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Intel® Data Direct I/O (Intel® DDIO) Frequently Asked Questions (External)

Intel® Data Direct I/O: Frequently Asked Questions

What is Intel® Data Direct I/O?
A1: Intel® Data Direct I/O (Intel® DDIO) is a feature to be introduced on the Intel® Xeon® processor E5 series. Intel's LAN Access Division (LAD) worked for the incorporation of Intel DDIO into the Intel Xeon processor E5 because of its benefits for LAN I/O in terms of performance and system power consumption. With Intel DDIO, Intel's Ethernet server NICs and controllers talk directly to the processor cache without a detour via system memory. Intel DDIO makes the processor cache the primary destination and source of I/O data rather than main memory. By avoiding system memory, Intel DDIO reduces latency, increases system I/O bandwidth, and reduces power consumption due to memory reads and writes.

Q2: How does Intel DDIO relate to Intel Integrated I/O and PCI Express* 3.0?
A2: Integrated I/O is the new Intel Xeon processor E5 I/O architecture in which the PCI Express interface is integrated onto the processor itself rather than an I/O hub or south bridge. The Intel Xeon processor E5 Integrated I/O implements the PCI Express 3.0 specification and also incorporates Intel DDIO.

Q3: What applications benefit from Intel DDIO?
A3: Applications that reach, or nearly reach, the I/O bandwidth, as is common in telecomm, can have a 2x or more increase with Intel Xeon processor E5-based servers over the previous Intel Xeon processor 5600-based architecture because memory bandwidth is now no longer a constraint. With more common data center applications that do not reach the I/O bandwidth, the performance benefit will be relatively minor in general, but they will see a power consumption savings of up to seven watts per two-port NIC. Applications that are sensitive to latency, such as UDP-based financial trading, will see a reduction in latency on the order of about 10-15% due to Intel DDIO.

Read the full Intel® Data Direct I/O Frequently Asked Questions

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