Re: SMP/cc Cluster description

[Larry McVoy]

On Thu, Dec 06, 2001 at 03:08:47PM -0800, David S. Miller wrote:
>    From: Benjamin LaHaise <[e-mail]>
>    Date: Thu, 6 Dec 2001 17:27:08 -0500
> 
>    	- lower overhead for SMP systems.  We can use UP kernels local 
>    	  to each CPU.  Should make kernel compiles faster. ;-)
>    
> Actually, this isn't what is being proposed.  Something like
> "4 cpu" SMP kernels.

I personally want to cluster small SMP OS images because I don't want to
do the process migration crap anywhere except at exec time, it simplifies
a lot.  So I need a second order load balancing term that I can get
from 2 or 4 way smp nodes.  If you are willing to process migration to
handle load imbalances, then you could do uniprocessor only.  I think
the complexity tradeoff is in favor of the small SMP OS clusters, we
already have them.  Process migration is a rats nest.

>    At the very least it is well worth investigating.  Bootstrapping the 
>    ccCluster work shouldn't take more than a week or so, which will let 
>    us attach some hard numbers to the kind of impact it has on purely 
>    cpu local tasks.
>    
> I think it is worth considering too, but I don't know if a week
> estimate is sane or not :-)

Yeah, it's possible that you could get something booting in a week but I
think it's a bit harder than that too.  One idea that was kicked around
was to use Jeff's UML work and "boot" multiple UML's on top of a virtual
SMP.  You get things to work there and then do a "port" to real hardware.
Kind of a cool idea if you ask me.