PCIe Deep Dive, Part 5: Flow Control

In Part 2 , I described PCIe as a bi-directional memory bus extension and looked at some factors that contribute to the efficiency of the link. A PCIe 3.0 x4 link, with 8GT/s on each lane and an efficiency of around 90%, can support bidirectional data transfer of around 3.6GB/s. But this assumes both sides of the link can consume data that quickly. In reality, a PCIe function is subject to other…