1 files changed, 73 insertions, 0 deletions
diff --git a/tools/testing/selftests/sched_ext/select_cpu_dispatch.c b/tools/testing/selftests/sched_ext/select_cpu_dispatch.c
new file mode 100644
index 000000000000..80283dbc41b7
--- /dev/null
+++ b/tools/testing/selftests/sched_ext/select_cpu_dispatch.c
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * 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 <bpf/bpf.h>
+#include <scx/common.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include "select_cpu_dispatch.bpf.skel.h"
+#include "scx_test.h"
+
+#define NUM_CHILDREN 1028
+
+static enum scx_test_status setup(void **ctx)
+{
+	struct select_cpu_dispatch *skel;
+
+	skel = select_cpu_dispatch__open();
+	SCX_FAIL_IF(!skel, "Failed to open");
+	SCX_ENUM_INIT(skel);
+	SCX_FAIL_IF(select_cpu_dispatch__load(skel), "Failed to load skel");
+
+	*ctx = skel;
+
+	return SCX_TEST_PASS;
+}
+
+static enum scx_test_status run(void *ctx)
+{
+	struct select_cpu_dispatch *skel = ctx;
+	struct bpf_link *link;
+	pid_t pids[NUM_CHILDREN];
+	int i, status;
+
+	link = bpf_map__attach_struct_ops(skel->maps.select_cpu_dispatch_ops);
+	SCX_FAIL_IF(!link, "Failed to attach scheduler");
+
+	for (i = 0; i < NUM_CHILDREN; i++) {
+		pids[i] = fork();
+		if (pids[i] == 0) {
+			sleep(1);
+			exit(0);
+		}
+	}
+
+	for (i = 0; i < NUM_CHILDREN; i++) {
+		SCX_EQ(waitpid(pids[i], &status, 0), pids[i]);
+		SCX_EQ(status, 0);
+	}
+
+	bpf_link__destroy(link);
+
+	return SCX_TEST_PASS;
+}
+
+static void cleanup(void *ctx)
+{
+	struct select_cpu_dispatch *skel = ctx;
+
+	select_cpu_dispatch__destroy(skel);
+}
+
+struct scx_test select_cpu_dispatch = {
+	.name = "select_cpu_dispatch",
+	.description = "Test direct dispatching to built-in DSQs from "
+		       "ops.select_cpu()",
+	.setup = setup,
+	.run = run,
+	.cleanup = cleanup,
+};
+REGISTER_SCX_TEST(&select_cpu_dispatch)