messages in-transit from SSI communication objects

Hey,

Could you give me some hints about how the messages in-transit over the 
network from SSI communication objects are dealt with when a migration 
request arrives?

I imagine that there are two occasions when a process may receive a 
message from a communication object located on another node: either when 
the process is currently executing an I/O system call to the object or 
the object sends SIGIO asynchronously. Is that correct?

In the former case, I imagine that the system call is interrupted in the 
same manner as when a signal would arrive. There is a mechanism that 
cancels the communication procedure cleanly, is that correct? In 
particular, the request is delayed until all the RPC calls are 
finalized, and perhaps some extra RPCs calls are made to cancel the 
operation? And after the migration, some system calls would return EINTR 
and others would be re-executed from scratch?

In the latter case, how the signals are dealt with during migration: do 
they follow the migrated process or a lock prevents sending a signal to 
a migrating process? And is SIGIO the only asynchronous message that may 
be received from a remote object?

I am kind of confused, does this make sense? Am I missing something?

Thanks,
AK


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