  SmartNICs are touted as an attractive substrate for network application
offloading, offering benefits in programmability, host resource saving, and
energy efficiency. The current usage restricts offloading to local hosts and
confines SmartNIC ownership to individual application teams, resulting in poor
resource efficiency and scalability. This paper presents Meili, a novel system
that realizes SmartNIC as a service to address these issues. Meili organizes
heterogeneous SmartNIC resources as a pool and offers a unified one-NIC
abstraction to application developers. This allows developers to focus solely
on the application logic while dynamically optimizing their performance needs.
Our evaluation on NVIDIA BlueField series and AMD Pensando SmartNICs
demonstrates that Meili achieves scalable single-flow throughput with a maximum
8 {\mu}s latency overhead and enhances resource efficiency by 3.07$\times$
compared to standalone deployments and 1.44$\times$ compared to
state-of-the-art microservice deployments.
