Performance per watt

More efficient use of chip power is one of several benefits MCPs bring to the industrial arena. Rather than push clock speeds to increase performance, with diminishing returns on power consumption, MCPs provide a new direction that Casey Weltzin, product manager for software at National Instruments Inc. (NI), calls “better performance per watt.” Power consumption has become a big issue for traditional (single-core) chip design. “Multiple CPUs on one chip enable computation parallelism at a power cost that scales linearly—not exponentially—with the number of cores,” Weltzin said.

Extra computing cores translate into more compact automation systems which can incorporate more functionality. That added computing power lets MCP users implement more complex control algorithms that do more and run computations in more power-efficient ways, he explained. Advanced software algorithms can complete a process faster, thereby saving some power or other system operational cost.

MCPs permit more than one operating system (OS) on a single controller. Ability to run both real-time functions for deterministic control and general-purpose OS tasks (HMI, networking access, etc.) is a real asset in many industrial automation systems. Moreover, users can plan out how to apply the cores, that is, designate which core(s) will handle which OS or specific control loop. “Designers have traditionally relied on separate hardware pieces to meet this need; now multi-core CPUs combined with virtualization technology reduce hardware costs and footprint,” Weltzin noted. MCPs have wide industrial application potential (see more online).

As a forward-looking implementer of MCPs in its industrial PC (IPC) products, Beckhoff Automation recognizes the multitasking benefits extra cores offer. The company has coined the term “scientific automation” to summarize how engineers can use extra cores on a multi-core IPC to perform numerous parallel tasks, according to Corey McAtee, Beckhoff’s technical marketing manager.

In Beckhoff’s experience, multi-core IPCs can decrease overall power consumption and, as a result, reduce a machine’s “thermal footprint.” Less hardware space needed is an additional benefit. “With a smaller thermal footprint, machine builders can reduce cabinet size or eliminate cooling devices in the control cabinet,” said McAtee.

“Multi-core IPCs on the automation control side of the factory floor provide the greatest benefits to machine builders looking to streamline machine designs and eliminate unnecessary controls components,” McAtee stated. MCPs for the operator interface side of the factory floor pose a different case—as discussed in an online extension.

Ability to dedicate individual processor cores to particular automation tasks is illustrated in Beckhoff’s new TwinCAT 3 software platform scheduled for release in 2Q11 (see image). “Teaming multi-core IPCs with a software package enables users to intelligently take advantage of individual cores within a multi-core processor and enjoy a host of benefits,” McAtee added. “The IPC becomes a powerful device, doing the work of four conventional devices, using one software platform and one network (EtherCAT) with considerably less wiring and programming.”

Freescale Semiconductor Inc. views MCPs as a means to increase performance, while reducing chip count, board size, and power consumption of industrial applications such as programmable logic controllers, motor drives, and robotics. “Yet, multi-core processors can increase thermal and software design complexity and cost,” cautioned Alexandra Dopplinger, Freescale’s global segment lead for Factory Automation & Drives. She explained that lower power consumption doesn’t necessarily simplify thermal design due to the smaller geometry technology on which MCPs are fabricated. “The physics of removing the same amount of heat from a smaller area die can often involve more costly heat sink material, or more complex heat sink geometry,” Dopplinger said.

Importantly, MCPs typically run at slower clock speeds, and two or four cores don’t usually give double or quadruple performance. “However, multi-core architectures can support much higher performance for less cost and power consumption than traditional single-core architectures,” she stated. As an example, Dopplinger cited Freescale’s trademarked QorIQ P4080 communications processor that implements eight 1.5 GHz cores in one chip and provides more than 20,000 million instructions per second (MIPS)—while consuming less than 30 W power. A previous generation single-core processor offered only 3,000 MIPS at the same power level.

Operating systems also represent an important aspect of MCP application. Dopplinger mentioned that in some cases a single core dedicated to make decisions about real-time control of a complex process is appropriate. “However, operating systems like Enea OSE Multicore Real-Time Operating System are designed to optimally distribute software instructions across multiple cores of processors such as Freescale’s QorIQ, while making it seem like the algorithm is running on a single core,” she said. Similarly, functions such as safety controllers often run on separate dedicated processors (see more coverage online).

Дата добавления: 2015-11-16