A Multi-Credit Flow Control scheme for asynchronous NoCs

Credit schemes are used to establish flow control in NoCs without blocking the communication channel. In traditional implementations one credit is transmitted per data flit, so the credit channel conveys as many messages as the data channel. Our proposed multi-credit scheme transmits credits in bundles of M, yielding one credit transmission per M flits. This saves transitions on the credit channel and promises a slower, more energy efficient implementation. We investigate requirements, options and benefits of this approach; first in theory, and then in a concrete application example, in which we propose a specifically beneficial implementation. Our study confirms that, with a negligible increase in area, our scheme can reduce dynamic energy as well as bandwidth requirements for the credit channel.