sched: Improve convergence

sched: Improve convergence

 - break out of can_do_numa_run() earlier if we can make no progress
 - don't flip between siblings that often
 - turn on bidirectional fault balancing
 - improve the flow in task_numa_work()

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>