In the past, when it came to processor thermal and power management for most high performance Intelligent Systems used in military applications, the only option was “let it burn.” Processor clocks were locked into full speed mode all the time regardless of the current operational situation. The critical nature of many military applications demands that the system be running 100% clock speed all the time to address immediate processing needs. But today that is changing in many cases as better processor thermal management techniques have evolved.
Thermal and power management are ongoing challenges that designers of intelligent systems face every day. In higher end systems the traditional solutions have usually been focused on the thermal aspects and even that has been restricted to creative ways to mechanically move heat from one place to the next. With the 3rd Generation Intel® Core™ processors, there are more processor management options available through software that gives system designers and users more control than ever.
3rd Generation Intel® Core™ processors have Enhanced Intel SpeedStep® Technology and Thermal Monitoring Technologies to provide thermal management support. Conventional Intel SpeedStep technology switches both voltage and frequency in tandem between high and low levels in response to processor load. Enhanced Intel SpeedStep Technology builds upon that architecture using design strategies that include the following:
- Separation between voltage and frequency changes. By stepping voltage up and down in small increments separately from frequency changes, the processor is able to reduce periods of system unavailability (which occur during frequency change). Thus, the system is able to transition between voltage and frequency states more often, providing improved power/performance balance.
- Clock partitioning and recovery. The bus clock continues running during state transition, even when the core clock and phase-locked loop are stopped, which allows logic to remain active. The core clock is also able to restart far more quickly under Enhanced Intel SpeedStep Technology than under previous architectures.
Included in Thermal Monitoring Technologies are the following capabilities:
- Digital Thermal Sensor
- Intel Adaptive Thermal Monitor
- THERMTRIP# and PROCHOT# support
- On-Demand Mode
- Memory Thermal Throttling
- External Thermal Sensor (TS-on-DIMM and TS-on-Board)
- Render Thermal Throttling
- Fan speed control with DTS
The first level of control begins at the BIOS. The BIOS is responsible for providing sensor data to the operating system so that the OS does not need to know about all the particular details of the processor. Through the BIOS you can set trip points, control fans, and monitor the thermal sensors for each core in a multicore processor. The BIOS passes critical information to the operating system that can be made available to an application if necessary. The OS or the appropriate application can then make decisions on how they want the processor to perform in given operating conditions. It is important that the BIOS provides the first level of control otherwise the OS would have to know specific details about many different processors, adding unnecessary complexity to the operating system. The BIOS is closer to the specific hardware and can be optimized for that particular platform and processor as necessary.
The Advanced Configuration and Power Interface (ACPI) specification was developed to establish industry common interfaces enabling robust operating system (OS)-directed motherboard device configuration and power management of both devices and entire systems. ACPI is the key element in Operating System-directed configuration and Power Management (OSPM).
ACPI evolved the existing pre-ACPI collection of power management BIOS code, Advanced Power Management (APM) application programming interfaces (APIs, PNPBIOS APIs, Multiprocessor Specification (MPS) tables and so on into a well-defined power management and configuration interface specification. ACPI provides the means for an orderly transition from existing (legacy) hardware to ACPI hardware, and it allows for both ACPI and legacy mechanisms to exist in a single machine and to be used as needed.
The specification enables new power management technologies to evolve independently in operating systems and hardware while ensuring that they continue to work together. The interfaces and OSPM concepts defined within this specification are suitable to all classes of computers including (but not limited to) desktop, mobile, workstation, and server machines. From a power management perspective, OSPM/ACPI promotes the concept that systems should conserve energy by transitioning unused devices into lower power states including placing the entire system in a low-power state (sleeping state) when possible.
Becoming a bigger part of the layers between the processor and operating system is the Unified Extensible Firmware Interface (UEFI). The UEFI specification defines a new model for the interface between operating systems and platform firmware. The interface consists of data tables that contain platform-related information, plus boot and runtime service calls that are available to the operating system and its loader. Together, these provide a standard environment for booting an operating system and running pre-boot applications. Intel has recently launched a new website, the Intel UEFI Community Resource Center, that is your gateway for developing UEFI firmware, drivers, and applications for use on Intel® architecture platforms.
The Phoenix Technologies flagship product line, Phoenix SecureCore Technology™ (SCT) has two BIOS offerings, Phoenix SecureCore and their UEFI product, SecureCore Tiano. SCT addresses the needs of the embedded market with Phoenix’s leading technology in system security and connectivity. Tailored to the needs of embedded applications, SCT is the ideal solution for intelligent system developers seeking security, performance, and interoperability with cloud computing. For Power Management, SCT supports ACPI 5.0 and Win8 Connected standby (with TPM2.0 support).
Insyde Software offers InsydeH2O®, a UEFI BIOS, that is claimed to be the most widely used UEFI BIOS in production. Insyde targets embedded and mobile applications with InsydeH2O. Enhanced SpeedStep is supported as well as S-state and C-state power management giving developers access to critical parameters to manage the thermal characteristics of their embedded system.
American Megatrends Inc. (AMI) provides BIOS and UEFI firmware for Intel processors. The AMI options include AMIBIOS® 8, Aptio®, and Aptio® V, with the Aptio products being UEFI compliant. AMIBIOS provides built-in power management support for Enhanced SpeedStep and Thermal Monitoring Technology. Users can control the C-states of the processor through the BIOS setup screen.
Aptio is built around Visual eBIOS (VeB), the innovative BIOS development environment introduced by AMI in 2001. VeB simplifies BIOS development worldwide by removing barriers normally associated with BIOS development in the command line environment. Aptio builds on that experience, providing next-generation BIOS firmware leveraging UEFI standards for extended pre-boot functionality.
The following screenshot shows some of the platform thermal configuration settings that can be configured to execute at boot time. The operating system can then use this information to manage the platform.
While the main function of the BIOS may be to act as a kind of translator between the processor/board and the operating system, it is an extremely important role in simplifying the interaction. Embedded devices are becoming ever more ubiquitous and intelligent, demanding improved power consumption and management capabilities so be sure that your BIOS is up to the task.
Military systems developers have options for power and thermal management, they can maintain the high performance they require but extend system life (and battery life for mobile systems) for some efficiency and cost gains.
Intel Embedded to learn more about BIOS support options.
For more on energy efficiency, see Energy Efficiency - Top Picks
American Megatrends Inc. (AMI) and Phoenix Technologies are Associate members of the Intel® Intelligent Systems Alliance. Insyde Software is an Affiliate member of the Intel® Intelligent Systems Alliance.
OpenSystems Media®, by special arrangement with Intel® Intelligent Systems Alliance