|By J. Stan Cox, Bob Blainey, Vijay Saraswat||
|August 27, 2007 04:30 PM EDT||
As software developers we have enjoyed a long trend of consistent performance improvement from processor technology. In fact, for the last 20 years processor performance has consistently doubled about every two years or so. What would happen in a world where these performance improvements suddenly slowed dramatically or even stopped? Could we continue to build bigger and heavier, feature-rich software? Would it be time to pack up our compilers and go home?
The truth is, single threaded performance improvement is likely to see a significant slowdown over the next one to three years. In some cases, single-thread performance may even drop. The long and sustained climb will slow dramatically. We call the cause behind this trend the CLIP level.
- C - Clock frequency increases have hit a thermal wall
- L - Latency of processor-to-memory requests continues as a key performance bottleneck
- IP - Instruction-level Parallelism is already fully exploited by current processor and compiler technologies.
This article will dive deeper into the current issues challenging processor performance improvement and include a high-level overview of the key microprocessor players: Intel, AMD, Sun, and IBM. Finally, we'll take a deep dive into the challenges, opportunities, and technologies available to Java programmers to take advantage of concurrent programming to leverage these new processor technologies. If you're not programming in parallel today, you will be soon.
Increases in processor clock frequency are slowing and in many cases are being decreased to reduce power consumption. One trend continues though. The industry continues to shrink the size of transistors, doubling the number of transistors on a chip about every two years or so. In 2007 most major chip manufacturers will begin the shift from a 60nm to a 45nm process. This will yield transistors about 1/2000th the width of a human hair! To provide a relative perspective, a silicon atom itself is about 1/4nm. Obviously continuing to halve the size of transistors will also reach a limit in the not too distant future. But that's a topic for another paper.
So, how will the industry use this new transistor budget to improve processor performance? Techniques such as superscalar execution, pipelining, and speculative processing with branch prediction have added significant complexity to microprocessor designs, but have also been successful at improving performance. Unfortunately, the latency to memory on cache misses and the high frequency of branches in most workloads is proving to be a limiting factor. Building ever-larger caches is one way to mitigate the memory latency problem but as cache size exceeds common working set size, there are rapidly diminishing returns for investing transistors in cache memory.
Instead, the industry is moving toward multi-core, multithreading, and specialization. Instead of improving the performance of a single thread on a single core, the transistor budget is being used to add multiple cores to a single chip. Further, in many cases each core is capable of running multiple threads to hide memory latency. When one thread is blocked by a long latency event, such as a cache miss, the processor simply switches to another thread to execute. Also, many chip designs now include special-purpose processing units that make effective use of transistors for specific tasks such as cryptography.
Taking a closer look at the processors themselves, the IBM Power is distinguished as being the first to introduce multiple cores on a chip in the Power 4 design in 2001. IBM recently introduced the Power 6 processor, which combines two high-performance cores on a chip with each core supporting two-way multithreading. Besides providing multiple cores, the Power 6 also achieved an amazing 4.7GHz clock rate showing that IBM remains serious about single-thread performance while keeping pace with the industry on multi-core. As Power 6 is destined to be included in high-end servers, IBM has also focused heavily on RAS (reliability, availability, serviceability) and virtualization.
In the x86 architecture camp, rivals AMD and Intel have both recently introduced multi-core processors. In 2006, Intel introduced chips with two cores while chips with four cores, based on 45nm technology, shouldappear this year. As part of the move to multi-core, Intel removed support for its version of multithreading known as "hyperthreading," although multithreading is expected to return in future designs. Not to be outdone, AMD later this year, will introduce its first four-core chip known as Barcelona. Both Intel and AMD continue to focus on single-thread performance as well, each introducing new innovations in instruction-level parallelism and caches. One key difference in their designs is the memory bus architecture. Intel is continuing with its symmetric front-side bus architecture. AMD, on the other hand, has introduced a NUMA-based design based on the open Hypertransport technology in hopes of alleviating the memory bus bottleneck.
Sun has adopted a more radical departure in design from prior generations of SPARC. At the end of 2005, Sun released the UltraSPARC T1 or Niagara processor. Niagara includes up to eight cores, significantly more than competing server processors. Sun was able to squeeze eight cores on the chip by shifting focus away from the best achievable single-thread performance toward high chip-level throughput. Niagara cores run at a relatively low clock rate and don't support out-of-order processing, branch prediction, or many other common ILP optimizations. Instead they depend on four-way multithreading to tolerate long waits for memory. The goal is to achieve high overall throughput through application concurrency. However, applications with lower concurrency may run significantly slower on Niagara relative to the other processors described here.
