Rik reported some weirdness due to the group_imb code. As a start to
looking at it, clean it up a little and add a few explanatory
comments.
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-caeeqttnla4wrrmhp5uf89gp@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>