Dual Channel RAM Performance for PXI Embedded Controllers Hardware: Compact FieldPoint>>Controllers
Problem: What is Dual Channel RAM? What do you need to take full advantage of Dual Channel RAM performance on National Instruments embedded controllers? What are the performance increase when using dual channel RAM? Solution: The memory controller controls data flow between the RAM and the processor. When using dual channel RAM, the memory controller sees 2 parallel banks of RAM which it can access at one time. In the example below, you can see that in the single channel case, the memory controller can access 64 bits from 1 bank of RAM. In the dual channel case, the memory controller can also access 128 bits using two banks. In other words, dual channel RAM is used to increase the data bandwidth between the processor and RAM. Single Channel RAM Example  Dual Channel RAM Example  There are specific guidelines that need to be followed such that the memory controller can use Dual Channel RAM effectively. For National Instruments embedded controller using Intel processors, the RAM modules must have the same size. However, it does not have to have the same speed, timing specifications or brand. Memory channel speed is determined by the slowest DIMM module populated in the system. Note: We recommend that you purchase RAM from National Instrument as it has been tested with the controllers. Off-the-shelf RAM is not guaranteed to work. It is estimated that a dual-channel memory architecture is capable of increasing bandwidth from 10 to 50 percent. If the guideline above is not followed, the processor will configure the RAM to single channel automatically. Related Links: Intel Desktop Boards: Dual/Single/Flex Mode Intel Dual-Channel DDR Memory Architecture White Paper Attachments:
Report Date: 02/19/2008 Last Updated: 02/20/2008 Document ID: 4IIHFFOH |
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