom in to explore iterations, functions and loops

• Understand the nature of bottlenecks

– Source code viewer pinpoints bottleneck locations

– CPU, MPI and memory access metrics identify the cause

Allinea MAP

Find performance issues quickly

• Graphical debugger designed for:

‒ C/C++, Fortran, UPC, CUDA

‒ Multithreaded code

Single address space

‒ Multiprocess code

Interdependent or independent processes

‒ Accelerated codes

GPUs, Intel Xeon Phi

‒ Any mix of the above

• Slash your time to debug :

‒ Reproduces and triggers your bugs instantly

‒ Helps you easily understand where issues come from quickly

‒ Helps you to fix them as swiftly as possible

Allinea DDT

Fix software problems - fast

• Where did it happen?

‒ Allinea DDT leaps to source automatically

‒ Merges stacks from processes and threads

• How did it happen?

‒ Some faults evident instantly from source

• Why did it happen?

‒ Real-time data comparison and consolidation

‒ Unique “Smart Highlighting” – coloring

differences and changes

‒ Sparklines comparing data across processes

Allinea DDT

Scalable debugging by design

• Debugging logbook

‒ Records debugging activity

‒ Compare runs side-by-side

‒ Extends offline debugging capabilities

Benefit : Compare sane runs to buggy runs to quickly narrow down your problem.

New in Allinea DDT 4.1

Debug problems even quicker



• Version control integration

‒ Highlights where source code has been changed

‒ Source code annotated with a change heatmap

‒ Support for Mercurial, CVS, SVN, Git…

Benefit : Quickly identify the cause of regressions by seeing at a glance what has changed

• Visualization enhancements

‒ Pick cells and interact with them in the debugger –

e.g. set a watchpoint

‒ Display of multiple datasets

‒ Wizard to guide data layout

Benefit: Link visualization to precise memory areas to

shorten the debugging process


Tighten the link with VisIt

Leading the way to Innovation

• Support for accelerated environments– CUDA 5.0 and Kepler 20

– Intel Xeon Phi Coprocessor

– GPU directives (both OpenACC and non-OpenACC)

• Support for complex architectures

– Debug and profile MPI, OpenMP and CUDA combinations

– Supports low power CPU architectures (Moonshot program)

– Support for all major compilers, MPI and OpenMP implementations

• Quick resolution of our customer issues

– 90% of support tickets are resolved within 7 days

Murex : NVIDIA Carma Dev Kit

University of Gent

Today: Debugging Dynamic Parallelism on K20

Debugging Dynamic Parallelism


wait, what?

Debugging is About Understanding

Which values are put into data and when?

What's the relationship between n and data?

How many kernels are launched?

What actually

happens here?

Allinea DDT + MAP

See which loops can be offloaded

to the GPU most effectively

with Allinea MAP

Get correct results fast using the

industry-leading parallel debugger

Full support for NVIDIA CUDA 5

An integrated, ready-to-run development suite

Questions and Answers

Mark O’Connor, VP Product Management

Robert Rick, VP Sales, Director of Operations, Americas

Upcoming GTC Express Webinars

July 10

Introduction to the CUDA Toolkit as an Application Build Tool

Adam DeConinck, HPC Systems Engineer, NVIDIA

July 11

Uncovering the Elusive HIV Capsid with Kepler GPUs

Juan R. Perilla, Postdoctoral Fellow, University of Illinois at

Urbana-Champaign

Register at www.gputechconf.com/gtcexpress

understanding dynamic parallelism

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