1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * A scheduler that validates the behavior of direct dispatching with a default
4 * select_cpu implementation.
5 *
6 * Copyright (c) 2023 Meta Platforms, Inc. and affiliates.
7 * Copyright (c) 2023 David Vernet <dvernet@meta.com>
8 * Copyright (c) 2023 Tejun Heo <tj@kernel.org>
9 */
10
11 #include <scx/common.bpf.h>
12
13 char _license[] SEC("license") = "GPL";
14
15 s32 BPF_STRUCT_OPS(select_cpu_dispatch_select_cpu, struct task_struct *p,
16 s32 prev_cpu, u64 wake_flags)
17 {
18 u64 dsq_id = SCX_DSQ_LOCAL;
19 s32 cpu = prev_cpu;
20
21 if (scx_bpf_test_and_clear_cpu_idle(cpu))
22 goto dispatch;
23
24 cpu = scx_bpf_pick_idle_cpu(p->cpus_ptr, 0);
25 if (cpu >= 0)
26 goto dispatch;
27
28 dsq_id = SCX_DSQ_GLOBAL;
29 cpu = prev_cpu;
30
31 dispatch:
32 scx_bpf_dispatch(p, dsq_id, SCX_SLICE_DFL, 0);
33 return cpu;
34 }
35
36 SEC(".struct_ops.link")
37 struct sched_ext_ops select_cpu_dispatch_ops = {
38 .select_cpu = (void *) select_cpu_dispatch_select_cpu,
39 .name = "select_cpu_dispatch",
40 .timeout_ms = 1000U,
41 };
42
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