At this point, all of the key players are producing chips with multiple cores but diverging in core design, memory nest, and other important aspects. The key to success for processor designers over the next few years will be in the innovative use of their transistor budget. Architects will make strategic tradeoffs between single-thread performance, massive concurrency, cache sizes, power consumption, and specialized processing units. The companies that make tradeoffs in the most innovative ways to meet the demands of the market should emerge as the winners.
As a developer, it will be important for you to learn the skills necessary to develop applications that can run with high performance on these increasingly parallel processors. Since single-thread performance isn't likely to improve at historical rates, the developer will have to look to concurrency to improve performance for a given task. The goal of parallel programming is to reduce the time of a task by dividing it into a set of subtasks that can be processed concurrently. While this may seem simple enough, experience shows that developing correct and effective parallel programs is surprisingly difficult. To utilize parallelism in hardware effectively, software tasks must be decomposed into subtasks, code must be written to coordinate the subtasks and work must be balanced as much as possible. Still sound easy? Read on.
As you get started with parallel programming, the first rule to become familiar with is Amdahl's Law. Amdahl's Law says that speeding up your program is limited by the part that's not running in parallel. For example, if a profile reveals that 20% of the time is spent in code that can only run sequentially on one processor, then the best speed increase you can possibly get, even with perfect parallelization of the rest of your program is 5x, no matter how many processors you throw at it. Load imbalance is a similar problem. If you've divided your code into N subtasks, the time taken to execute them is not 1/N. Rather the time taken is the maximum of the execution times of the subtasks.
If getting your code divided into subtasks and ensuring that work is well balanced sounded hard, then let us introduce you to the coordination problem. Unfortunately, very few programs can be parallelized so simply. The reason is that those subtasks are likely to want to operate on the same data and some of the subtasks may have to wait for others to do their thing before proceeding. It's okay if two subtasks want to read the same memory location in parallel, but if one of them wants to write to the location, you've got trouble because you can't predict which subtask will get to it first.
For example, operations to insert and remove objects from a linked list must be executed so that updates to the data structures happen sequentially and don't corrupt each other. An incorrect ordering of accesses to a memory location is called a data race and it can be one of the most difficult bugs to find because your code might behave differently on each run and might even change once you decide to start debugging. To deal with this problem, most programming environments include mechanisms to ensure that a subtask has exclusive access to specific memory, commonly called locks. Unfortunately locks bring their own unique problems when multiple subtasks compete for access and, if used indiscriminately, can reverse all of your hard work in parallelizing your code by making subtasks wait too often or too long for exclusive access to shared memory.
|Jim Falgout 11/26/07 09:37:55 AM EST|
The X10 site does not seem very active. The news feed on the last release is dated December of 2006. Do you have any information on the current state of X10?
Countless business models have spawned from the IaaS industry – resell Web hosting, blogs, public cloud, and on and on. With the overwhelming amount of tools available to us, it's sometimes easy to overlook that many of them are just new skins of resources we've had for a long time. In his general session at 17th Cloud Expo, Harold Hannon, Sr. Software Architect at SoftLayer, an IBM Company, broke down what we have to work with, discussed the benefits and pitfalls and how we can best use them to design hosted applications.
Nov. 30, 2015 03:45 PM EST
Most of the IoT Gateway scenarios involve collecting data from machines/processing and pushing data upstream to cloud for further analytics. The gateway hardware varies from Raspberry Pi to Industrial PCs. The document states the process of allowing deploying polyglot data pipelining software with the clear notion of supporting immutability. In his session at @ThingsExpo, Shashank Jain, a development architect for SAP Labs, discussed the objective, which is to automate the IoT deployment process from development to production scenarios using Docker containers.
Nov. 30, 2015 03:30 PM EST
We all know that data growth is exploding and storage budgets are shrinking. Instead of showing you charts on about how much data there is, in his General Session at 17th Cloud Expo, Scott Cleland, Senior Director of Product Marketing at HGST, showed how to capture all of your data in one place. After you have your data under control, you can then analyze it in one place, saving time and resources.
