Intel Multi-Core Processors: Quick Reference Guide. by Thomas W. Burger

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1 Intel Multi-Core Processors: Quick Reference Guide by Thomas W. Burger August 2005

2 The information contained in this document is provided for informational purposes only and represents the current view of Intel Corporation Intel on the date of publication. Intel makes no commitment to update the information contained in this document, and Intel reserves the right to make changes at any time, without notice. DISCLAIMER. THIS DOCUMENT AND ALL INFORMATION CONTAINED HEREIN IS PROVIDED AS IS. INTEL MAKES NO REPRESENTATIONS OF ANY KIND WITH RESPECT TO PRODUCTS REFERENCED HEREIN, WHETHER SUCH PRODUCTS ARE THOSE OF INTEL OR THIRD PARTIES. INTEL EXPRESSLY DISCLAIMS ANY AND ALL WARRANTIES, IMPLIED OR EXPRESS, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NON-INFRINGEMENT, AND ANY WARRANTY ARISING OUT OF THE INFORMATION CONTAINED HEREIN, INCLUDING WITHOUT LIMITATION, ANY PRODUCTS, SPECIFICATIONS, OR OTHER MATERIALS REFERENCED HEREIN. INTEL DOES NOT WARRANT THAT THIS DOCUMENT OR THE INFORMATION CONTAINED HEREIN IS FREE FROM ERRORS, OR THAT ANY PRODUCTS OR OTHER TECHNOLOGY DEVELOPED IN CONFORMANCE WITH THIS DOCUMENT WILL PERFORM IN THE INTENDED MANNER, OR WILL BE FREE FROM INFRINGEMENT OF THIRD PARTY PROPRIETARY RIGHTS, AND INTEL DISCLAIMS ALL LIABILITY THEREFOR. INTEL DOES NOT WARRANT THAT ANY PRODUCT REFERENCED HEREIN OR ANY PRODUCT OR TECHNOLOGY DEVELOPED IN RELIANCE UPON THIS DOCUMENT, IN WHOLE OR IN PART, WILL BE SUFFICIENT, ACCURATE, RELIABLE, COMPLETE, FREE FROM DEFECTS OR SAFE FOR ITS INTENDED PURPOSE, AND HEREBY DISCLAIMS ALL LIABILITIES THEREFOR. ANY PERSON MAKING, USING OR SELLING SUCH PRODUCT OR TECHNOLOGY DOES SO AT HIS OR HER OWN RISK. Licenses may be required. Intel and others may have patents or pending patent applications, trademarks, copyrights or other intellectual proprietary rights covering subject matter contained or described in this document. No license, express, implied, by estoppels or otherwise, to any intellectual property rights of Intel or any other party is granted herein. It is your responsibility to seek licenses for such intellectual property rights from Intel and others where appropriate. Limited License Grant. Intel hereby grants you a limited copyright license to copy this document for your use and internal distribution only. You may not distribute this document externally, in whole or in part, to any other person or entity. LIMITED LIABILITY. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO YOU OR TO ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY DIRECT, INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF YOUR USE OF THIS DOCUMENT OR RELIANCE UPON THE INFORMATION CONTAINED HEREIN, UNDER ANY CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES. THESE LIMITATIONS SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY LIMITED REMEDY. Intel, the Intel logo, Pentium, Intel Xeon, and VTune are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the United States and other countries. *Other names and brands may be claimed as the property of others. Copyright 2005 Intel Corporation

