On Dec 2, 2007 8:24 AM, Jiayuan Meng <[EMAIL PROTECTED]> wrote: > > > Hi all, > > We have a mesh interconnection model and I'm thinking about refine it and > integrate it into M5. But I got several questions: > > 1. it seems the bus is tightly coupled with address mapping > (findPort(addr)). I don't understand why and how to implement the same > functionality into the mesh. I'm planning to just identify ports with their > IDs (plus a reserved ID for broadcasting). Is this okay?
For a given memory address, you need to know where the "home node" is (i.e. the memory module where that address resides, that normally responds to requests for that location). In a real bus this is done by broadcasting the request to every device and seeing which one accepts it. Our bus model uses the info from getDeviceAddressRanges() to avoid that unnecessary broadcast. > > 2. I'm not sure what the snoop ports are for. In the splash2 SE script, the > bus doesn't seem to have snoop ports. I'm confused... are you talking about the snoopPorts list in the Bus object? Not sure how that relates to the splash2 SE script. Anyway, it's just a list of normal ports that have indicated they want to snoop on coherence traffic (i.e., caches). Again, a real bus would broadcast every transaction to every device, but there's no point in sending coherence traffic to devices that don't care about snooping. > > 3. I assume the functionality of the bus/interconnection is to forward > packets from src to dst while modeling some sort of contention. Is there any > other roles this module plays? Does the bus in M5 carry any responsibilities > in coherence? Mostly the role it plays in coherence is just in making sure that all the devices that want to snoop get a chance to do so. There's also the "express snoop" functionality that was added for the new multi-level coherence scheme. Other than that it's agnostic about the coherence protocol. Steve > > Thanks! > > Jiayuan > _______________________________________________ > m5-users mailing list > m5-users@m5sim.org > http://m5sim.org/cgi-bin/mailman/listinfo/m5-users > _______________________________________________ m5-users mailing list m5-users@m5sim.org http://m5sim.org/cgi-bin/mailman/listinfo/m5-users
