linux.git/tools/testing/selftests/sched_ext, branch master

selftests/sched_ext: Verify nohz_full tick behavior

2026-07-08T18:29:43+00:00

Finite-slice EXT tasks need the periodic scheduler tick to expire their slices even when nohz_full is enabled. Add a regression test that selects a nohz_full CPU and exercises both infinite-to-finite and finite-to-finite slice transitions across an idle interval. For each finite task, verify that its ops.tick() callback is invoked. Skip the test when an allowed nohz_full CPU and a separate housekeeping CPU are not available. Signed-off-by: Andrea Righi Signed-off-by: Tejun Heo

Merge tag 'sched_ext-for-7.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext

2026-06-17T11:10:11+00:00

Pull sched_ext updates from Tejun Heo: "Most of this continues the in-development sub-scheduler support, which lets a root BPF scheduler delegate to nested sub-schedulers. The dispatch-path building blocks landed in 7.1. A follow-up patchset in development will complete enqueue-path support for hierarchical scheduling. This cycle adds most of that infrastructure: - Topological CPU IDs (cids): a dense, topology-ordered CPU numbering where the CPUs of a core, LLC, or NUMA node form contiguous ranges, so a topology unit becomes a (start, length) slice. Raw CPU numbers are sparse and don't track topological closeness, which makes them clumsy for sharding work across sub-schedulers and awkward in BPF. - cmask: bitmaps windowed over a slice of cid space, so a sub-scheduler can track, for example, the idle cids of its shard without a full NR_CPUS cpumask. - A struct_ops variant that cid-form sub-schedulers register with, along with the cid-form kfuncs they call. - BPF arena integration, which sub-scheduler support is built on. The bpf-next additions let the kernel read and write the BPF scheduler's arena directly, turning it into a real kernel/BPF shared-memory channel. Shared state like the per-CPU cmask now lives there. - scx_qmap is reworked to exercise the new arena and cid interfaces. Additionally: - Exit-dump improvements: dump the faulting CPU first, expose the exit CPU to BPF and userspace, and normalize the dump header. - Misc kfuncs and cleanups: a task-ID lookup kfunc, __printf checking on the error and dump formatters, header reorganization, and assorted fixes" * tag 'sched_ext-for-7.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext: (59 commits) sched_ext: Add scx_arena_to_kaddr() / scx_kaddr_to_arena() sched_ext: Make scx_bpf_kick_cid() return s32 sched_ext: Add scx_cmask_test() and scx_cmask_for_each_cid() tools/sched_ext: Order single-cid cmask helpers as (cid, mask) sched_ext: Order single-cid cmask helpers as (cid, mask) selftests/sched_ext: Fix dsq_move_to_local check sched_ext: Guard BPF arena helper calls to fix 32-bit build sched_ext: idle: Fix errno loss in scx_idle_init() sched_ext: Convert ops.set_cmask() to arena-resident cmask sched_ext: Sub-allocator over kernel-claimed BPF arena pages sched_ext: Require an arena for cid-form schedulers sched_ext: Add cmask mask ops sched_ext: Track bits[] storage size in struct scx_cmask sched_ext: Rename scx_cmask.nr_bits to nr_cids tools/sched_ext: scx_qmap: Fix qa arena placement sched_ext: Mark !CONFIG_EXT_SUB_SCHED dummy stubs static inline sched_ext: Replace tryget_task_struct() with get_task_struct() sched_ext: Add scx_task_iter_relock() and use it in scx_root_enable_workfn() sched_ext: Fix ops_cid layout assert sched_ext: Use offsetofend on both sides of the ops_cid layout assert ...

Merge tag 'sched-core-2026-06-14' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip

