Maintain a pool of RX->TX NBLs instead of using NDIS #140
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csujedihy
reviewed
Jan 27, 2023
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| if (RxQueue->TxCloneNblList != NULL) { | ||
| TxNbl = RxQueue->TxCloneNblList; |
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Do we need to nullify the Next field on TxNbl?
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We shouldn't need to, because NdisAppendSingleNblToNblCountedQueue below automatically NULLs the Next field, and the error cases also overwrite the Next field. It might be a good idea to NULL it, but many of our NBL routines are explicitly single-NBL and therefore Next is required to be ignored.
csujedihy
approved these changes
Jan 27, 2023
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The NDIS routines that allocate and free NBLs are not very efficient for our use case: most importantly they do not support batching, and they are also just complex.
Instead, use a per-RX-queue list (which can pop a single NBL without any synchronization) and a per-RX-queue s-list (which can push/pop a batch of NBLs in a single interlocked operation) to minimize forwarding overhead.
Increases XDPMP throughput to 350Gbps from 230Gbps on a 4-CPU test machine with 1514-byte frames.