Contents

Kernel Development Flow

Developing a kernel

Before proceeding, make sure you read the A Conceptual View section.

Scope of this section

This section does not directly discuss how to write your kernel using a CSL program. However, you should read this section to understand, at a high-level, the steps to develop a kernel with CSL. Also see CSL.

CSL code and runtime script

Developing a kernel constitutes the following:

  • Developing a CSL program, such as a <filename>.csl that defines the operations a PE or a set of PEs must perform. Often you will create multiple csl files. For example, see Multiple Source Files.

  • Compiling the top-level .csl program with the cslc compiler.

  • Running the program, either with the simulator or on the Cerebras Wafer Scale Engine (WSE), using a runtime configuration script, usually written in Python, such as code.csl.run.py. Here you will provide the input tensors to the simulator, and

  • When the simulation is complete, read the simulator output and compare against a reference for validating the program output.

Kernel development steps

The following diagrams show the sequence of steps for developing a kernel.

Step 1

_images/cslang-kernel-dev-flow1.png

In your CSL code you must explicitly:

  • Define a layout by using @set_rectangle() function. This defines a Rectangular region of contiguous processing elements (PEs).

  • For each PE, use the @set_tile_code() to define the code the PE will run.

  • Configure the routes and colors with @set_color_config().

Steps 2 and 3

_images/cslang-kernel-dev-flow2.png

  • Next, you compile the top-level code.csl with the compiler tool cslc. This will generate a binary ELF file for each PE.

  • Finally, use the runtime Python script code.csl.run.py to run the code either on the simulator or directly on the Cerebras WSE.

Note

The above flow is the same when you are targeting the actual network-attached Cerebras WSE accelerator device, except that Run step will target the network-attached CS WSE accelerator, instead of the local fabric simulator.

Example walkthrough

See Example and Working With Code Samples.

A Conceptual View CSL Compiler