3 What is Multi-Core Technology? Multi-core means to place two or more complete computational engines (cores) within a single processor. Multi-core technology was developed when engineers realized that merely increasing the speed of single-core chips created too much heat and did not produce the same improvements as in previous processor models. They realized at that rate, a processor would soon be hotter than the surface of the sun. Even without the heat problem, the priceto-performance ratio would be unacceptable, with slightly faster processors costing greatly more. Instead of scaling up, Intel engineers developed multi-core chips to embrace the scaleout approach to performance. This architecture facilitates a divide and conquer strategy. By splitting the work, a threaded application can take advantage of multiple execution cores and can perform more work within a given amount of time. The multi-core processor is a single chip (also known as a die ) and plugs directly into a single processor socket, but the operating system perceives each execution core as a discrete logical processor, with all the associated resources. By dividing the work between two execution cores, a multi-core processor can perform more work within a given clock cycle. What Multi-Core Technology Does Multi-core architecture makes current software work better and creates an architecture that will encourage future software to be written better. With the move to multi-core processors, existing software does not necessarily need to be modified to support multi-core platforms, although serious software vendors are exploring the new models of software concurrency. Operating systems are already designed to take advantage of multiple processors and will work unmodified. Application developers will have to put more thought into the design of their programs to take full advantage of multi-core technology, but the process for them will be the same as it currently is for designing software for symmetric multiprocessing (SMP) systems, and existing single-threaded applications will continue to work. Applications that benefit from being threaded today will show excellent performance scalability when running on a multi-core processor. Software in this category includes multimedia applications (content creation, editing and local and streaming media playback), engineering and other technical computing applications and middle- and back-tier server applications like application servers and databases. Multi-core technology allows servers to run tasks in parallel that previously would have required multiple processors, and multi-core-based systems are more easily scalable and can put more processing power in a smaller package that uses less power and generates less heat for the computational power derived.

4 Multi-Core Technology and Hyper-Threading Technology Multi-core technology is not the same as Hyper-Threading Technology (HT Technology); it s a vast improvement on it. Multi-core technology allows greater flexibility and speed. HT Technology is based on simulating the presence of two processors (creating two virtual processors). Utilizing HT Technology means that the programmer has to be aware that, although two threads can be run at once and each has access to all of the hardware, there is in reality only one set of computational resources. In order to gain full benefit from hyperthreading, work assigned to each thread is as different as possible to ensure there is as little conflict as possible over processor resources. With multi-core technology, each core is complete with its own hardware cache, floating point math unit, integer engine and a programming thread can utilize all of these resources while another thread can use all of the hardware resources on another core. So the number of simultaneous threads is dependant only on the number of cores and not the resources in each core. There is no need to recode HT Technology-enabled programs for multi-core processors. Applications tuned for HT Technology will use the actual cores as it used the virtual processors. Neither do programming techniques have to change. Multi-core technology will allow HT Technology and multi-threaded applications to take advantage of the increased resources. For the application developer, the techniques for writing applications to take advantage of multi-core processors are the same as they are for current multiprocessor systems. Speed Compared to a single-core processor, a multi-core processor with two cores is not twice as fast as a single-core processor of the same speed, but it can come close. Tests show the addition of a second processor can increase processing speed up to 93%. Tests using dual-processor (DP) workstation platforms based on Intel E7525 chipset and 64-bit Intel Xeon processor 3.60 GHz with 2M L2 cache provide up to 93% additional performance with the addition of the second processor for the threaded workstation applications tested. Performance will vary depending on the specific hardware and software used. This is applicable not only for socket-to-socket scalability but also for internal, or core-tocore, scalability between multiple cores. As an example, say that core-to-core scalability is estimated at 80 percent, meaning that the second core delivers 80 percent of its processing power. A 2.2 GHz dual-core processor would perform like a 3.96 GHz single-core processor. At the same time the 2.2 GHz dual-core processor would have similar characteristics (cost, power usage, cooling requirements) as a 2.2 GHz single-core processor. The (hypothetical) 3.96 GHz processor would cost far more, use much more power, and generate enormous amounts of heat, and because of this, does not exist.

