Re: [Gems-users] Crossbar with SimpleNetwork

[Byn Choi <bynchoi1@xxxxxxxxxxxx>]

My belief is that your network file just duplicates what ruby would do  
internally when you specify CROSSBAR (all-to-all connection through  
single-central node).
I personally don't know if you can simulate a bus model.

On Feb 1, 2011, at 4:27 PM, Nilay Vaish wrote:

> Joseph, I think both the representations are correct. But whether  
> your representation will correctly function or not is not known to  
> me. Another thing to be noticed is that by connecting an L1 cache /  
> directory to a crossbar switch directly, we might be making some  
> assumption on what functionality a cache controller provides (over  
> here I am talking about a real cache controller). By separating the  
> external nodes and internal nodes, I think we are trying to separate  
> the routing functionality from the external nodes.
> The view I presented above is my personal understanding, so it might  
> be incorrect.
> --
> Nilay
>
>
> On Tue, 1 Feb 2011, Joseph Pusdesris wrote:
>
> > Ok, but assuming it was set to FILE_SPECIFIED and I generated the  
> > topology
> > by another means, which one would be correct?  Also, you didn't  
> > mention of a
> > bus model is feasible.
> >
> > Thanks!
> > Joseph
> >
> > On Mon, Jan 31, 2011 at 3:58 PM, Byn Choi <bynchoi1@xxxxxxxxxxxx>  
> > wrote:
> > > I don't know how M5 handles network topologies, but you'd set
> > > g_NETWORK_TOPOLOGY to CROSSBAR to use crossbar with ruby in GEMS.  
> > > The
> > > network configuration file is only relevant when you set that to
> > > FILE_SPECIFIED. By default the scripts generate a 2-D mesh network.
> > >
> > > Byn
> > >
> > > On Jan 31, 2011, at 2:48 PM, Joseph Pusdesris wrote:
> > >
> > > Hello, I am trying to generate several topologies for the M5  
> > > simulator
> > > using Ruby's SimpleNetwork and I have a few questions.  Am I  
> > > correct in
> > > assuming that the SimpleNetwork framework cannot support a bus  
> > > model without
> > > modifying the source for PerfectSwitch?
> > >
> > > I am also confused about the topologies which are included in the
> > > repository.  The default crossbar topology that is included in the  
> > > m5
> > > repository generates something along these lines:
> > >
> > > ext_node:L1Cache:0 int_node:0 link_latency:1 bw_multiplier:64
> > > ext_node:L1Cache:1 int_node:1 link_latency:1 bw_multiplier:64
> > > ext_node:L1Cache:2 int_node:2 link_latency:1 bw_multiplier:64
> > > ext_node:L1Cache:3 int_node:3 link_latency:1 bw_multiplier:64
> > > ext_node:L2Cache:0 int_node:4 link_latency:1 bw_multiplier:64
> > > ext_node:Directory:0 int_node:5 link_latency:40 bw_multiplier:10
> > >
> > > int_node:0 int_node:6 link_latency:40 bw_multiplier:16
> > > int_node:1 int_node:6 link_latency:40 bw_multiplier:16
> > > int_node:2 int_node:6 link_latency:40 bw_multiplier:16
> > > int_node:3 int_node:6 link_latency:40 bw_multiplier:16
> > > int_node:4 int_node:6 link_latency:40 bw_multiplier:16
> > > int_node:5 int_node:6 link_latency:40 bw_multiplier:16
> > >
> > > This doesn't make sense to me.  Why is there the extra level of  
> > > switches
> > > before connecting nodes to the xbar switch?  Is it an error in the
> > > repository or am I misunderstanding something?  Wouldn't a more  
> > > proper
> > > crossbar look like:
> > >
> > > ext_node:L1Cache:0 int_node:0 link_latency:1 bw_multiplier:64
> > > ext_node:L1Cache:1 int_node:0 link_latency:1 bw_multiplier:64
> > > ext_node:L1Cache:2 int_node:0 link_latency:1 bw_multiplier:64
> > > ext_node:L1Cache:3 int_node:0 link_latency:1 bw_multiplier:64
> > > ext_node:L2Cache:0 int_node:0 link_latency:1 bw_multiplier:64
> > > ext_node:Directory:0 int_node:0 link_latency:40 bw_multiplier:10
> > >
> > > -Joseph
> > > _______________________________________________
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> > >
> > >
> > > ---
> > > Byn Choi
> > > Ph.D. Candidate in Computer Science
> > > University of Illinois, Urbana-Champaign
> > >
> > >
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---
Byn Choi
Ph.D. Candidate in Computer Science
University of Illinois, Urbana-Champaign