ExSystolic.Tile (ex_systolic v0.2.0)

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A rectangular partition of a systolic array.

A tile owns a subset of the array's PEs. In the partitioned backend, tiles are used to group PE executions for parallel dispatch.

BSP execution model

Each tick, the partitioned backend:

  1. Reads all link buffers globally (before any PE executes)
  2. Dispatches tile PE computations in parallel
  3. Collects results and writes outputs into links

The tile itself is just a grouping mechanism -- it carries a subset of PE states and coordinates. The actual link I/O is managed centrally by the backend.

Structure

  • :id -- unique identifier (typically {row_start, col_start})
  • :coords -- list of PE coordinates owned by this tile
  • :pes -- map of coord => {module, state}
  • :links -- list of Link.t() internal to this tile (i.e. both endpoints lie within :coords). Currently unused by the centralized-link backend, retained as documentation for future tile-local optimization.

Invariants

  • coord_set = MapSet.new(coords) == MapSet.new(Map.keys(pes))
  • Every link in :links has both from and to coords in coord_set.

Example

iex> alias ExSystolic.{PE.MAC, Tile}
iex> tile = %Tile{
...>   id: {0, 0},
...>   coords: [{0, 0}, {0, 1}],
...>   pes: %{{0, 0} => {MAC, 0}, {0, 1} => {MAC, 0}},
...>   links: []
...> }
iex> tile.id
{0, 0}

Summary

Types

id()
t()

Types

id()

@type id() :: term()

t()

@type t() :: %ExSystolic.Tile{
  coords: [ExSystolic.Grid.coord()],
  id: id(),
  links: [ExSystolic.Link.t()],
  pes: %{required(ExSystolic.Grid.coord()) => {module(), ExSystolic.PE.state()}}
}