5 Legacy Software and Development Most of the operating systems currently on the market, including the current versions of Windows*, Linux*, and UNIX* operating systems, support multiple processors and will treat a multi-core system as if it were a multiple processor system. Any software that uses threading or is HT Technology-enabled can immediately take advantage of multi-core technology. To date, more than 150 client applications have been enabled for HT Technology, on top of the many hundreds of applications that have previously been threaded. Additionally most major server applications (databases for example) have long been designed to take advantage of multiple processors. These numbers demonstrate that many developer resources and design tools are already in place to capitalize on select Intel processors multi-core capability so current software development efforts aimed at multiple processor systems will work as is with multi-core systems and will take advantage of multi-core technology. The programming community is supporting multi-core technology, and many examples of multi-core technology are the catalyst for renewed efforts in increasing multi-core support. For example, to write software that can take full advantage of multi-core processors, Peter Buhr, professor of computer science at the University of Waterloo, has developed four new C++ classes not in the original language specifications. Professor Buhr states, You won't be able to buy a computer in five years that doesn't have a dual-core processor. We can ignore it, or we can try to get software in place so that every programmer has an opportunity to take advantage of this. Additionally, the C++ standards committee is currently considering revisions that fold multithreading features into the definition of the language. Multi-Core Technology Has Great Advantages for Existing Software More, software is being designed to run with multiple threads. However, older legacy applications, designed to run single-threaded on single-core systems, can still take some advantage of multi-core technology in a typical multitasking environment even though the applications won t know that multiple processors exist. The operating system is aware of multi-core technology and schedules multiple processes amongst the multi-core architecture greatly increasing system throughput. The operating system has a CPU scheduler, which keeps track of all of the tasks that are running and switches between them, assigning each task to the CPU for a short time. It appears that all of the applications are running simultaneously when only one is executing at any given moment. Each switch of the running task is called a context switch. This involves the following procedures: Backing up all of the data stored in the registers that relate to the old task Loading the registers that allow the operating system s CPU scheduler to run Running the scheduler to decide which task to run next Loading the registers for the next task

6 By using multi-core technology, the constant overhead of switching tasks is greatly reduced, resulting in much less overhead and greater code processing. Scalability Multi-core technology allows even more ease of hardware scalability by requiring only a single socket. Instead of having to replace computers to increase the number of processors you can simply replace the single multi-core processor with one containing more CPU cores. Compatibility There is no problem mixing various single- and multiple-thread programs on an multi-core computer. Operating systems will see and use multi-core processors as any other system and schedule each task correctly. More software will be designed to take advantage of multi-core technology as it gains in popularity, and multi-core-based computers will only provide greater and greater advantages in speed, scalability, and flexibility. Price How much will multi-core technology cost? Multi-core technology will cost less than an equivalently fast single-core processor, both in terms of initial price and overhead use. Why Multi-Core? Multi-core technology will be the predominant server and desktop technology. For maximum business advantage and IT potential, multi-core technology is the technology that will drive business in the months and years to come The Intel Multi-Core Technology Advantage Intel adds value to multi-core technology by developing features that take advantage of multi-core architecture to further improve performance and savings. Intel has developed energy-saving dynamic power-coordination (DPC) technology that, when workloads permit, lets the OS tell one processing core to sleep or slow down while the other works. A Product-Wide Application of Multi-Core Technology Intel has multi-core technology solutions for servers, workstations and laptops. Intel plans to integrate DPC, which would extend battery life, into Yonah, Intel s first dual-core laptop chip. Yonah is slated for release later this year. Multi-Core Processor Licensing Do multi-core processor-based systems with four cores mean the processor-based licensing fees are now four times higher? Microsoft, the world s largest software vendor, has announced that they will consider a multi-core processor as a single processor for licensing purposes.

7 Microsoft has also announced that Windows XP and Windows server* 2003 operating systems will count only physical processors (not cores) toward the license fee. Currently, some operating systems and enterprise level applications, such as database servers, are licensed on a per-processor basis with the assumption that each chip is a single processor. With multi-core architecture placing additional processor cores on a single chip, each software vendor must reevaluate and clarify what it considers to be a processor. To allay customer concerns regarding multi-core processors, some software vendors have already announced license policies to include multi-core processors. Taking Advantage of Multi-Core Technology Three steps: Upgrade, improve efficiency, and optimize software. Step one is to upgrade processors. Multi-core technology is a flexible technology that IT administrators can use to provide the breathing space required to support business growth (increases in users, transactions, and data) without having to upgrade the entire Delor Katheryn - kdelor [kdelor@digitalimpact.com] server. This strategy enhances scalability for future growth while, at the same time, extending the life of existing data center components. Administrators can use multi-core technology to optimize the performance of repurposed platforms when next-generation applications are deployed. The second step is improving the efficiency of computer platforms by harnessing multicore technology. Servers with multiple processors have been available for many years, and most networked applications can take advantage of the additional processors, multiple software threads, and multitasked computing environments. This allows organizations to scale networked applications for greater performance. The next logical step for multiprocessing advancements is multi-core technology to further add performance and scalability for future growth. The third step is software optimization. Using multi-core technology as an efficient way to enable incremental performance gains without increasing power consumption and heat. Software tools, along with Intel compilers, can enable significant performance improvements over applications that have not been threaded, compiled, or tuned using such optimization tools. Who will Benefit from Multi-Core Technology? Everyone will benefit. Multi-core technology provides more processing at a lower price with lower power consumption and heat problems. With multi-core processors, users no longer have to wait for multiple programs to load. Multitasking takes place without encountering the delays that even the fastest single-core processors encounter on a regular basis and smoothes out the desktop experience. Multitasking users and those working in environments with background processing will benefit from Multi-core based systems. Using background processing is increasingly

