1 files changed, 41 insertions, 0 deletions
diff --git a/tools/testing/selftests/sched_ext/select_cpu_dispatch.bpf.c b/tools/testing/selftests/sched_ext/select_cpu_dispatch.bpf.c
new file mode 100644
index 000000000000..4bb99699e920
--- /dev/null
+++ b/tools/testing/selftests/sched_ext/select_cpu_dispatch.bpf.c
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * A scheduler that validates the behavior of direct dispatching with a default
+ * select_cpu implementation.
+ *
+ * Copyright (c) 2023 Meta Platforms, Inc. and affiliates.
+ * Copyright (c) 2023 David Vernet <dvernet@meta.com>
+ * Copyright (c) 2023 Tejun Heo <tj@kernel.org>
+ */
+
+#include <scx/common.bpf.h>
+
+char _license[] SEC("license") = "GPL";
+
+s32 BPF_STRUCT_OPS(select_cpu_dispatch_select_cpu, struct task_struct *p,
+		   s32 prev_cpu, u64 wake_flags)
+{
+	u64 dsq_id = SCX_DSQ_LOCAL;
+	s32 cpu = prev_cpu;
+
+	if (scx_bpf_test_and_clear_cpu_idle(cpu))
+		goto dispatch;
+
+	cpu = scx_bpf_pick_idle_cpu(p->cpus_ptr, 0);
+	if (cpu >= 0)
+		goto dispatch;
+
+	dsq_id = SCX_DSQ_GLOBAL;
+	cpu = prev_cpu;
+
+dispatch:
+	scx_bpf_dsq_insert(p, dsq_id, SCX_SLICE_DFL, 0);
+	return cpu;
+}
+
+SEC(".struct_ops.link")
+struct sched_ext_ops select_cpu_dispatch_ops = {
+	.select_cpu		= (void *) select_cpu_dispatch_select_cpu,
+	.name			= "select_cpu_dispatch",
+	.timeout_ms		= 1000U,
+};