Add latency_nice priority

This patchset restarts the work about adding a latency nice priority to
describe the latency tolerance of cfs tasks.

The patches [1-4] have been done by Parth:
https://lore.kernel.org/lkml/20200228090755.22829-1-parth...

I have just rebased and moved the set of latency priority outside the
priority update. I have removed the reviewed tag because the patches
are 2 years old.

The patches [5-7] use latency nice priority to decide if a cfs task can
preempt the current running task. Patch 5 gives some tests results with
cyclictests and hackbench to highlight the benefit of latency nice
priority for short interactive task or long intensive tasks.


Change since v1:
- fix typo
- move some codes in the right patch to make bisect happy
- simplify and fixed how the weight is computed
- added support of sched core patch 7

Parth Shah (4):
  sched: Introduce latency-nice as a per-task attribute
  sched/core: Propagate parent task's latency requirements to the child
    task
  sched: Allow sched_{get,set}attr to change latency_nice of the task
  sched/core: Add permission checks for setting the latency_nice value

Vincent Guittot (3):
  sched/fair: Take into account latency nice at wakeup
  sched/fair: Add sched group latency support
  sched/core: support latency nice with sched core

 include/linux/sched.h            |   3 +
 include/uapi/linux/sched.h       |   4 +-
 include/uapi/linux/sched/types.h |  19 ++++++
 init/init_task.c                 |   1 +
 kernel/sched/core.c              |  90 ++++++++++++++++++++++++++
 kernel/sched/debug.c             |   1 +
 kernel/sched/fair.c              | 105 ++++++++++++++++++++++++++++++-
 kernel/sched/sched.h             |  34 ++++++++++
 tools/include/uapi/linux/sched.h |   4 +-
 9 files changed, 257 insertions(+), 4 deletions(-)

-- 
2.17.1