sched/fair: Cure calc_cfs_shares() vs. reweight_entity()

Vincent reported that when running in a cgroup, his root
cfs_rq->avg.load_avg dropped to 0 on task idle.

This is because reweight_entity() will now immediately propagate the
weight change of the group entity to its cfs_rq, and as it happens,
our approxmation (5) for calc_cfs_shares() results in 0 when the group
is idle.

Avoid this by using the correct (3) as a lower bound on (5). This way
the empty cgroup will slowly decay instead of instantly drop to 0.

Reported-by: Vincent Guittot <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions