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 thefuture 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 tothe contrary.Agreed. But then, again, you don't really want a kernel for anything but messagepassing in such an architecture (the other function of the kernel -- multiplexingI/O is only needed on selected few cores) at which point it really becomes amisnomer 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
