CoefficientBuffer: Maximum memory size and bandwidth on marathon frame grabbers

Operator CoefficientBuffer will not use the maximum available DRAM bandwidth and memory size of the frame grabber platform in each configuration. I made a list of configurations and measured the corresponding bandwidth in hardware:

*) Limited by Link configuration, not by DRAM

Green = possible maximum obtained

The size is valid for one operator. If you combine more operators you can use larger memory sizes.

The bandwidh represents the speed of one operator. The operator will always use the maximum bandwith of the hardware. So if the bandwidth is not equal to the maximum of the platform the operator "wastes" the bandwidth. Other DRAM operators cannot use the unused bandwidth.

There is one exception: If the link limits the bandwidth there is some bandwidth left for other operators.

In most cases you need only a single at maximum speed. As you can see from the table above, the bandwidth is limited with a single link. So you need to use multiple links and cobine the data into a single link. The coefficient data needs to be distributed over multiple files in this case. Depending on the way you combine the links (operators MergePixel, MergeParallel, InsertLine) the memory layout will difer.

The following screenshot shows a very simple link combination.

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Check out the VisualApplets documentation for memory configurations of the specific grabbers. LINK

Hi Theo

Quote from Theo

So my main question is why is the Bit Width not a part of the table above? Would you still think I should use more than one link?

The table already assumes a bit width of 64 to get to those values. I need to add more details to the post.

I know the operator does not perform very well. Thank you for the feedback. I will forward it.

Tip: It is difficult to prepare the CoefficientBuffer input files if you are using multiple links. If you don't want to write a software for testing you can use the VisualApplets simulation to generate the coefficient files.

An alternative to CoefficientBuffer is RamLUT.

Johannes