8 widespread in business computing environments. Examples of multitasking processes include background data mining queries while working on spreadsheets, or corporate IT department s management tasks over the corporate network like updating software, troubleshooting hardware, and performing virus scanning. Multi-core processors will allow corporate developers and solutions architects to offer both improved application performance with decreased storage and energy costs and multiprocessing advantages with a lower total cost of ownership and a smaller footprint. As multi-core technology becomes omnipresent it would be a great advantage for developers to embrace multi-core technology. More information on threading resources can be found at the Intel Software Network ( to help programmers navigate this transition. Where? Multi-Core Technology is the Future of the Intel Inside Program Intel is placing a huge investment and effort into multi-core technology. The next step in processor hardware evolution is multi-core processors. This is expected to be adopted by the major software producers even more readily than HT Technology. Intel is working on 16 multi-core chip projects: Two Intel Pentium processor chips will use the dual-core technology, code-named Smithfield. Intel s high-end PC chip, the Pentium Processor Extreme Edition 840, has begun shipping and runs at 3.2 GHz but outperforms today s high-end, single-core, 3.8-GHz Pentium 4. The Pentium D processor, slated for release this year, will be a mainstream desktop chip. Intel plans to release two dual-core Intel Xeon brand server and workstation processors early next year: Intel Xeon multi-processor (MP) chips for servers running at least four processors and Intel Xeon dual-processor (DP) chips for servers and workstations. A dual-core Intel Itanium brand server chip scheduled for release later this year will contain 1.7 billion transistors. It will be Intel s first processor with more than 1 billion transistors. When? The move to threading and concurrency in software will be pulled along by the rapid transition to multi-core architectures. By the end of 2006, the Intel Pentium processor family of multi-core processors is expected to comprise 70 percent of all shipped desktop and mobile processors. In enterprise computing, 85 percent of shipped server processors will be multi-core Intel Xeon and Intel Itanium processors. Intel has more than a dozen multi-core related projects underway for the server, desktop and mobile market segments. The projected platform release date for first the Intel Itanium 2 dual-core processor is Q4 2005; for both the first Intel Xeon dual-core processor and the first Intel Xeon dual-core processor MP, Q1 2006; and for the first Intel Pentium M dual-core processor, also Q

9 In February 2005, Intel announced that it had completed initial production runs of its dualcore desktop silicon and by April 2005, computer manufacturers Alien ware, Dell and Velocity Micro were selling desktop PCs and workstations based on Intel's first dual-core processor-based platform. Intel's first dual-core processor-based platform includes the Intel Pentium Processor Extreme Edition 840 running at 3.2 GHz and the Intel 955X Express Chipset. The Intel Pentium Processor Extreme Edition 840 is priced at $999 and the Intel 955X Express Chipset is priced at $50 in 1,000-unit quantities. Dell plans to begin integrating MC processor designs into Dell PowerEdge* and Dell PowerEdge SC* servers during the next 12 to 18 months as multi-core processors become available. Through Dell s close relationship with Intel, Dell intends to deliver solutions built on Intel Xeon, Pentium 4, and Itanium multi-core processors. Dell is working closely with Intel to ensure that the next generations of PowerEdge and PowerEdge SC servers are designed to meet both the performance and scalability needs of enterprises in relation to multi-core processor architectures. About the Author Thomas Wolfgang Burger is the owner of Thomas Wolfgang Burger Consulting. He has been a consultant, instructor, analyst, and applications developer since He can be reached at twburger@shaw.ca Additional References

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