Beyond Multicore CPUs

Breaking the Barriers of Cores

New Tech in Server CPUs

Multi Core Processors

Getting to the 'Core' of Processors

Think about the common processing issues you have with the servers in your data center: the inability to add specialized processors to handle different kinds of workloads, floating point precision errors when doing financial calculations requiring further adjustments and problems of compatibility and interoperability between what you had and what you want to have.

Some of the processors that are slated for imminent release through 2007 and early 2008 include a bundle of new technologies that will make
these problems a thing of the past. These processors are spread across both the x86 and non-x86 platforms. This story looks at these technologies and the benefits they will provide to you.

Decimal math
As kindergarten kids, we learnt how to count and do things with numbers using our ten fingers. Ancient mathematicians translated this into decimal mathematics. The infamous original Pentium 1 floating point precision error proves dramatically fatal when you use computers to calculate missile firing tables, launching spacecraft, synchronizing automatic medication equipment or robotic surgical arms, performing year end financial calculations and the like. This was because it had a floating point bug related to dividing two decimal system numbers using binary math.

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New CPUs like the expected IBM Power6 processor will include the ability to do math within the processor using the decimal number system (1,2,3,...) instead of the binary (0s and 1s). It is easier and faster for the processor (being an electronic state device) to process 1s and 0s against decimal numerals and math, and binary will still be the way it does all other processing.

CPU-based VMX
Also known as AltiVec, this is an instruction set that can apply a single processing instruction to multiple data elements. This finds varied usage in servers: one can use it to perform business data analysis, genetic data processing as well as backend video and audio rendering. The technology was created by Freescale and implemented as VMX by IBM and as Velocity Engine by Apple. The instruction set, though developed in the late 1990s, was used by a variety of applications including Adobe Photoshop, Mac OS X, iTunes and QuickTime, will be seen for the first time in a server-class CPU, the IBM Power6.

Hot spare cores
Hot sparing, as you know, is the technology that lets you switch to a secondary component while the system is turned on and functioning without needing to bring down the system to make the switch. So far, we've seen this applied to storage, power supplies and memory. Now, you can hot-spare processor cores as well.

The system automatically and continuously monitors data in the processor cache. When errors are detected, attempts are made to reload the data and continue or repeat the last instruction step. If further errors are encountered, the entire core is hot-spared to a new core in the server and an alert is raised to the server administrator to troubleshoot the problematic processor or core.

Innovation Socket
While Intel has been busy stuffing as many cores into a single die as can be done, AMD decided to simply add more processor sockets to their motherboards and open up the socket specification. This would let you add specialized processors into sockets you are not plugging multi-core Opteron chips into. Such chips are envisaged to be dedicated encryption/decryption engines and Java processors among other possibilities. So, you would take a '4x4' board (as they are called), add say two Opteron dual cores and one Java processor and increase the computing power of your server manifold if your processors spend a lot of time otherwise doing Java. AMD calls this capability 'Torrens' and this kind of a socket the 'Innovation Socket.'

Time for standardization
The industry has agreed that multi-core hardware and software today are built around proprietary specifications and realizes that there is a need for a more 'heterogeneous embedded distributed system.' The body behind this is called the 'The Multicourse Association,' and they are working towards standards to create programmable application interfaces (API) for resource management, communication and transparent inter-process communication.

To contribute to this, the EMBC (Embedded Microprocessor Benchmark Consortium) has started work on building some kind of benchmarking and assessment methodology for multi-core processors. These tools are expected to become available as early as Q2 of 2007. For now the EMBC's focus will be on building tools to assess the same kind of cores in a system (eg: all dual core chips) as against different kinds of cores (eg: a dual core and a quad core) in the system.

Mind the memory
Consider a server with 8 CPUs with two cores each, making for a total of 16 processing cores. Now, how would this system ensure trouble and error free memory access? If you also consider technologies like AMD's Direct Connect Architecture (discussed last month, Pg 54) which lets the processor core manage memory via the HyperTransport Controller rather than using a Memory Controller, the situation gets complicated as you increase the number of cores.

To help ease the situation, processors like IBM's Power6 will use a two-layer mechanism to inter-communicate. Here each core would bond directly (core to core) to three other cores on one layer, each of this group of four cores would connect to seven other groups (a total of eight core groups or 32 cores in all) using a second layer. This, they say, will keep their cache memories in sync.

Stay tuned to this series for more on the latest technologies as well as the technology behind the buzzwords rolling out to power processors of the

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