dsp_local_on.bpf.c

 1/* SPDX-License-Identifier: GPL-2.0 */
 2/*
 3 * Copyright (c) 2024 Meta Platforms, Inc. and affiliates.
 4 * Copyright (c) 2024 David Vernet <dvernet@meta.com>
 5 */
 6#include <scx/common.bpf.h>
 7
 8char _license[] SEC("license") = "GPL";
 9const volatile s32 nr_cpus;
10
11UEI_DEFINE(uei);
12
13struct {
14	__uint(type, BPF_MAP_TYPE_QUEUE);
15	__uint(max_entries, 8192);
16	__type(value, s32);
17} queue SEC(".maps");
18
19s32 BPF_STRUCT_OPS(dsp_local_on_select_cpu, struct task_struct *p,
20		   s32 prev_cpu, u64 wake_flags)
21{
22	return prev_cpu;
23}
24
25void BPF_STRUCT_OPS(dsp_local_on_enqueue, struct task_struct *p,
26		    u64 enq_flags)
27{
28	s32 pid = p->pid;
29
30	if (bpf_map_push_elem(&queue, &pid, 0))
31		scx_bpf_error("Failed to enqueue %s[%d]", p->comm, p->pid);
32}
33
34void BPF_STRUCT_OPS(dsp_local_on_dispatch, s32 cpu, struct task_struct *prev)
35{
36	s32 pid, target;
37	struct task_struct *p;
38
39	if (bpf_map_pop_elem(&queue, &pid))
40		return;
41
42	p = bpf_task_from_pid(pid);
43	if (!p)
44		return;
45
46	if (p->nr_cpus_allowed == nr_cpus && !is_migration_disabled(p))
47		target = bpf_get_prandom_u32() % nr_cpus;
48	else
49		target = scx_bpf_task_cpu(p);
50
51	scx_bpf_dsq_insert(p, SCX_DSQ_LOCAL_ON | target, SCX_SLICE_DFL, 0);
52	bpf_task_release(p);
53}
54
55void BPF_STRUCT_OPS(dsp_local_on_exit, struct scx_exit_info *ei)
56{
57	UEI_RECORD(uei, ei);
58}
59
60SEC(".struct_ops.link")
61struct sched_ext_ops dsp_local_on_ops = {
62	.select_cpu		= (void *) dsp_local_on_select_cpu,
63	.enqueue		= (void *) dsp_local_on_enqueue,
64	.dispatch		= (void *) dsp_local_on_dispatch,
65	.exit			= (void *) dsp_local_on_exit,
66	.name			= "dsp_local_on",
67	.timeout_ms		= 1000U,
68};