Mapper and Router Options - 2021.2 English

Versal ACAP AI Engine Programming Environment User Guide (UG1076)

Document ID
UG1076
ft:locale
English (United States)
Release Date
2021-12-17
Version
2021.2 English
Table 1. Mapper Options
Options Description
DisableFloorplanning This option disables the auto-floor-planning phase in the mapper. This option is useful for heavily constrained designs where you want to guide mapping phase by using location constraints.
BufferOptLevel[1-9] These options can be used to improve throughput by reducing memory bank conflicts. At higher BufferOptLevel, mapper tries to reduce number of buffers getting mapped into same memory bank, thereby reducing the probability of bank conflicts affecting overall performance. Higher BufferOptLevels can increase the size of the overall mapped region, and in few cases, can fail to find a solution. The default of BufferOptLevels is BufferOptLevel0.
disableSeparateTraceSolve Default trace behavior forces the AI Engine mapper to keep all PLIOs/GMIOs in the original design location when using the trace debug feature. However, if the original solution did not leave any room for trace GMIOs, no solution will be possible unless the design PLIOs are moved. This option is to be used in this case.
Note: You can recirculate the previous design placement in your next compilation. This significantly reduces the mapper run time. When the compiler runs, it generates a placement constraints file, graph_aie_mapped.aiecst, in the Work/temp directory. Xilinx recommends that you save Work/temp/graph_aie_mapped.aiecst if you want to use it in subsequent compilations because the Work folder is regenerated for every compilation. This constraint file can be specified on the command line for the next iteration.
aiecompiler --constraints Work/temp/graph_aie_mapped.aiecst src/graph.cpp
Tip: The mapper is not aware of the 16K program memory per core limitation. One workaround is to change the run-time usage specification to map kernels to different cores.
Table 2. Router Options
Options Description
enableSplitAsBroadcast This option treats all split nets from a split node as a single net, with 100% usage broadcasting to multiple points. This broadcast net does not share resources with any other packet switched net in the design. This option can be used when throughput degradation is observed due to interference on packetstream nets after split node.
dmaFIFOsInFreeBankOnly This option ensures DMA FIFOs are only inserted into memory banks that have no other buffers mapped. This option can be used when memory stalls are observed due to DMA FIFO buffers being accessed at the same time as some other design buffer placed in the same bank.
disableSSFifoSharing Disables the ability of the router to share stream switch FIFOs among two or more terminals of a net. This option should only be used when there are not enough stream switch FIFOs in the device to give each terminal its own individual FIFO(s).