Emulex Design & Manufacturing Corporation

Emulex Corporation

Sam Shan-Jan Su

Peter Mark Fiacco

Vuong Cao Nguyen

John Sui-kei Tang

Daming Jin

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.

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Costa Mesa, CA, United States of America

Sam Shan-Jan Su