Congestion leads to a severe performance degradation in multiprocessor interconnection networks. Therefore, the use of techniques
that prevent network saturation are of crucial importance to avoid high execution times.
In this paper, we propose a new mechanism that uses only local information to avoid network saturation in wormhole networks.
In order to detect congestion, each network node computes the quotient between the real transmission time of messages and
its minimum theoretical value. If this ratio is greater than a threshold, the physical channel used by the message is considered
congested. Depending on the number of congested channels, the available bandwidth to inject messages is reduced.
The main contributions of the new mechanism are three: i) it can detect congestion in a remote way, but without transmitting
control information through the network; ii) it tries to dynamically adjust the effective injection bandwidth available at
each node; and iii) it is starvation-free.
Evaluation results show that the proposed mechanism avoids network performance degradation for different network loads and
topologies. Indeed, the mechanism does not introduce any penalty for low and medium network loads, where no congestion control
mechanism is required.
This work was supported by the Spanish CICYT under Grants TIC2000-1151-C07 and 1FD97-2129