On Oct 14, 2009, at 8:05 PM, Roman Shaposhnik wrote:
And how does one deal with heterogeneous cores and complex on chip
interconnect topologies?
Good question. Do they have to be heterogeneous? My oppinion is that  
the
future of big multicore will be more Cell-like.

They don't have to be, but that is part of both the multikernel and  
satellite kernel vision.
There's no real evdence that single kernels do well with hundreds of real cores (as opposed to hw threads) - in fact most of the data I've seen is to
the contrary.
Agreed. But then, again, you don't really want a kernel for anything  
but message
passing in such an architecture (the other function of the kernel --
multiplexing
I/O is only needed on selected few cores) at which point it really becomes a
misnomer to even call it a kernel -- a thin hypervisor perhaps...

If you look at the core of Barrelfish, you'll see that this is  
essentially what they are doing -- essentially using an extremely  
small microkernel (like L4) that's very
efficient at various forms of message passing.  That's the only thing  
that is duplicated on the various cores.  The services themselves can  
be distributed
and/or replicated as appropriate (although their approach favors  
replication) -- it all depends on the characteristics of the workload.
     -eric

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