Changes between Version 21 and Version 22 of Writing Rules/Tlmt


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Timestamp:
Dec 27, 2007, 11:10:19 AM (16 years ago)
Author:
alain
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  • Writing Rules/Tlmt

    v21 v22  
    245245= E) VCI Interconnect =
    246246
    247 The VCI interconnect used for the TLM-T simulation is a generic simulation model, named '''VciVgmn'''.
     247The VCI interconnect used for the TLM-T simulation is a generic simulation model, named '''!VciVgmn'''.
    248248The two main parameters are the number of initiators, and the number of targets. In TLM-T simulation,
    249 we don't want to reproduce the cycle-accurate behavior of a particular interconnect. We only want to simulate the contention when several VCI intitiators try to reach the same VCI target.
    250 Therefore, the network is actually modeled as a cross-bar : In a physical network such as the multi-stage network described in Figure 2.a, conflicts can appear at any intermediate switch. In the '''VciVgmn''' network described in Figure 2.b, conflicts can only happen at the output ports. It is possible to model to specify a specific latency for each input/output couple. As in most physical interconnects, the general arbitration policy is round-robin.
     249we don't want to reproduce the cycle-accurate behavior of a particular interconnect. We only want to simulate the contention in the network, when several VCI intitiators try to reach the same VCI target.
     250Therefore, the network is actually modeled as a complete cross-bar : In a physical network such as the multi-stage network described in Figure 2.a, conflicts can appear at any intermediate switch. In the '''!VciVgmn''' network described in Figure 2.b, conflicts can only happen at the output ports. It is possible to specify a specific latency for each input/output couple. As in most physical interconnects, the general arbitration policy is round-robin.
    251251
    252252[[Image(tlmt_figure_2.png, nolink)]]
    … …  
    254254== E.1) Generic network modeling ==
    255255
    256  As in most physical network on chip, there is actually two fully independent networks for command packets and response packets. There is a routing function for each input port, and an arbitration function for each output port, but the two networks are not symmetrical :
     256 There is actually two fully independent networks for VCI command packets and VCI response packets. There is a routing function for each input port, and an arbitration function for each output port, but the two networks are not symmetrical :
    257257 * For the command network, the arbitration policy is distributed: there is one arbitration thread for each output port (i.e. one arbitration thread for each VCI target). Each arbitration thread is modeled by a SC_THREAD, and contain a local clock.
    258  * For the response network, there is no conflicts, and there is no need for arbitration. Therefore, there is no thread (and no local time) in the response network that is implemented by simple function calls.
     258 * For the response network, there is no conflicts, and there is no need for arbitration. Therefore, there is no thread (and no local time) and the response network is implemented by simple function calls.
    259259
    260260This is illustrated in Figure 3 for a network with 2 initiators and three targets :