RandomSeed

#include <poplar/RandomSeed.hpp>
namespace poplar

Poplar classes and functions.

A VectorList is a list of vectors with a specific layout and with the usage semantics of a 2D vector.

A 1D vector must be laid out in a contiguous memory region. A 2D vector is a vector of 1D vectors. Each of these 1D vectors that make up a 2D vector is called a “sub-vector” for the remainder of this document. The elements of a 2D vector can be accessed by indexing the 2D vector along the outer and inner dimensions as A[outer][inner].

The following two categories of layouts are supported:

  1. VectorListLayout::DELTANELEMENTS is a memory efficient 2D vector layout. For legacy systems VectorListLayout::DELTAN served a similar purpose. Each sub-vector must be laid out as a contiguous memory region but the sub-vectors may may not be laid out contiguous with respect to each other in memory. Each sub-vector may have a different length.

  2. VectorListLayout::ONE_PTR and other VectorListLayout layouts that are prefixed by SCALED_PTR are for Poplar runtime use only.

Functions

Tensor getHwSeeds(Graph &graph, program::Sequence &prog, const DebugContext &debugContext = {})

Gets a snapshot of the h/w seeds for each worker in device.

Parameters

  • graph – The Poplar graph.

  • prog – The program sequence to be extended.

  • debugPrefix – The prefix prepended to debugging info.

Returns

A tensor of shape {number of tiles, number of worker contexts, 4}, containing seed values for each of the 4 PRNG_x_y registers for each worker context on each tile.

void setHwSeeds(Graph &graph, const Tensor &hwSeeds, program::Sequence &prog, const DebugContext &debugContext = {})

Sets the hw seeds for each worker in a device from a snapshot of the seeds.

Parameters

  • graph – The Poplar graph.

  • hwSeeds – A tensor of shape {number of tiles, number of worker contexts, 4} containing seed values for each of the 4 PRNG_x_y registers for each worker context on each tile.

  • prog – The program sequence to be extended.

  • debugPrefix – The prefix prepended to debugging info.