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Transmit and Receive Contexts

Transmit and Receive Contexts

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Transmit and Receive Contexts

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  1. Transmit and Receive Contexts Sean Hefty

  2. Local Queue Management • Traditional view • Fixed number of entries • Each entry a fixed size • Memory optimized • Fixed allocation • Entries variable size www.openfabrics.org

  3. Local Queue Data • Application request • Specified operation • 0 or more IO vectors (SGEs) • Provider limits • Size of transmit queue • Maximum number of IOVs www.openfabrics.org

  4. Local Queue Data Size to record operation Size to record IO vector Max IOVs Size in bytes Alignment restriction www.openfabrics.org

  5. Local Queue Management • Queue attributes • Total size, in bytes • IOV limit – max number of IOVs for a single operation • Operation alignment, in bytes • Calculate padding with each operation • Domain attributes • Operation size, in bytes • Amount of space consumed to track each request • IOV size, in bytes • Amount of space consumed for each IOV www.openfabrics.org

  6. Local Queue Management • Generic calculation done by app: needed = ((op_size + iov_size * nsge) +op_alignment- 1) & ~(op_alignment - 1) • For queues with fixed sized entries: • needed = op_alignment • For queues with variable sized entries • needed = op_size + iov_size * nsge www.openfabrics.org

  7. Injected (inline) Data • Queue attribute • Maximum injected data size • Queue space calculation needed = op_size + inject_size • (Subject to alignment) www.openfabrics.org