  With the development of networking technology, the computing system has
evolved towards the multi-tier paradigm gradually. However, challenges, such as
multi-resource heterogeneity of devices, resource competition of services, and
networked system dynamics, make it difficult to guarantee service-level
agreement (SLA) for the applications. In this paper, we propose a multi-tier
edge-cloud computing framework, EdgeMatrix, to maximize the throughput of the
system while guaranteeing different SLA priorities. First, in order to reduce
the impact of physical resource heterogeneity, EdgeMatrix introduces the
Networked Multi-agent Actor-Critic (NMAC) algorithm to re-define physical
resources with the same quality of service as logically isolated resource units
and combinations, i.e., cells and channels. In addition, a multi-task mechanism
is designed in EdgeMatrix to solve the problem of Joint Service Orchestration
and Request Dispatch (JSORD) for matching the requests and services, which can
significantly reduce the optimization runtime. For integrating above two
algorithms, EdgeMatrix is designed with two time-scales, i.e., coordinating
services and resources at the larger time-scale, and dispatching requests at
the smaller time-scale. Realistic trace-based experiments proves that the
overall throughput of EdgeMatrix is 36.7% better than that of the closest
baseline, while the SLA priorities are guaranteed still.
