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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. Link to v1: https://lore.kernel.org/all/20250315022158.2354454-1-joelagnelf@nvidia.com/ Changes in v2: - Fixed a hang related to using rq_lock instead of rq_lock_irqsave. - Added support to remove BW of DL servers when they are switched to/from EXT. Andrea Righi (1): selftests/sched_ext: Add test for sched_ext dl_server Joel Fernandes (9): 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 the defer params sched/deadline: Add support to remove DL server bandwidth sched/ext: Relinquish DL server reservations when not needed include/linux/sched.h | 2 +- kernel/sched/core.c | 19 +- kernel/sched/deadline.c | 85 +++++-- kernel/sched/debug.c | 96 ++++---- kernel/sched/ext.c | 108 ++++++++- kernel/sched/fair.c | 15 +- kernel/sched/idle.c | 4 +- kernel/sched/rt.c | 2 +- kernel/sched/sched.h | 13 +- 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, 502 insertions(+), 81 deletions(-) create mode 100644 tools/testing/selftests/sched_ext/rt_stall.bpf.c create mode 100644 tools/testing/selftests/sched_ext/rt_stall.c CC: Joel Fernandes joelagnelf@nvidia.com CC: Ingo Molnar mingo@redhat.com CC: Peter Zijlstra peterz@infradead.org CC: Juri Lelli juri.lelli@redhat.com CC: Vincent Guittot vincent.guittot@linaro.org CC: Dietmar Eggemann dietmar.eggemann@arm.com CC: Steven Rostedt rostedt@goodmis.org CC: Ben Segall bsegall@google.com CC: Mel Gorman mgorman@suse.de CC: Valentin Schneider vschneid@redhat.com CC: Tejun Heo tj@kernel.org CC: David Vernet void@manifault.com CC: Andrea Righi arighi@nvidia.com CC: Changwoo Min changwoo@igalia.com -- 2.43.0