1 files changed, 108 insertions, 0 deletions
diff --git a/tools/testing/selftests/sched_ext/nohz_tick.bpf.c b/tools/testing/selftests/sched_ext/nohz_tick.bpf.c
new file mode 100644
index 000000000000..5fec5673fbf2
--- /dev/null
+++ b/tools/testing/selftests/sched_ext/nohz_tick.bpf.c
@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES
+ *
+ * Exercise tick dependency transitions between infinite and finite slices.
+ */
+#include <scx/common.bpf.h>
+
+#include "nohz_tick_test.h"
+
+char _license[] SEC("license") = "GPL";
+
+const volatile s32 test_cpu;
+u32 phase;
+s32 victim_pid;
+s32 challenger_pid;
+s32 trigger_pid;
+u64 nr_inf_running;
+u64 nr_finite_running;
+u64 nr_finite_ticks;
+u64 nr_lazy_victim_running;
+u64 nr_lazy_enq_running;
+u64 nr_lazy_kick_running;
+u64 nr_lazy_ticks;
+
+UEI_DEFINE(uei);
+
+s32 BPF_STRUCT_OPS(nohz_tick_select_cpu, struct task_struct *p, s32 prev_cpu,
+		   u64 wake_flags)
+{
+	return prev_cpu;
+}
+
+void BPF_STRUCT_OPS(nohz_tick_enqueue, struct task_struct *p, u64 enq_flags)
+{
+	u64 slice;
+	u64 dsq_id = SCX_DSQ_GLOBAL;
+
+	switch (phase) {
+	case NOHZ_PHASE_INF:
+		slice = SCX_SLICE_INF;
+		break;
+	case NOHZ_PHASE_FINITE:
+		slice = 1000000ULL;
+		break;
+	case NOHZ_PHASE_LAZY_ENQ:
+	case NOHZ_PHASE_LAZY_KICK:
+		dsq_id = SCX_DSQ_LOCAL;
+		slice = p->pid == victim_pid ? SCX_SLICE_INF : SCX_SLICE_DFL;
+		if (phase == NOHZ_PHASE_LAZY_ENQ && p->pid == challenger_pid)
+			enq_flags |= SCX_ENQ_PREEMPT_LAZY;
+		break;
+	default:
+		slice = SCX_SLICE_DFL;
+		break;
+	}
+
+	scx_bpf_dsq_insert(p, dsq_id, slice, enq_flags);
+	if (phase == NOHZ_PHASE_LAZY_KICK && p->pid == trigger_pid)
+		scx_bpf_kick_cpu(test_cpu, SCX_KICK_PREEMPT_LAZY);
+	if (enq_flags & SCX_ENQ_LAST)
+		scx_bpf_kick_cpu(test_cpu, SCX_KICK_IDLE);
+}
+
+void BPF_STRUCT_OPS(nohz_tick_running, struct task_struct *p)
+{
+	if (bpf_get_smp_processor_id() != test_cpu)
+		return;
+
+	if (phase == NOHZ_PHASE_FINITE)
+		__sync_fetch_and_add(&nr_finite_running, 1);
+	else if (phase == NOHZ_PHASE_INF)
+		__sync_fetch_and_add(&nr_inf_running, 1);
+	else if (p->pid == victim_pid)
+		__sync_fetch_and_add(&nr_lazy_victim_running, 1);
+	else if (phase == NOHZ_PHASE_LAZY_ENQ && p->pid == challenger_pid)
+		__sync_fetch_and_add(&nr_lazy_enq_running, 1);
+	else if (phase == NOHZ_PHASE_LAZY_KICK && p->pid == challenger_pid)
+		__sync_fetch_and_add(&nr_lazy_kick_running, 1);
+}
+
+void BPF_STRUCT_OPS(nohz_tick_tick, struct task_struct *p)
+{
+	if (bpf_get_smp_processor_id() != test_cpu)
+		return;
+
+	if (phase == NOHZ_PHASE_FINITE)
+		__sync_fetch_and_add(&nr_finite_ticks, 1);
+	else if ((phase == NOHZ_PHASE_LAZY_ENQ ||
+		  phase == NOHZ_PHASE_LAZY_KICK) && p->pid == victim_pid)
+		__sync_fetch_and_add(&nr_lazy_ticks, 1);
+}
+
+void BPF_STRUCT_OPS(nohz_tick_exit, struct scx_exit_info *ei)
+{
+	UEI_RECORD(uei, ei);
+}
+
+SEC(".struct_ops.link")
+struct sched_ext_ops nohz_tick_ops = {
+	.select_cpu		= (void *)nohz_tick_select_cpu,
+	.enqueue		= (void *)nohz_tick_enqueue,
+	.running		= (void *)nohz_tick_running,
+	.tick			= (void *)nohz_tick_tick,
+	.exit			= (void *)nohz_tick_exit,
+	.name			= "nohz_tick",
+	.timeout_ms		= 5000U,
+};