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Department Informatik  >  Informatik 12  >  Forschung  >  ReCoNets

ReCoNets - Methodology

Methodology in a Nutshell

+ Dynamic Hardware/Software Partitioning for binding functionality to free resources at runtime
+ Hardware/Software morphing for starting and executing a function at runtime on free hardware or software resources
+ Hardware/Software migration for moving hardware bit streams or software binaries from one node to another
+ Hardware/Software checkpointing to assure that tasks do not lose important states or need to be reseted
+ Tool support for seamless integration of checkpoints into designs built with a standard design flow



The layers of the infrastructure for a reconfigurable network are shown in the Figure above. While the reconfigurable network forms the physical layer consisting of reconfigurable nodes and communication links, the top layer represents the application that will be dynamically bound on the physical layer. This binding of tasks on resources is determined by an online partitioning approach which runs in a distributed manner on the network and needs no global knowledge about the state of the network. In order to realize the online hardware/software partitioning, three main mechanisms will be applied: (1) Dynamic Rerouting, (2) Hardware/Software Task Migration and (3) Hardware/Software Morphing. Note that the dynamic rerouting becomes more complex in systems where functionality is separated from the structure of the network. While in most networks messages will be sent between nodes, a fault-tolerant and self-adaptive network demands that messages will be sent between tasks that can be hosted by different nodes. Other mechanisms for establishing a dynamic binding of tasks to nodes are the task migration and hardware/software morphing. The service provided by task migration mechanisms are required for moving tasks from one node to another while the hardware/software morphing allows for a dynamic binding of tasks to either reconfigurable hardware resources or a CPU. The task migration and morphing mechanisms require in turn an efficient hardware/software checkpointing such that states of tasks will not get lost and can be extracted and restored under real-time constraints. The Basic Network Services layer provides functions for addressing nodes, detecting link failures and sending/receiving messages. In connection with the local operating system the hardware reconfiguration management has to be considered which can be seen as the counterpart to scheduling of software tasks.

Software applications for the entire operating system infrastructure of a ReCoNet can be implemented in C++. Functions for increasing fault-tolerance and adaptability are provided by a certain API. The integration of hardware modules implemented on register transfer level will be automatically extended with checkpointing mechanisms demanded by task morphing and task migration.
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