2026-06-15T09:20:18+00:00

Pull scheduler updates from Ingo Molnar: "SMP load-balancing updates: - A large series to introduce infrastructure for cache-aware load balancing, with the goal of co-locating tasks that share data within the same Last Level Cache (LLC) domain. By improving cache locality, the scheduler can reduce cache bouncing and cache misses, ultimately improving data access efficiency. Implemented by Chen Yu and Tim Chen, based on early prototype work by Peter Zijlstra, with fixes by Jianyong Wu, Peter Zijlstra and Shrikanth Hegde. - A series to simplify CONFIG_SCHED_SMT ifdef usage (Shrikanth Hegde) Fair scheduler updates: - A series to improve SD_ASYM_CPUCAPACITY scheduling by introducing SMT awareness (Andrea Righi, K Prateek Nayak) - A series to optimize cfs_rq and sched_entity allocation for better data locality (Zecheng Li) - A preparatory series to change fair/cgroup scheduling to a single runqueue, without the final change (Peter Zijlstra) - Auto-manage ext/fair dl_server bandwidth (Andrea Righi) - Fix cpu_util runnable_avg arithmetic (Hongyan Xia) - Optimize update_tg_load_avg()'s rate-limiting code (Rik van Riel) - Allow account_cfs_rq_runtime() to throttle current hierarchy (K Prateek Nayak) - Update util_est after updating util_avg during dequeue, to fix the util signal update logic, which reduces signal noise (Vincent Guittot) Scheduler topology updates: - Allow multiple domains to claim sched_domain_shared (K Prateek Nayak) - Add parameter to split LLC (Peter Zijlstra) Core scheduler updates: - Use trace_call__() to save a static branch (Gabriele Monaco) Scheduler statistics updates: - Drop now-stale mul_u64_u64_div_u64() cputime over-approximation guard (Nicolas Pitre) Deadline scheduler updates: - Reject debugfs dl_server writes for offline CPUs (Andrea Righi) - Fix replenishment logic for non-deferred servers (Yuri Andriaccio) RT scheduling updates: - Turn RT_PUSH_IPI default off for non PREEMPT_RT (Steven Rostedt) - Update default bandwidth for real-time tasks to 1.0 (Yuri Andriaccio) Proxy scheduling updates: - A series to implement Optimized Donor Migration for Proxy Execution (John Stultz, Peter Zijlstra) - Various proxy scheduling cleanups and fixes (Peter Zijlstra, K Prateek Nayak) Misc fixes, improvements and cleanups by Aaron Lu, Andrea Righi, Zenghui Yu, Chen Yu, Guanyou.Chen, John Stultz, Shrikanth Hegde, Peter Zijlstra, Liang Luo and Yiyang Chen" * tag 'sched-core-2026-06-14' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip: (91 commits) sched/fair: Fix newidle vs core-sched sched/deadline: Use task_on_rq_migrating() helper sched/core: Combine separate 'else' and 'if' statements sched/fair: Fix cpu_util runnable_avg arithmetic sched/fair: Unify cfs_rq throttling via account_cfs_rq_runtime() sched/fair: Move the throttled tasks to a local list in tg_unthrottle_up() sched/fair: Call update_curr() before unthrottling the hierarchy sched/fair: Use throttled_csd_list for local unthrottle sched/fair: Convert cfs bandwidth throttling to use guards sched/fair: Allocate cfs_tg_state with percpu allocator sched/fair: Remove task_group->se pointer array sched/fair: Co-locate cfs_rq and sched_entity in cfs_tg_state sched: restore timer_slack_ns when resetting RT policy on fork MAINTAINERS: Fix spelling mistake in Peter's name sched: Simplify ttwu_runnable() sched/proxy: Remove superfluous clear_task_blocked_in() sched/proxy: Remove PROXY_WAKING sched/proxy: Switch proxy to use p->is_blocked sched/proxy: Only return migrate when needed sched: Be more strict about p->is_blocked ...

selftests/sched_ext: Fix dsq_move_to_local check

2026-06-01T17:17:30+00:00

scan_dsq_pool() checked == 0 against scx_bpf_dsq_move_to_local(), which returns true on success. This inverted success and failure, causing peek_dsq_dispatch() to double-dispatch on success and skip the real_dsq fallback on failure. Signed-off-by: Cheng-Yang Chou Signed-off-by: Tejun Heo

selftests/sched_ext: Validate dl_server attach/detach in total_bw test

2026-05-29T10:43:16+00:00

Extend the total_bw selftest to validate the fair/ext dl_server auto-attach/detach operations. After the existing consistency checks, the test now doubles the fair_server's runtime on every CPU via debugfs and verifies that: 1. total_bw grew after the customization (proves fair_server was attached and apply_params() honored the dl_bw_attached flag), 2. with the minimal BPF scheduler loaded, total_bw drops back to the baseline value (proves fair_server was detached and ext_server was attached at its own default runtime), 3. after unload total_bw matches the doubled value from step 1 (proves fair_server was re-attached with the runtime customization preserved across the load/unload cycle). Signed-off-by: Andrea Righi Signed-off-by: Peter Zijlstra (Intel) Acked-by: Juri Lelli Link: https://patch.msgid.link/20260526164420.638711-3-arighi@nvidia.com

