[RFC,0/8] Add a deadline server for sched_ext tasks

Message

Joel Fernandes March 15, 2025, 2:21 a.m. UTC

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.

A kselftest is also provided to verify the starvation issues are now fixed.

Andrea Righi (1):
  selftests/sched_ext: Add test for sched_ext dl_server

Joel Fernandes (7):
  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: Fix updating of ppos on server write ops
  sched/debug: Stop and start server based on if it was active
  sched/debug: Add support to change sched_ext server params
  sched/deadline: Clear defer params

 include/linux/sched.h                         |   2 +-
 kernel/sched/core.c                           |  19 +-
 kernel/sched/deadline.c                       |  30 +--
 kernel/sched/debug.c                          |  96 ++++----
 kernel/sched/ext.c                            |  64 +++++-
 kernel/sched/fair.c                           |  15 +-
 kernel/sched/idle.c                           |   4 +-
 kernel/sched/rt.c                             |   2 +-
 kernel/sched/sched.h                          |  12 +-
 kernel/sched/stop_task.c                      |   2 +-
 tools/testing/selftests/sched_ext/Makefile    |   1 +
 .../selftests/sched_ext/rt_stall.bpf.c        |  23 ++
 tools/testing/selftests/sched_ext/rt_stall.c  | 213 ++++++++++++++++++
 13 files changed, 406 insertions(+), 77 deletions(-)
 create mode 100644 tools/testing/selftests/sched_ext/rt_stall.bpf.c
 create mode 100644 tools/testing/selftests/sched_ext/rt_stall.c