Nov. 30, 2015 03:15 PM EST Reads: 242
The Internet of Things (IoT) is growing rapidly by extending current technologies, products and networks. By 2020, Cisco estimates there will be 50 billion connected devices. Gartner has forecast revenues of over $300 billion, just to IoT suppliers. Now is the time to figure out how you’ll make money – not just create innovative products. With hundreds of new products and companies jumping into the IoT fray every month, there’s no shortage of innovation. Despite this, McKinsey/VisionMobile data shows "less than 10 percent of IoT developers are making enough to support a reasonably sized team....
Nov. 30, 2015 03:00 PM EST Reads: 492
Just over a week ago I received a long and loud sustained applause for a presentation I delivered at this year’s Cloud Expo in Santa Clara. I was extremely pleased with the turnout and had some very good conversations with many of the attendees. Over the next few days I had many more meaningful conversations and was not only happy with the results but also learned a few new things. Here is everything I learned in those three days distilled into three short points.
Nov. 30, 2015 02:00 PM EST Reads: 366
DevOps is about increasing efficiency, but nothing is more inefficient than building the same application twice. However, this is a routine occurrence with enterprise applications that need both a rich desktop web interface and strong mobile support. With recent technological advances from Isomorphic Software and others, rich desktop and tuned mobile experiences can now be created with a single codebase – without compromising functionality, performance or usability. In his session at DevOps Summit, Charles Kendrick, CTO and Chief Architect at Isomorphic Software, demonstrated examples of com...
Nov. 30, 2015 01:45 PM EST Reads: 430
As organizations realize the scope of the Internet of Things, gaining key insights from Big Data, through the use of advanced analytics, becomes crucial. However, IoT also creates the need for petabyte scale storage of data from millions of devices. A new type of Storage is required which seamlessly integrates robust data analytics with massive scale. These storage systems will act as “smart systems” provide in-place analytics that speed discovery and enable businesses to quickly derive meaningful and actionable insights. In his session at @ThingsExpo, Paul Turner, Chief Marketing Officer at...
Nov. 30, 2015 01:45 PM EST Reads: 434
In his keynote at @ThingsExpo, Chris Matthieu, Director of IoT Engineering at Citrix and co-founder and CTO of Octoblu, focused on building an IoT platform and company. He provided a behind-the-scenes look at Octoblu’s platform, business, and pivots along the way (including the Citrix acquisition of Octoblu).
Nov. 30, 2015 01:00 PM EST Reads: 537
In his General Session at 17th Cloud Expo, Bruce Swann, Senior Product Marketing Manager for Adobe Campaign, explored the key ingredients of cross-channel marketing in a digital world. Learn how the Adobe Marketing Cloud can help marketers embrace opportunities for personalized, relevant and real-time customer engagement across offline (direct mail, point of sale, call center) and digital (email, website, SMS, mobile apps, social networks, connected objects).
Nov. 30, 2015 12:45 PM EST Reads: 342
The Internet of Everything is re-shaping technology trends–moving away from “request/response” architecture to an “always-on” Streaming Web where data is in constant motion and secure, reliable communication is an absolute necessity. As more and more THINGS go online, the challenges that developers will need to address will only increase exponentially. In his session at @ThingsExpo, Todd Greene, Founder & CEO of PubNub, exploreed the current state of IoT connectivity and review key trends and technology requirements that will drive the Internet of Things from hype to reality.
Nov. 30, 2015 10:45 AM EST Reads: 462
Two weeks ago (November 3-5), I attended the Cloud Expo Silicon Valley as a speaker, where I presented on the security and privacy due diligence requirements for cloud solutions. Cloud security is a topical issue for every CIO, CISO, and technology buyer. Decision-makers are always looking for insights on how to mitigate the security risks of implementing and using cloud solutions. Based on the presentation topics covered at the conference, as well as the general discussions heard between sessions, I wanted to share some of my observations on emerging trends. As cyber security serves as a fou...
Nov. 30, 2015 10:30 AM EST Reads: 354
With all the incredible momentum behind the Internet of Things (IoT) industry, it is easy to forget that not a single CEO wakes up and wonders if “my IoT is broken.” What they wonder is if they are making the right decisions to do all they can to increase revenue, decrease costs, and improve customer experience – effectively the same challenges they have always had in growing their business. The exciting thing about the IoT industry is now these decisions can be better, faster, and smarter. Now all corporate assets – people, objects, and spaces – can share information about themselves and thei...
Nov. 30, 2015 10:00 AM EST Reads: 292
The cloud. Like a comic book superhero, there seems to be no problem it can’t fix or cost it can’t slash. Yet making the transition is not always easy and production environments are still largely on premise. Taking some practical and sensible steps to reduce risk can also help provide a basis for a successful cloud transition. A plethora of surveys from the likes of IDG and Gartner show that more than 70 percent of enterprises have deployed at least one or more cloud application or workload. Yet a closer inspection at the data reveals less than half of these cloud projects involve production...
Nov. 30, 2015 09:00 AM EST Reads: 506
Discussions of cloud computing have evolved in recent years from a focus on specific types of cloud, to a world of hybrid cloud, and to a world dominated by the APIs that make today's multi-cloud environments and hybrid clouds possible. In this Power Panel at 17th Cloud Expo, moderated by Conference Chair Roger Strukhoff, panelists addressed the importance of customers being able to use the specific technologies they need, through environments and ecosystems that expose their APIs to make true change and transformation possible.
Nov. 30, 2015 08:00 AM EST Reads: 565
Microservices are a very exciting architectural approach that many organizations are looking to as a way to accelerate innovation. Microservices promise to allow teams to move away from monolithic "ball of mud" systems, but the reality is that, in the vast majority of organizations, different projects and technologies will continue to be developed at different speeds. How to handle the dependencies between these disparate systems with different iteration cycles? Consider the "canoncial problem" in this scenario: microservice A (releases daily) depends on a couple of additions to backend B (re...
Nov. 30, 2015 07:00 AM EST Reads: 470
Too often with compelling new technologies market participants become overly enamored with that attractiveness of the technology and neglect underlying business drivers. This tendency, what some call the “newest shiny object syndrome” is understandable given that virtually all of us are heavily engaged in technology. But it is also mistaken. Without concrete business cases driving its deployment, IoT, like many other technologies before it, will fade into obscurity.
Nov. 30, 2015 07:00 AM EST Reads: 384
Container technology is shaping the future of DevOps and it’s also changing the way organizations think about application development. With the rise of mobile applications in the enterprise, businesses are abandoning year-long development cycles and embracing technologies that enable rapid development and continuous deployment of apps. In his session at DevOps Summit, Kurt Collins, Developer Evangelist at Built.io, examined how Docker has evolved into a highly effective tool for application delivery by allowing increasingly popular Mobile Backend-as-a-Service (mBaaS) platforms to quickly crea...
Nov. 30, 2015 06:00 AM EST Reads: 389
The Internet of Things is clearly many things: data collection and analytics, wearables, Smart Grids and Smart Cities, the Industrial Internet, and more. Cool platforms like Arduino, Raspberry Pi, Intel's Galileo and Edison, and a diverse world of sensors are making the IoT a great toy box for developers in all these areas. In this Power Panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists discussed what things are the most important, which will have the most profound effect on the world, and what should we expect to see over the next couple of years.
Nov. 30, 2015 05:30 AM EST Reads: 496
Growth hacking is common for startups to make unheard-of progress in building their business. Career Hacks can help Geek Girls and those who support them (yes, that's you too, Dad!) to excel in this typically male-dominated world. Get ready to learn the facts: Is there a bias against women in the tech / developer communities? Why are women 50% of the workforce, but hold only 24% of the STEM or IT positions? Some beginnings of what to do about it! In her Day 2 Keynote at 17th Cloud Expo, Sandy Carter, IBM General Manager Cloud Ecosystem and Developers, and a Social Business Evangelist, wil...
Nov. 30, 2015 04:00 AM EST Reads: 609
PubNub has announced the release of BLOCKS, a set of customizable microservices that give developers a simple way to add code and deploy features for realtime apps.PubNub BLOCKS executes business logic directly on the data streaming through PubNub’s network without splitting it off to an intermediary server controlled by the customer. This revolutionary approach streamlines app development, reduces endpoint-to-endpoint latency, and allows apps to better leverage the enormous scalability of PubNub’s Data Stream Network.
Nov. 30, 2015 04:00 AM EST Reads: 350