In a system where transactions are accelerated with asynchronous writes that require acknowledgements, with pre-acknowledging writes at a source of the writes, a destination-side transaction accelerator includes a queue for queue writes to a destination, at least some of the writes being pre-acknowledged by a source-side transaction accelerator prior to the write completing at the destination, a memory for storing a status of a destination-side queue and possibly other determinants, and logic for signaling to the source-side transaction accelerator with instructions to alter pre-acknowledgement rules to hold off on and pursue pre-acknowledgements based on the destination-side queue status. The rules can take into account adjusting the flow of pre-acknowledged requests or pre-acknowledgements at the sender-side transaction accelerator based at least on the computed logical length.