UCX Programming Interface for Remote Function Injection and Invocation

Abstract: Network library APIs have historically been developed with the emphasis on data movement, placement, and communication semantics. Many communication semantics are available across a large variety of network libraries, such as send-receive, data streaming, put/get/atomic, RPC, active messages, collective communication, etc. In this work we introduce new compute and data movement APIs that overcome the constraints of the single-program, multiple-data (SPMD) programming model by allowing users to send binary executable code between processing elements. Our proof-of-concept implementation of the API is based on the UCX communication framework and leverages the RDMA network for fast compute migration. We envision the API being used to dispatch user functions from a host CPU to a SmartNIC (DPU), computational storage drive (CSD), or remote servers. In addition, the API can be used by large-scale irregular applications (such as semantic graph analysis), composed of many coordinating tasks operating on a data set so big that it has to be stored on many physical devices. In such cases, it may be more efficient to dynamically choose where code runs as the applications progresses.