Transmit and receive contexts
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Transmit and Receive Contexts. Sean Hefty. Local Queue Management. Traditional view Fixed number of entries Each entry a fixed size. Memory optimized Fixed allocation Entries variable size. Local Queue Data. Application request Specified operation 0 or more IO vectors (SGEs).

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Transmit and Receive Contexts

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Transmit and receive contexts

Transmit and Receive Contexts

Sean Hefty


Local queue management

Local Queue Management

  • Traditional view

    • Fixed number of entries

    • Each entry a fixed size

  • Memory optimized

    • Fixed allocation

    • Entries variable size

www.openfabrics.org


Local queue data

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


Local queue data1

Local Queue Data

Size to record operation

Size to record IO vector

Max IOVs

Size in bytes

Alignment restriction

www.openfabrics.org


Local queue management1

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


Local queue management2

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


Injected inline data

Injected (inline) Data

  • Queue attribute

    • Maximum injected data size

  • Queue space calculation

    needed = op_size + inject_size

    • (Subject to alignment)

www.openfabrics.org


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