CUTLASS: epilogue_workspace.h File Reference

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epilogue_workspace.h File Reference

Epilogue for threadblock scoped GEMMs. More...

`#include "cutlass/cutlass.h"`
`#include "cutlass/numeric_types.h"`
`#include "cutlass/array.h"`
Include dependency graph for epilogue_workspace.h:

Go to the source code of this file.

## Classes
class | cutlass::epilogue::EpilogueWorkspace< Shape_, WarpCount, FragmentC_ >
struct | cutlass::epilogue::EpilogueWorkspace< Shape_, WarpCount, FragmentC_ >::Params
| Parameters structure. More...
struct | cutlass::epilogue::EpilogueWorkspace< Shape_, WarpCount, FragmentC_ >::SharedStorage
| Shared storage allocation needed by the epilogue. More...

## Namespaces
| cutlass
| cutlass::epilogue

## Detailed Description

This does not attempt to target any particular output layout. Instead, each threadblock streams out its accumulator elements using 128b store operations. This assumes all threadblocks have unique output tiles.

The target data layout is:

- threadblock indices mapped to linear offsets as (m, n, k), where m is fastest-changing
- threadblock output space partitioned into warps; each warp's region is contiguous
- per-thread accumulators partitioned into 128b accesses
- output memory striped across the threads of a warp

This enables very fast streaming of data, completely limited by the memory system. No predication or data exchange is performed, and each threadblock is assumed to have a full region of memory to write to.

This epilogue establishes an upper bound for epilogue performance and is suitable for reductions across the GEMM K dimension which require a separate workspace.