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EETE JAN 2015

Cloud computing European server project promotes ARM on FDSOI By Peter Clarke A colaborative European microserver project has teamed processor IP licensor ARM and chipmaker STMicroelectronics up with a number of academic and commercial computer and software specialists to try and make technical progress in microservers. The three-year project, which started September 2013, is expected to deliver an innovative scalable computer system architecture this year and a hardware-software prototype implementation by the end of 2015. The rise of cloud-enabled smart devices, cloud-based client services and the Internet of Things (IoT) is expected to create an opportunity as they will drive a shift in the needs of the IT infrastructure which is already under pressure to reduce power consumption even as it tries to scale up to serve increasing numbers of applications. The Euroserver project is advocating the use of low-power ARM processors in a server architecture that uses 3D integration to scale processors, memory and I/O, all managed by systemwide virtualization and efficient use of resources by cloud applications. The group is aiming for Compute unit. Source: ARM. a factor of ten improvement in energy efficiency over traditional server and microserver architectures. Microservers are typically servers designed to serve applications that don’t individually require high levels of computing performance but that may have to be done in large numbers and or may have critical latency aspects to performance. In the past servers tended to aim at ever higher performance and in recent years were the almost exclusive domain of the x86 processor architecture of Intel. Lower power microservers are now expected to take up an increasingly diverse number of data handling opportunities. And microservers have long been the chosen ground on which ARM has chosen to fight Intel in data centre. John Goodacre, director of technology and systems at ARM and a visiting professor of computer architectures at the University of Manchester, said that the groups collaborating in Euroserver reflect the microserver profile. “TU Dresden is interested in the handling of databases in embedded telecom. Eurotech is a systems company looking at more deeply embedded applications,” said Professor Goodacre. He also noted that that Spain’s Barcelona Supercomputing Center is present which reflects an interest in scaling up to take on high performance computing. The unit of compute The Euroserver project is leveraging the availability of an octacore processor chip that ST makes on its FDSOI manufacturing process and also sees importance in using the latest 3D manufacturing techniques, courtesy of project participant CEA-Leti to build the best power-performance trade off it can. “We’ve tried to take a holistic view of the challenge. It’s a mixture of both hardware and software,” said Professor Goodacre. One of the foundation stones of the Euroserver project is an idea that Professor Goodacre laid out in a keynote speech at the DATE conference in 2013 – the ‘Unit of Compute.’ This is the idea of what is the minimum requirement within a computer node to allow its memory to be used by the outside world coherently with a minimum of overhead. A ‘unit of compute’ is managed by a single symmetric multiprocessing (SMP) operating system within a coherent region of memory. It has a processor system – from one to many cores – local memory, provides a coherent view of its memory to the outside world and has a path to access remote memory attached to other ‘units of compute.’ The net result allows the simplification of memory handling compared with traditional server computer architectures and is scalable. And such simplification can result in energy saving argues Professor Goodacre. The Unimem model The project has developed a universal memory model or Unimem to build on this by making a the memory a key focus of the architecture and dispensing with some traditional cache coherency requirements that have traditionally been implemented in servers. In a presentation Professor Goodacre observed that there is no need for sequential consistency to be imposed in most data centre workloads. Applications tend to partition datasets and it is best to place the processor and its cache near the dataset of a particular application task. In other words, rather than moving data sets around at great energy expense in terms of moving data and imposing cache coherency requirements it is more energy efficient to keep the data set still and move the task to a processor that is near the required data set. “We have tried to come up with a softwarecentric architecture,” said Professor Goodacre. The Unimem approach not only maintains a consistent and coherent access Server in a package, potentially including hybrid memory cubes. 6 Electronic Engineering Times Europe January 2015 www.electronics-eetimes.com


EETE JAN 2015
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