Topology aware scheduling algorithm.

[David Xu]

Jeff Roberson wrote:

> I think our identcpu.c already detects this information.  That's what 
> I'm using.  Although I assume that all cpus are identical and fall back 
> on a flat topology if this isn't the case.  I'd like to start including 
> more cache information though.
> 
> Jeff

The patch does not assume all cpus are identical, in theory, one can 
have a machine with one cpu is 4-core and another is 2-core cpu.
only one place needs to be fixed in the patch,the global variable
cpu_feature, which is easy to fix for the patch.

David Xu