kernel/linux.git/tools/sched_ext/include, branch v6.18.21

tools/sched_ext: Add compat helper for scx_bpf_cpu_curr()

2025-09-04T06:40:45+00:00

Introduce a compatibility helper that allows BPF schedulers to use scx_bpf_cpu_curr() on older kernels. Fixes: 20b158094a1ad ("sched_ext: Introduce scx_bpf_cpu_curr()") Cc: Christian Loehle Signed-off-by: Andrea Righi Signed-off-by: Tejun Heo

sched_ext: Introduce scx_bpf_cpu_curr()

2025-09-03T21:50:42+00:00

Provide scx_bpf_cpu_curr() as a way for scx schedulers to check the curr task of a remote rq without assuming its lock is held. Many scx schedulers make use of scx_bpf_cpu_rq() to check a remote curr (e.g. to see if it should be preempted). This is problematic because scx_bpf_cpu_rq() provides access to all fields of struct rq, most of which aren't safe to use without holding the associated rq lock. Signed-off-by: Christian Loehle Acked-by: Andrea Righi Signed-off-by: Tejun Heo

sched_ext: Introduce scx_bpf_locked_rq()

2025-09-03T21:50:36+00:00

Most fields in scx_bpf_cpu_rq() assume that its rq_lock is held. Furthermore they become meaningless without rq lock, too. Make a safer version of scx_bpf_cpu_rq() that only returns a rq if we hold rq lock of that rq. Also mark the new scx_bpf_locked_rq() as returning NULL as scx_bpf_cpu_rq() should've been too. Signed-off-by: Christian Loehle Acked-by: Andrea Righi Signed-off-by: Tejun Heo

tools/sched_ext: Receive updates from SCX repo

2025-08-11T18:21:57+00:00

Receive tools/sched_ext updates form https://github.com/sched-ext/scx to sync userspace bits: - basic BPF arena allocator abstractions, - additional process flags definitions, - fixed is_migration_disabled() helper, - separate out user_exit_info BPF and user space code. This also fixes the following warning when building the selftests: tools/sched_ext/include/scx/common.bpf.h:550:9: warning: 'likely' macro redefined [-Wmacro-redefined] 550 | #define likely(x) __builtin_expect(!!(x), 1) | ^ Co-developed-by: Cheng-Yang Chou Signed-off-by: Andrea Righi Signed-off-by: Tejun Heo

sched_ext: idle: Introduce scx_bpf_select_cpu_and()

2025-04-07T17:13:52+00:00

Provide a new kfunc, scx_bpf_select_cpu_and(), that can be used to apply the built-in idle CPU selection policy to a subset of allowed CPU. This new helper is basically an extension of scx_bpf_select_cpu_dfl(). However, when an idle CPU can't be found, it returns a negative value instead of @prev_cpu, aligning its behavior more closely with scx_bpf_pick_idle_cpu(). It also accepts %SCX_PICK_IDLE_* flags, which can be used to enforce strict selection to @prev_cpu's node (%SCX_PICK_IDLE_IN_NODE), or to request only a full-idle SMT core (%SCX_PICK_IDLE_CORE), while applying the built-in selection logic. With this helper, BPF schedulers can apply the built-in idle CPU selection policy restricted to any arbitrary subset of CPUs. Example usage ============= Possible usage in ops.select_cpu(): s32 BPF_STRUCT_OPS(foo_select_cpu, struct task_struct *p, s32 prev_cpu, u64 wake_flags) { const struct cpumask *cpus = task_allowed_cpus(p) ?: p->cpus_ptr; s32 cpu; cpu = scx_bpf_select_cpu_and(p, prev_cpu, wake_flags, cpus, 0); if (cpu >= 0) { scx_bpf_dsq_insert(p, SCX_DSQ_LOCAL, SCX_SLICE_DFL, 0); return cpu; } return prev_cpu; } Results ======= Load distribution on a 4 sockets, 4 cores per socket system, simulated using virtme-ng, running a modified version of scx_bpfland that uses scx_bpf_select_cpu_and() with 0xff00 as the allowed subset of CPUs: $ vng --cpu 16,sockets=4,cores=4,threads=1 ... $ stress-ng -c 16 ... $ htop ... 0[ 0.0%] 8[||||||||||||||||||||||||100.0%] 1[ 0.0%] 9[||||||||||||||||||||||||100.0%] 2[ 0.0%] 10[||||||||||||||||||||||||100.0%] 3[ 0.0%] 11[||||||||||||||||||||||||100.0%] 4[ 0.0%] 12[||||||||||||||||||||||||100.0%] 5[ 0.0%] 13[||||||||||||||||||||||||100.0%] 6[ 0.0%] 14[||||||||||||||||||||||||100.0%] 7[ 0.0%] 15[||||||||||||||||||||||||100.0%] With scx_bpf_select_cpu_dfl() tasks would be distributed evenly across all the available CPUs. Signed-off-by: Andrea Righi Signed-off-by: Tejun Heo

tools/sched_ext: Sync with scx repo

2025-04-02T19:08:33+00:00

Synchronize with https://github.com/sched-ext/scx at dc44584874f0 ("kernel: Synchronize with kernel tools/sched_ext"). - READ/WRITE_ONCE() is made more proper and READA_ONCE_ARENA() is dropped. - scale_by_task_weight[_inverse]() helpers added. - Enum defs expanded to cover more and new enums. - Don't trigger fatal error when some enums are missing from kernel BTF. Signed-off-by: Tejun Heo

sched_ext: Merge branch 'for-6.14-fixes' into for-6.15

2025-03-03T18:02:22+00:00

Pull for-6.14-fixes to receive: 9360dfe4cbd6 ("sched_ext: Validate prev_cpu in scx_bpf_select_cpu_dfl()") which conflicts with: 337d1b354a29 ("sched_ext: Move built-in idle CPU selection policy to a separate file") Signed-off-by: Tejun Heo

tools/sched_ext: Provide a compatible helper for scx_bpf_events()

2025-02-27T16:26:58+00:00

Introduce __COMPAT_scx_bpf_events() to use scx_bpf_events() in a compatible way also with kernels that don't provide this kfunc. This also fixes the following error with scx_qmap when running on a kernel that does not provide scx_bpf_events(): ; scx_bpf_events(&events, sizeof(events)); @ scx_qmap.bpf.c:777 318: (b7) r2 = 72 ; R2_w=72 async_cb 319: kfunc 'scx_bpf_events' is referenced but wasn't resolved Fixes: 9865f31d852a4 ("sched_ext: Add scx_bpf_events() and scx_read_event() for BPF schedulers") Signed-off-by: Andrea Righi Signed-off-by: Tejun Heo

tools/sched_ext: Provide consistent access to scx flags

2025-02-25T18:36:36+00:00

Make all the SCX_OPS_* and SCX_PICK_IDLE_* flags available to the user-space part of the schedulers via the compat interface. This allows schedulers / selftests to set all the ops flags in user-space, rather than having them split between BPF and user-space. Signed-off-by: Andrea Righi Acked-by: Changwoo Min Signed-off-by: Tejun Heo

sched_ext: idle: Introduce scx_bpf_nr_node_ids()

2025-02-24T17:37:42+00:00

Similarly to scx_bpf_nr_cpu_ids(), introduce a new kfunc scx_bpf_nr_node_ids() to expose the maximum number of NUMA nodes in the system. BPF schedulers can use this information together with the new node-aware kfuncs, for example to create per-node DSQs, validate node IDs, etc. Signed-off-by: Andrea Righi Signed-off-by: Tejun Heo