  As a momentous enabling of the Internet of things (IoT), mobile edge
computing (MEC) provides IoT mobile devices (MD) with powerful external
computing and storage resources. However, a mechanism addressing distributed
task offloading and price competition for the open exchange marketplace has not
been established properly, which has become a huge obstacle to MEC's
application in the IoT market. In this paper, we formulate a distributed
mechanism to analyze the interaction between OSPs and IoT MDs in the MEC
enabled edge-cloud system by appling multi-leader multi-follower two-tier
Stackelberg game theory. We first prove the existence of the Stackelberg
equilibrium, and then we propose two distributed algorithms, namely iterative
proximal offloading algorithm (IPOA) and iterative Stackelberg game pricing
algorithm (ISPA). The IPOA solves the follower non-cooperative game among IoT
MDs and ISPA uses backward induction to deal with the price competition among
OSPs. Experimental results show that IPOA can markedly reduce the disutility of
IoT MDs compared with other traditional task offloading schemes and the price
of anarchy is always less than 150\%. Besides, results also demonstrate that
ISPA is reliable in boosting the revenue of OSPs.
