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Keywords
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AC | Alternating current. |
ACNT | A term commonly used to describe the IA32_APERF MSR used to calculate average frequency over a user-defined time window. |
ACPI | The Advanced Configuration and Power Interface is used by BIOS to expose platform power management capabilities. |
APIC | Advanced Programmable Interrupt Controller. |
AR | The application ratio is used to describe the CPU logic switching rate of a workload. |
ASHRAE | American Society of Heating, Refrigerating, and Air-Conditioning Engineers. |
ASPM | Active State Power Management is a feature used to manage the power of PCIe links. |
Avoton | Codename for Atom C2000-series SoC that follows Centerton. |
AVX | Advanced vector extensions are integer and floating-point instructions used to improve performance. |
Bin | A term used to describe the increase in frequency between any two P-states Pn and Pn-1. |
BIOS | Basic Input/Output System refers to the firmware used to initialize a server. |
BMC | The baseboard management controller is a dedicated microcontroller that provides remote monitoring and management functionality. |
CC0/CC1/CC3/CC6 | Describes a specific core-level C-state. |
Centerton | Codename for Atom S1200-series processor. |
CKE | The clock enable signal is commonly used to identify rank-level power down modes for memory. |
CLST | Closed Loop System Throttling is a power management feature that enables hardware protection using Node Manager and a PMBus power supply. |
CLTT | Closed Loop Thermal Throttling utilizes temperature monitoring to manage memory thermal throttling. |
CPI | Cycles per instruction is a basic performance metric. |
CPU | Central processing unit. |
CPUID | CPU identification instruction used to discover processor type and features. |
CRAC | Computer room air conditioner. |
CRAH | Computer room air handler. |
CSR | A control and status register frequently used for power management monitoring or control. |
C-state | An idle state where the processor has halted execution of instructions. |
DC | Direct current. |
DPC | The DIMMs per channel is a ratio used to describe the memory population of a platform. |
DRAM | Dynamic Random Access Memory. |
D-state | A low-power idle state for devices (PCIe, SATA). |
DTSMAX | The maximum allowed temperature of the processor. |
Dynamic Switching | A processor power management feature that automatically switches a platform to performance mode when capacity is high. |
EBS | Event-based sampling is a monitoring technique that allows operators to associate power and performance events with the specific modules, functions, and lines of code that caused them. |
ECC | Memory error correction used to provide protection from both transient errors and device failures. |
EDP | The electrical design point |
EEE | Energy efficient Ethernet is a low power mode that reduces PHY power. |
EN | Identifies a platform or processor as Entry Level (Xeon E3 for one-socket servers). |
Energy Perf Bias | A model-specific register used to control how aggressively power management features will be used. |
Entry Latency | The time it takes to transition from an active to idle state (typically measured in microseconds). |
EP | Identifies a platform or processor as efficient performance (Xeon E5 for two- to four-socket servers). |
EPA | Environmental Protection Agency, responsible for the Energy Star program. |
EX | Identifies a platform or processors as expandable (Xeon E7 for 4-socket and larger servers). |
Exit Latency | The time it takes to transition from an idle to active state (typically measured in microseconds). |
FIVR | A Fully Integrated Voltage Regulator is a high-current switching regulator integrated into the processor. |
G-state | A global state that identifies the overall power state of a platform. |
Haswell | Codename for the Xeon E5 v3 processor that follows Ivy Bridge. |
HDD | A hard disk drive is a traditional spinning hard drive. |
HIS | Integrated heat spreader. |
HLT | Halt instruction used by an operating system to enter a C1 state. |
HPC | High performance computing. |
HSC | Hot swap controller. |
HT | Hyper-Threading technology is Intel’s implementation of simultaneous multithreading. |
I/O | Input/output is used to describe capabilities for communication such as DDR, PCIe, and coherent interconnects such as QPI. |
IA | The Intel Architecture term is commonly used to identify a hardware feature unique to Intel products. |
IB | InfiniBand is a low-latency and high-throughput communications link frequently used in high performance computing. |
ICCMAX | The maximum current power delivery a platform can supply. |
IMON | A voltage regulator current monitor used to measure power. |
IPMI | The Intelligent Platform Management Interface is a specification and operating system independent interface for remote management. |
ITD | Inverse temperature dependence. |
Ivy Bridge | Codename for the Xeon E5 v2 processor that follows Sandy Bridge. |
LDO | Low-dropout regulators used to provide variable voltages across cores in a processor with a single input voltage. |
Linpack | An HPC benchmark derived from a collection of Fortran linear algebra routines. |
L-state | A low-power idle state for interconnects (PCIe, DMI, QPI). |
MBVR | A motherboard voltage regulator. |
MCNT | A term commonly used to describe the IA32_MPERF MSR used to calculate average frequency over a user-defined time window. |
MCP | A multi-chip package is where multiple chips are integrated together in the same package. |
ME | The (Intel) Management Engine in the Platform Controller Hub used for monitoring, power capping, and hardware protection. |
MMIO | Memory mapped I/O. |
MSR | A model-specific register frequently used for power management monitoring or control. |
MWAIT | A Monitor Wait instruction used by an operating system to enter a C1 or deeper C-state. |
Nehalem | Codename for the Xeon 5500 processor. |
NTB | Non-transparent bridging is a support technology used to create non-coherent interconnects between nodes using PCIe. |
NUMA | Non-uniform memory access allocation provides contiguous memory regions for each processor’s local memory. |
NVMe | Non-Volatile Memory Express is a specification for directly connecting SSDs on PCIe that provides lower latency and higher performance than SAS and SATA. |
OEM | Original equipment manufacturer. |
OLTP | Online transaction processing. |
OLTT | Open loop thermal throttling utilizes a static bandwidth limit to manage memory thermal throttling. |
OS | Operating system. |
