Restore PCIe transaction ID on the fly

摘要

Restoring retired transaction identifiers (TID) associated with Direct Memory Access (DMA) commands without waiting for all DMA traffic to terminate is disclosed. A scoreboard is used to track retired TIDs and selectively restore retired TIDs on the fly. DMA engines fetch a TID, and use it to tag every DMA request. If the request is completed, the TID can be recycled to be used to tag a subsequent request. However, if a request is not completed, the TID is retired. Retired TIDs can be restored without having to wait for DMA traffic to end. Any retired TID value may be mapped to a bit location inside a scoreboard. All processors in the system may have access to read and clear the scoreboard. Clearing the TID scoreboard may trigger a DMA engine to restore the TID mapped to that location, and the TID may be used again.

主权项

1. A system for managing retired transaction identifiers (TIDs), the system comprising:
a memory operable to maintain an individual status of each TID of a plurality of TIDs, the plurality of TIDs comprising one or more retired TIDs, wherein a TID is retired if an associated command does not complete; and a processor operable to selectively restore a first retired TID of the one or more retired TIDs, wherein the first retired TID is selectively restored without requiring the processor to be reset.