[PATCH] sched: sync with the cfs_rq when changing sched class

[byungchul . park]

From: Byungchul Park <byungchul.park@xxxxxxx>

this work is based on a patch below, which may not be reviewed yet.

https://lkml.org/lkml/2015/8/12/914, that subject is,
"sched: sync with the prev cfs when changing cgroup within a cpu".

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