> I would like to set-up a CMP with private L1 caches
> and shared L2. How do I set up a network to reflect
> this ?
>
All the CMP protocols included with GEMS release 1.1 use private L1 caches
and a shared L2. The network will determine how they are connected
together.
> GEMS does not provide a bus based broadcast network
> but a crossbar based broadcast. Why ?
>
Because the GEMS network code was designed to model packet-switched
networks of any topology. We model an ordered interconnect by using a
hierarchical switch with the root node providing the ordering.
> What kind of issues will arise from using a broadcast
> switch in-lieu of a bus. Can I simulate a bus with
> GEMS.
>
You can implement a bus if you want. Its been done in Ruby before.
The HIERARCHICAL_SWITCH provides ordering, but the interconnect is not
globally atomic. Another request from a different processor may reach the
root switch first. You must handle this in your protocol. MOSI_SMP_bcast
handles these situations.
--Mike
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