Dataflow Performance Issues

Explanation

In the dataflow network pictured above, the warning message reports a possible design performance problem. If you write to those FIFOs late (i.e. at the end of process P1), you are potentially throttling when process P2 can start, making the overall latency P1's plus P2's latency. The algorithm is warning you that processes P1 and P2 are potentially synchronized to the function's ap_done handshake. Instead, if you write into that FIFO early, you will not notice a performance drop because the latency ideally becomes max (P1_Lat, P2_Lat). This is somewhat design-dependent and therefore difficult for the tool to completely analyze.

Note that this warning is only relevant when the block level protocol is ap_ctrl_hs or ap_ctrl_chain.