1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES
4 *
5 * Exercise tick dependency transitions between infinite and finite slices.
6 */
7 #include <scx/common.bpf.h>
8
9 char _license[] SEC("license") = "GPL";
10
11 const volatile s32 test_cpu;
12 bool finite_phase;
13 u64 nr_inf_running;
14 u64 nr_finite_running;
15 u64 nr_finite_ticks;
16
17 UEI_DEFINE(uei);
18
BPF_STRUCT_OPS(nohz_tick_select_cpu,struct task_struct * p,s32 prev_cpu,u64 wake_flags)19 s32 BPF_STRUCT_OPS(nohz_tick_select_cpu, struct task_struct *p, s32 prev_cpu,
20 u64 wake_flags)
21 {
22 return prev_cpu;
23 }
24
BPF_STRUCT_OPS(nohz_tick_enqueue,struct task_struct * p,u64 enq_flags)25 void BPF_STRUCT_OPS(nohz_tick_enqueue, struct task_struct *p, u64 enq_flags)
26 {
27 u64 slice = finite_phase ? 1000000ULL : SCX_SLICE_INF;
28
29 scx_bpf_dsq_insert(p, SCX_DSQ_GLOBAL, slice, enq_flags);
30 if (enq_flags & SCX_ENQ_LAST)
31 scx_bpf_kick_cpu(test_cpu, SCX_KICK_IDLE);
32 }
33
BPF_STRUCT_OPS(nohz_tick_running,struct task_struct * p)34 void BPF_STRUCT_OPS(nohz_tick_running, struct task_struct *p)
35 {
36 if (bpf_get_smp_processor_id() != test_cpu)
37 return;
38
39 if (finite_phase)
40 __sync_fetch_and_add(&nr_finite_running, 1);
41 else
42 __sync_fetch_and_add(&nr_inf_running, 1);
43 }
44
BPF_STRUCT_OPS(nohz_tick_tick,struct task_struct * p)45 void BPF_STRUCT_OPS(nohz_tick_tick, struct task_struct *p)
46 {
47 if (bpf_get_smp_processor_id() == test_cpu && finite_phase)
48 __sync_fetch_and_add(&nr_finite_ticks, 1);
49 }
50
BPF_STRUCT_OPS(nohz_tick_exit,struct scx_exit_info * ei)51 void BPF_STRUCT_OPS(nohz_tick_exit, struct scx_exit_info *ei)
52 {
53 UEI_RECORD(uei, ei);
54 }
55
56 SEC(".struct_ops.link")
57 struct sched_ext_ops nohz_tick_ops = {
58 .select_cpu = (void *)nohz_tick_select_cpu,
59 .enqueue = (void *)nohz_tick_enqueue,
60 .running = (void *)nohz_tick_running,
61 .tick = (void *)nohz_tick_tick,
62 .exit = (void *)nohz_tick_exit,
63 .name = "nohz_tick",
64 .timeout_ms = 1000U,
65 };
66