sched: retain vruntime

Kei Tokunaga reported an interactivity problem when moving tasks
between control groups.

Tasks would retain their old vruntime when moved between groups, this
can cause funny lags. Re-set the vruntime on group move to fit within
the new tree.

Reported-by: Kei Tokunaga <tokunaga.keiich@jp.fujitsu.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 5 insertions, 0 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index dcd553cc4ee8..0b949c4e73ad 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7625,6 +7625,11 @@ void sched_move_task(struct task_struct *tsk)
 
         set_task_rq(tsk, task_cpu(tsk));
 
+#ifdef CONFIG_FAIR_GROUP_SCHED
+        if (tsk->sched_class->moved_group)
+                tsk->sched_class->moved_group(tsk);
+#endif
+
         if (on_rq) {
                 if (unlikely(running))
                         tsk->sched_class->set_curr_task(rq);