Definitions
===========

.. glossary::

  Action
    An action is something performed by a hardware unit. For example, a read or a compute.

  Architecture
    An architecture is the hardware that is running the workload. It describes the
    components that are available and how they are connected.

  Component
    A component is a hardware unit in the architecture. For example, a memory or a compute
    unit.

  Dataflow
    The order in which a mappings iterates over tiles, noting that :term:`tiles<Tile>`
    may be abstract before the mapping is fully defined.

  Dataplacement
    Which tile(s) are stored in each memory level of the accelerator, and for what time
    period, noting that :term:`tiles<Tile>` and time periods may be abstract before the
    mapping is fully defined.

  Einsum
    An Einsum is a computation step that executes using tensors. It includes two
    operations; map, which which is performed on combinations of values from its input
    tensors, and reduce, which combines mapped values into outputs. For example, a
    matrix multiplication Einsum uses a multiply operation for the map and a sum
    operation for the reduce.

  Mapping
    A *mapping* is a schedule that maps operations and data movement onto the hardware.

  Loop
    A loop is a bounded iteration over a rank variable with a given shape and/or
    pattern. Loops in AccelForge are the for loops in mappings.

  Pmapping
    A *partial mapping*, or *pmapping*, is a :term:`Mapping` of a subset of the workload
    to the hardware.

  Pmapping Template
    A *pmapping template* is a template for a pmapping. It includes all storage nodes
    (dataplacement) and loop nodes (dataflow), but does not have loop bounds defined
    (tile shapes).

  Rank
    A rank is a dimension of a tensor.

  Reuse
    Reuse occurs when a piece of data is used used in multiple computations, but fetched
    fewer times from some memory. For example, we may fetch a piece of data from DRAM to
    on-chip memory once, then use it in ten computations. This would incur nine reuses
    of the piece of data.

  Reuse Opportunity
    Reuse opportunity is when a piece of data is used multiple times by the workload. It
    may or may not be turned into reuse if the hardware successfully leverages it.

  Tensor
    A tensor is a multi-dimensional array of data. Tensors are produced and consumed by
    :term:`Einsums<Einsum>`. A tensor's shape is parameterized by its
    :term:`ranks<Rank>`.

  Tile
    A subset of a tensor or operation space that is accessed by a set of
    :term:`loops<Loop>` in the mapping. If the loops are paratmeterized by variables for
    their bounds, then tile shapes are abstract.

  Workload
    A workload is a cascade of :term:`Einsums<Einsum>` that are executed by the
    architecture. :term:`Einsums<Einsum>` produce and consume :term:`tensors<Tensor>`,
    which are exchanged between one another.