Dell Intel PRO Family of Adapters - Manual (Page 51)

Performance Options
Adaptive Inter-Frame Spacing
Compensates for excessive Ethernet packet collisions on the network.
The default setting works best for most computers and networks. By enabling this feature, the network adapter dynam-
ically adapts to the network traffic conditions. However, in some rare cases you might obtain better performance by dis-
abling this feature. This setting forces a static gap between packets.
Default Disabled
Range l Enabled
l Disabled
Direct Memory Access (DMA) Coalescing
DMA (Direct Memory Access) allows the network device to move packet data directly to the system's memory, reducing
CPU utilization. However, the frequency and random intervals at which packets arrive do not allow the system to enter
a lower power state. DMA Coalescing allows the NIC to collect packets before it initiates a DMA event. This may
increase network latency but also increases the chances that the system will consume less energy. Adapters and net-
work devices based on the Intel® Ethernet Controller I350 (and later controllers) support DMA Coalescing.
Higher DMA Coalescing values result in more energy saved but may increase your system's network latency. If you
enable DMA Coalescing, you should also set the Interrupt Moderation Rate to 'Minimal'. This minimizes the latency
impact imposed by DMA Coalescing and results in better peak network throughput performance. You must enable
DMA Coalescing on all active ports in the system. You may not gain any energy savings if it is enabled only on some of
the ports in your system. There are also several BIOS, platform, and application settings that will affect your potential
energy savings. A white paper containing information on how to best configure your platform is available on the Intel
website.
Flow Control
Enables adapters to more effectively regulate traffic. Adapters generate flow control frames when their receive queues
reach a pre-defined limit. Generating flow control frames signals the transmitter to slow transmission. Adapters respond
to flow control frames by pausing packet transmission for the time specified in the flow control frame.
By enabling adapters to adjust packet transmission, flow control helps prevent dropped packets.
NOTE: For adapters to benefit from this feature, link partners must support flow control frames
.
Default RX & TX Enabled
Range l Disabled
l RX Enabled
l TX Enabled
l RX & TX Enabled
Interrupt Moderation Rate
Sets the Interrupt Throttle Rate (ITR). This setting moderates the rate at which Transmit and Receive interrupts are gen-
erated.
When an event such as packet receiving occurs, the adapter generates an interrupt. The interrupt interrupts the CPU
and any application running at the time, and calls on the driver to handle the packet. At greater link speeds, more inter-
rupts are created, and CPU rates also increase. This results in poor system performance. When you use a higher ITR
setting, the interrupt rate is lower and the result is better CPU performance.