Apple's Grand Central Dispatch: Path to Multicore
Apple has taken multicore to heart with Grand Central Dispatch, a deeply ingrained capability of their Snow Leopard OS to really help with using multicore parallelism. I'm a big fan, including the fact that it is not all new.
There are many sessions at WWDC (Apple's developer conference) which promise to be quite informative. Apple is really helping unlock the power of multicore processors.
What Is It?
At the heart of Grand Central Dispatch is NSOperationQueue which debuted in "Leopard" (released October 2007). Around this simple "hey, throw this work on the queue" is a commitment in the operating systems and tools to encourage its use and make it easy to access.
On Friday of this week, after attending sessions this week from Apple on Grand Central Dispatch at WWDC, I recommend not missing a session which show Grand Central Dispatch in action and comparing it with the same program using TBB.
WWDC Session 131: Scaling Performance Using Grand Central Dispatch and Intel Libraries, Friday 2:00-3:15 pm
Session 131 Abstract: Scaling the performance of your application to get the most out of a multicore Mac requires an understanding of the various tools and libraries available at your disposal. Intel engineers will demonstrate, with the help of a real-world use case, how you can employ Apple's Grand Central Dispatch, Intel's Threading Building Blocks and Intel's Performance Primitives to achieve and scalable application performance on Mac OS X.Intel Presenters: Pallavi Mehrotra, Richard Hubbard
Pallavi and Richard have a very education talk that will make you wanting to learn even more!
Will GCD replace TBB?
No, because that's not what it's about. In fact, it may be worth porting TBB on top of GCD one day. We'll see what the TBB open source project decides. GCD is an enabling technology for applications and tools. An application can use GCD directly with great affect. Pallavi and Richard show that in their talk.A Simple Answer?
I'd use GCD when programming in Objective-C, or TBB when programming in C++ or C. Session 131 shows that either choice can work well on Mac OS X.A Little Deeper Answer?
TBB has more knobs, is cross-OS portable, and addresses issue specific to C++.
GCD has deep support from Apple in tools and Mac OS X, and has been well integrated into Objective-C. I'm sure this will make a fertile ground for more blogging in the future. This week, it's time to learn at WWDC.
This Week's Multicore Reading List
MATLAB and Google App Engine
Logging In C++ : Part 2
Improving log granularityA Conversation with BitMagic's Developer
Prefer Structured Lifetimes: Local, Nested, Bounded, Deterministic
- Intel Parallel Studio; Download the free eval today!
- Parallelism Breakthrough Video Series; Watch and learn more about Intel® Parallel Studio
- 2009 Intel Software Webinar Series; View On-Demand webinars
- Coding for Multi-core Processes; Intel® Compiler Pro eBook
- Performance Through Parallelism; Intel® Tuning for Vista eBook
- Intel® Software Network; Connect with developers and Intel engineers
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November 17, 2009
Visual Effects for Animation - presented by DreamWorks Animation
Speaker: Ron Henderson (Bio)Ron Henderson manages the FX Tools group at DreamWorks Animation, where he is responsible for developing physical simulation and procedural modeling tools. These systems have been used for key visual effects in recent films such as Kung Fu Panda and Monsters vs. Aliens (March 2009).
Prior to joining DreamWorks in 2002 he was a senior scientist at Caltech with a joint appointment to the Applied Math and Aeronautics departments, where he worked on efficient techniques for the direct numerical simulation of fluid turbulence.Abstract:
In this webinar, Ron Henderson will show examples of visual effects, from hair and feathers to smoke and fire, from a variety of DreamWorks Animation feature films. He will discuss in general terms the kinds of techniques used to achieve particular visual effects. Finally, Henderson will show a detailed breakdown of the dam-breaking scene from Madagascar: Escape 2 Africa, demonstrating how different elements of key frame animation, simulation, and rendering are combined in a real production shot. -
December 1, 2009
A Quick and Easy Way to Parallelize a Legacy Codebase with Intel® Threading Building Blocks (TBBs)
Speaker: Bernard Laberge, Avid, Senior Principal Engineer (Bio)Bernard Laberge is a senior principal engineer in the video editors division at Avid. During his seven years with the company he has been actively involved in the replacement of the legacy video processing engines used by Avid editors with a common hardware-abstracted, component-based video processing engine currently running on the CPU with SIMD optimized code, GPU, and dedicated hardware.
Abstract:
Learn how to overcome the limitations of a thread-based scheduler, including dealing with the absence of recursive parallelism support and the inefficient handling of unbalanced processing load. Bernard Laberge addresses how Avid resolved the expensive refactoring of their thread-based scheduler into a task-based solution by choosing Intel® Threading Building Blocks (TBBs). He explores how Avid was able to easily integrate the Intel TBBs into their video editor applications and more than 5 million lines of code. -
December 15, 2009
How to Use Intel® Parallel Studio to Streamline Code Development in a Multicore Environment
Speaker: Matt Dunbar, Director for Performance Technology, SIMULIA (Bio)Matt Dunbar is the director for performance technology at SIMULIA. Since joining the company in 1993, he has worked on parallelization of the Abaqus suite of products, initially for shared memory architectures and more recently for distributed memory architectures. Dunbar has also been intimately involved in selecting both the hardware and software tools used in the development of the Abaqus product line.
Abstract:
Resolve elusive, costly multithreading errors quickly and efficiently with Intel® Parallel Studio. While many coding problems that lead to bugs in software applications are typically straightforward logic errors, errors in managing memory and in multithreading code can sometimes take weeks to months to diagnose and fix. Matt Dunbar explores how and why taking advantage of multicore processors through multithreaded code is critical for compute-intensive applications. While spotlighting his work on SIMULIA's Abaqus finite element solver, Dunbar addresses the need for multicore execution and shares his experiences using Intel Parallel Studio to streamline code development in a multicore environment.



