In message <20070306144026.74DC1233C4C@mail.linija.org>,
"Mindaugas R." writes:

>jonathan@dsg.stanford.edu wrote:
>> If there's no global run queue at all, how do you rebalance across
>> CPUs? 
>It depends on scheduler implementation. There would be a sched_migrate() in
>the API, provided for "outside", but in general - all balancing would be done
>internally i.e. dispatcher would not know anything about it, thought.

I don't follow how this would work.  Can you explain how the case of,
say, 4 CPUs, 5 longterm (infinite) always-runnable CPU-bound tasks,
plus a few I/O bound threads, would work so as to give fairness across
the 5 CPU-bound processes/threads?  I'm not seeing how you would know
which processes to move, or where, or for how long, without some
global state; or (alternatively) without grabbing locks on other CPU's
internal scheduler state.  Which sounds like it could lead to deadlocks.