[PATCH -rebased 00/15] Add a deadline server for sched_ext tasks

[Joel Fernandes <joelagnelf@nvidia.com>]

Just rebased on Linus's master and made adjustments. These patches have been
complete for some time without any issues. I am hoping they are merged for 6.18.

sched_ext tasks currently are starved by RT hoggers especially since RT
throttling was replaced by deadline servers to boost only CFS tasks. Several
users in the community have reported issues with RT stalling sched_ext tasks.
Add a sched_ext deadline server as well so that sched_ext tasks are also
boosted and do not suffer starvation.

2 kselftest are provided to verify the starvation fixes and bandwidth
allocation is looking correct.

Previous series:
https://lore.kernel.org/all/20250702232944.3221001-1-joelagnelf@nvidia.com/

Andrea Righi (4):
  sched/deadline: Add support to remove DL server's bandwidth
    contribution
  sched/deadline: Account ext server bandwidth
  sched/deadline: Allow to initialize DL server when needed
  selftests/sched_ext: Add test for sched_ext dl_server

Joel Fernandes (11):
  sched/debug: Fix updating of ppos on server write ops
  sched/debug: Stop and start server based on if it was active
  sched/deadline: Clear the defer params
  sched/deadline: Return EBUSY if dl_bw_cpus is zero
  sched: Add support to pick functions to take rf
  sched: Add a server arg to dl_server_update_idle_time()
  sched_ext: Add a DL server for sched_ext tasks
  sched/debug: Add support to change sched_ext server params
  sched_ext: Selectively enable ext and fair DL servers
  sched/deadline: Fix DL server crash in inactive_timer callback
  selftests/sched_ext: Add test for DL server total_bw consistency

 include/linux/sched.h                         |   2 +-
 kernel/sched/core.c                           |  19 +-
 kernel/sched/deadline.c                       | 144 +++++++--
 kernel/sched/debug.c                          | 161 ++++++++--
 kernel/sched/ext.c                            | 161 +++++++++-
 kernel/sched/fair.c                           |  15 +-
 kernel/sched/idle.c                           |   4 +-
 kernel/sched/rt.c                             |   2 +-
 kernel/sched/sched.h                          |  17 +-
 kernel/sched/stop_task.c                      |   2 +-
 kernel/sched/topology.c                       |   5 +
 tools/testing/selftests/sched_ext/Makefile    |   2 +
 .../selftests/sched_ext/rt_stall.bpf.c        |  23 ++
 tools/testing/selftests/sched_ext/rt_stall.c  | 213 +++++++++++++
 tools/testing/selftests/sched_ext/total_bw.c  | 282 ++++++++++++++++++
 15 files changed, 955 insertions(+), 97 deletions(-)
 create mode 100644 tools/testing/selftests/sched_ext/rt_stall.bpf.c
 create mode 100644 tools/testing/selftests/sched_ext/rt_stall.c
 create mode 100644 tools/testing/selftests/sched_ext/total_bw.c

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2.34.1