Working With Code Samples

The CSL Code Examples section contains CSL programs, the .csl files, that each either demonstrate individual features of the language, or solve a larger application problem. Each program is accompanied by a Python script, the file, to run that program with the simulator.

The source for these code samples can be found inside the csl-extras-{build id}.tar.gz tarball within the release, or at the CSL examples GitHub repository (request access from

For the GEMV tutorial code samples, we additionally provide step-by-step explanations of the code in the Tutorials section.


If you’re just getting started, we recommend walking through the step-by-step tutorials in Tutorials to get a fuller explanation of these programs.

Compiling the code samples

Each code sample contains a CSL file as the top-level source file, typically named layout.csl. This file may reference additional CSL source files in that directory.

Each code sample also contains a script, which contains the commands required to compile and run the example.

For example, the tutorials/gemv-01-complete-program/ at GEMV 1: A Complete Program contains:

cslc ./layout.csl --fabric-dims=8,3 \
  --fabric-offsets=4,1 -o out --memcpy --channels 1
cs_python --name out

See also

See CSL Compiler for the compiler options documentation.

To compile the program:

  1. First cd into the directory that contains the CSL files.

  2. Then run the cslc command shown in the file to compile the program. Note, this command may span multiple lines. This command execution will produce files with the elf extension. For example:

    $ cd tutorials/gemv-01-complete-program/
    $ cslc ./layout.csl --fabric-dims=8,3 --fabric-offsets=4,1 -o out --memcpy --channels 1
    $ ls out
    bin  east  generated  out.json  west
    $ ls out/bin
    out_0_0.elf  out_rpc.json

Running the program

Use the Python script that is in the code sample directory to execute the compiled program. For example, to run the above compiled program, execute the following command in the gemv-01-complete-program directory:

$ cs_python --name out

If the program runs correctly, you will see the message SUCCESS! near the end of the output.


See Debugging Guide and SDK GUI.

Moving From Simulation To Hardware

After successfully simulating your CSL program, you can run it on hardware by following the below guidelines when using cslc:

Pass --arch flag

Use the --arch flag with cslc. This will ensure that the appropriate Cerebras system is targeted.

Allowed values are --arch=wse2 for WSE-2 architecture and --arch=wse3 for WSE-3 architecture. The default value is wse2. For example:

cslc --arch=wse2 ./layout.csl --fabric-dims=8,3 \
  --fabric-offsets=4,1 -o out --memcpy --channels 1

Note that wse3 is not yet supported for all example programs.

Provide --fabric-dims

When compiling for simulation with cslc, the --fabric-dims flag can be any bounding box large enough to contain your program’s PEs. However, when compiling for hardware, these dimensions must match your Cerebras system’s fabric dimensions. For example:

cslc --arch=wse2 ./layout.csl --fabric-dims=757,996 \
  --fabric-offsets=4,1 -o out --memcpy --channels 1

Provide IP address to SdkRuntime

To run on the Cerebras system hardware, you must pass the IP and port address of the network-attached Cerebras system to the cmaddr argument of the SdkRuntime constructor in your

runner = SdkRuntime(compile_dir, cmaddr="")