Merge branch 'for-7.1-fixes' into for-7.2

2026-05-11T22:43:39+00:00

Pull to receive: 9a415cc53711 ("sched_ext: Avoid UAF in scx_root_enable_workfn() init failure path") Conflicts with for-7.2's scx_task_iter_relock() rework. The fix moves put_task_struct(p) past scx_error(); for-7.2 still has it at the old position. Resolved by dropping the old one. Signed-off-by: Tejun Heo

selftests/sched_ext: Fix build error in dequeue selftest

2026-05-11T02:03:05+00:00

Building the dequeue selftest with newer compilers (e.g., gcc 16) triggers the following error: dequeue.c:28:22: error: variable 'sum' set but not used The 'volatile' qualifier prevents the writes from being optimized away, but does not silence the unused variable 'sum' is indeed only written and never read. Consume 'sum' via an empty asm() with a register input constraint. This forces the compiler to keep the accumulated value (preserving the CPU stress loop) and avoiding the build error. Fixes: 658ad2259b3e ("selftests/sched_ext: Add test to validate ops.dequeue() semantics") Signed-off-by: Andrea Righi Signed-off-by: Tejun Heo

selftests/sched_ext: Fix select_cpu_dfl link leak on early return

2026-05-08T15:34:39+00:00

If run() exits early via SCX_EQ/SCX_ASSERT (which calls return directly), bpf_link__destroy() is never reached and the BPF scheduler stays loaded. All subsequent tests then fail to attach because SCX is not in the DISABLED state. Move bpf_link into a context struct so cleanup() always destroys it, regardless of how run() exits. Also skip waitpid() for children where fork() returned -1, avoiding waitpid(-1,...) accidentally reaping an unrelated child and triggering the early return path. Signed-off-by: Cheng-Yang Chou Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi

selftests/sched_ext: Include common.bpf.h to avoid build failure

2026-04-23T16:00:21+00:00

In scx-cid patchsets, sched_ext selftest failed to build with following error: non_scx_kfunc_deny.bpf.c:17:6: error: conflicting types for 'scx_bpf_kick_cpu' 17 | void scx_bpf_kick_cpu(s32 cpu, u64 flags) __ksym; | ^ tools/testing/selftests/sched_ext/build/include/vmlinux.h:136300:13: note: previous declaration is here 136300 | extern void scx_bpf_kick_cpu(s32 cpu, u64 flags, const struct bpf_prog_aux *aux) __weak __ksym; | ^ non_scx_kfunc_deny.bpf.c:26:23: error: too few arguments to function call, expected 3, have 2 26 | scx_bpf_kick_cpu(0, 0); | ~~~~~~~~~~~~~~~~ ^ tools/testing/selftests/sched_ext/build/include/vmlinux.h:136300:13: note: 'scx_bpf_kick_cpu' declared here 136300 | extern void scx_bpf_kick_cpu(s32 cpu, u64 flags, const struct bpf_prog_aux *aux) __weak __ksym; The root cause is on scx core part, but we can avoid this by including common.bpf.h and remove scx_bpf_kick_cpu() to make it more robust, just like the usage in other xx.bpf.c. Link: https://lore.kernel.org/sched-ext/20260421071945.3110084-1-tj@kernel.org/ Signed-off-by: Zhao Mengmeng Tested-by: Cheng-Yang Chou Signed-off-by: Tejun Heo

selftests/sched_ext: Add non_scx_kfunc_deny test

2026-04-20T17:57:29+00:00

Verify that the BPF verifier rejects a non-SCX struct_ops program (tcp_congestion_ops) that attempts to call an SCX kfunc (scx_bpf_kick_cpu). The test expects the load to fail with -EACCES from scx_kfunc_context_filter. Signed-off-by: Cheng-Yang Chou Signed-off-by: Tejun Heo