OSPM | Operating system power management is a term commonly used to describe operating system power management policies and device drivers. |
P1 frequency | Represents the CPU base frequency, guaranteed frequency, or the marked frequency of a CPU. |
Path Length | Path length is a basic performance metric that measures the average number of instructions it takes to complete a single unit of work. |
PC0/PC1/PC2/ PC3/PC6 | Describes a specific package-level C-state. |
PCH | Also known as South Bridge, Platform Controller Hub is a chipset connected to the processor that integrates many features that would otherwise require discrete controllers (such as storage, network, USB, management, and legacy). |
PCIe | Peripheral Component Interconnect Express is a high-speed serial communication bus. |
PCM | Performance Counter Monitor is a set of stand-alone tools used to collect core and uncore power and performance events. |
PCPS | Per-core P-states allows individual cores that can each operate at their own frequency and voltage independent of what P-state other cores are in. |
PCU | The power control unit is an internal microcontroller used to facilitate CPU power management. |
PECI | The Platform Environment Control Interface is an interface for management controllers to communicate with the CPU. |
PL1/PL2/PL3 | A power level indicates a specific power limit used for power capping and power delivery protection. |
P-Limit (I/O) | A power management feature that allows the uncore to autonomously increase its uncore P-state to improve PCIe performance. |
P-Limit (perf) | A power management feature that allows an idle socket to increase its uncore P-state to improve snoop and memory latency. |
PLL | Phase-locked loop used to drive clocks. |
PMBus | Power Management Bus is an open standard protocol used for power management of power supplies. |
PMIC | A power management integrated circuit is applied to integrated circuits that have multiple power conversion controllers in one small package. |
Pn frequency | Represents the lowest frequency P-state or the most energy efficient frequency. |
P-state | A performance state is an active state that represents a fixed frequency and voltage operating point. |
PSU | Power supply unit. |
PUE | Power usage effectiveness is defined as the ratio of the total energy use by the datacenter to that of the energy used by the IT equipment. |
PWM | Pulse-width modulation. |
QPI | QuickPath Interconnect is used for multi-socket communication. |
RAPL | Running Average Power Limit is a power management feature used to maximize performance while meeting a specific thermal or power constraint. |
RDTSC | Read time stamp counter instruction used by software to measure time. |
Sandy Bridge | Codename for the Xeon E5 processor that follows Westmere. |
SAS | Serial attached SCSI is a common protocol for connecting disks to a storage controller. |
SATA | Serial ATA is a common protocol for connecting disks to a storage controller. |
SEL | The System Event Log is a centralized event log used by management firmware. |
Self-refresh | A low power memory power state where the DIMM itself is responsible for handling refresh. |
SKU | The stock keeping unit term is commonly used to identify a CPU by its specific features (microarchitecture, core count, frequency, TDP). |
SmaRT | Smart Ride Through is a technology that allows a server to function through momentary loss of AC power. |
SMBus | The System Management Bus enables lightweight communication between platform devices. |
SMT | Simultaneous multithreading. |
SoC | A system on a chip is the coupling of the CPU with special-function hardware components in the same die. |
SPEC | The Standard Performance Evaluation Corporation creates and maintains server benchmarks. |
SRAM | Static random access memory. |
SSD | Solid-state disk drive is a high-performance hard drive that stores data in flash memory chips. |
S-state | A sleep state that powers down most platform components. |
SVID | Serial VID is a serial communication bus between the processor package and the voltage regulator controllers. |
TC0/TC1/TC3/TC6 | Describes a specific thread-level C-state. |
TCO | Total cost of ownership is a metric that estimates both the direct and indirect costs of a system. |
TDP | A thermal design point specifies the amount of power that the CPU can consume, and therefore the amount of heat that the platform must be able to remove in order to avoid thermal throttling conditions. |
THERMTRIP | A term used to describe the catastrophic trip temperature that, when exceeded, will result in immediate hardware shutdown. |
TIM | Thermal interface material fills the air gaps between the component being cooled and a heat sink. |
Tj | The junction temperature describes the internal temperature of the die. |
TPC | The Transaction Processing Performance Council creates and maintains server benchmarks. |
TSC | Time Stamp Counter. |
TSOD | Thermal sensor on die is a thermal sensor used in memory to measure temperature. |
T-state | An active state where core execution is duty-cycled at a fixed interval for thermal, electrical, or power reasons. |
Turbo frequency | Represents opportunistic frequency range about the CPU base frequency. |
UFS | Uncore Frequency Scaling describes a power management feature that allows the uncore to maintain its own P-state. |
UMA | Uniform memory access allocation interleaves every other cache line across each processor’s local memory. |
Uncore | A term commonly used to describe processor on-die logic outside of the cores. |
USB | Universal Serial Bus. |
Vmin | The minimum voltage used for the lowest frequency P-state. |
VMM | Virtual machine monitor. |
VR | Voltage regulator. |
Vret | The retention voltage required to maintain state in a circuit. |
VT | Virtualization technology is a term commonly used to describe technologies used to improve performance in a virtualized environment. |
Westmere | Codename for the Xeon 5600 processor that follows Nehalem. |
Xeon E3 | Processor type used in one-socket servers for workloads with low compute requirements. |
Xeon E5 | Processor type used in two-socket servers for most workloads. |
Xeon E7 | Processor type used in 2-socket to 256-socket servers for mission critical and scale-up workloads. |
Xeon Phi | Coprocessors used to accelerate workstation and cluster performance typically used in HPC. |
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Gough, C., Steiner, I., Saunders, W. (2015). Technology and Terms. In: Energy Efficient Servers. Apress, Berkeley, CA. https://doi.org/10.1007/978-1-4302-6638-9_10
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