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Re: [charm] Question about BigNetSim


Chronological Thread 
  • From: Eric Bohm <ebohm AT illinois.edu>
  • To: charm AT cs.uiuc.edu, xxhdx1985126 AT gmail.com
  • Subject: Re: [charm] Question about BigNetSim
  • Date: Fri, 21 Oct 2011 13:48:57 -0500
  • List-archive: <http://lists.cs.uiuc.edu/pipermail/charm>
  • List-id: CHARM parallel programming system <charm.cs.uiuc.edu>

Your modification would appear to violate the consensus reality of the simulation. How would a NIC communicate with another NIC without consuming the bandwidth of a channel? Such NIC to NIC telepathy is non-physical.

If you are introducing some entirely new communication mode, then it should be embodied in a new simulation entity. You are not sending a packet over a channel, so don't use the existing recvPacket event method which is designed to implement packet reception, and acknowledgement, via a channel. Add your own event method which implements the operation you are creating.


On 10/21/2011 01:27 PM, Xuehan Xu wrote:
Dear Sirs:
I made some modification to the BlueGene network model, I wish
some of the NetInterfaces in the network model to communicate with each
other directly, not through channels or switches. So, in the
NetInterface class, I insert the statement "POSE_invoke(recvPacket(p),
NetInterface, DestId, Delay)" to let the NetInterfaces to communicate
with each other directly when some condition is satisfied. But, it seems
that every time this POSE_invoke is made, the recvPacket of the
NetInterface on the other side will try to call the "buildAck()"
function which is only called when the multicast is available and lead
to a segmentation fault. When I delete these POSE_invokes, the problem
no longer exists, and the buildAck is never called at all.

The problem can be duplicated by replacing the POSE_invoke call
to switch at Nic.C line 186 with a POSE_invoke call to some NetInterface
object in the network model.

Why is this happenning? I'm so confused, please help me. Thanks
everyone:-)



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