I did a little study on the code of credit scheduler of xen.
I am confused on overhear of the migration of VCPU .
As I learned, the course of VCPU migration is just to return a "reasonable"
VCPU of other peer PCPU
to the PCPU which is busy on other VCPU, as well as some judgments
before(eg., comparision of VCPU priority, affintiy).
In a word, it is just a pointer returned.
My question is where is the overhead,
or the overhead of executing those load_balance codes is expensive,
or will the migration of VCPU introducing the somekind of cache