9. Graphcore Communication Library (GCL)

The Graphcore Communication Library (GCL) enables high-performance scale-out for IPU systems. GCL utilises the IPU’s built-in hardware support for transferring data directly from the the memory of one IPU to another via the IPU-Fabric. The result is a low-overhead, high-throughput communication library, specifically targeted at systems such as the Pod₁₂₈.

The GCL library is used by other frameworks, such as TensorFlow, to implement functions such as data-parallel gradient reductions using all-reduce.

More information about the library can be found in GCL User Guide and API Reference.