Technology Brief: DMA Coalescing

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Reducing Data Center Power

Consumption with DMA Coalescing

Intel® Ethernet Server Adapters are the only networking hardware in the industry to offer Direct

Memory Access (DMA) Coalescing, which can reduce platform power by as much as 8 to 12 watts.

Data center operators must strive to reduce utility costs as a component of operating expense to remain competitive.

This requirement has led to the demand for higher energy efciency in computer platforms, but data centers also need

peak performance to meet growing business needs.

The optimal balance between energy efciency and performance is typically obtained by operating at maximum

performance for short durations when needed and then returning to low power states. Direct memory access (DMA)

is one approach to taking advantage of that principle by adding intelligence to the way processor, chipset, and memory

power states respond to DMA interrupts.

System components shift into low power states to reduce energy consumption when network trafc levels and other

workload characteristics allow. The arrival of network data causes the DMA controller to issue an interrupt command

that wakes the processor, chipset, and memory into higher power states.

Intel® Ethernet Server Adapters uniquely offer DMA Coalescing, an innovative capability that batches together DMA

interrupts to be sent to the system for efcient processing. This capability optimizes the utilization of system resources

and allows them to return to a lower power state more quickly than would otherwise be possible. Key aspects of DMA

Coalescing are shown in Figure 1.

Figure 1. Intel® Ethernet Server Adapters are the only network hardware in the industry to offer DMA Coalescing, which lowers overall power consumption.

DMA coalescing in Intel® Ethernet Power Management Technology:

Competitive multi-chip architectures provide no coalescing

Power Consumption

Interrupts can be

synchronized across

the eight ports of

two quad-port Intel®

Ethernet Server Adapters

DMA Coalescing batches

DMA interrupts so the

system can stay in lower

power states longer

Asynchronous network

trafﬁc limits system

time in low power states

TECHNOLOGY BRIEF

Intel® Ethernet Server Adapters

DMA Coalescing

Summary of content (2 pages)

PAGE 1
TECHNOLOGY BRIEF Intel® Ethernet Server Adapters DMA Coalescing Reducing Data Center Power Consumption with DMA Coalescing Intel® Ethernet Server Adapters are the only networking hardware in the industry to offer Direct Memory Access (DMA) Coalescing, which can reduce platform power by as much as 8 to 12 watts. Data center operators must strive to reduce utility costs as a component of operating expense to remain competitive.
PAGE 2
Complementary Aspects of Intel® Ethernet Power Management Technology DMA Coalescing is one aspect of a larger set of capabilities known collectively as Intel Ethernet Power Management Technology. These capabilities work together to create more energy-efficient networking for the enterprise. As shown in Figure 2, different features of Intel Ethernet Power Management Technology contribute more to power consumption reduction at specific network-utilization levels.