Quelle  enq_select_cpu.bpf.c   Sprache: C

// 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 <scx/common.bpf.h>

char _license[] SEC("license") = "GPL";

UEI_DEFINE(uei);

s32 BPF_STRUCT_OPS(enq_select_cpu_select_cpu, struct task_struct *p,
     s32 prev_cpu, u64 wake_flags)
{
 /* Bounce all tasks to ops.enqueue() */
 return prev_cpu;
}

void BPF_STRUCT_OPS(enq_select_cpu_enqueue, struct task_struct *p,
      u64 enq_flags)
{
 s32 cpu, prev_cpu = scx_bpf_task_cpu(p);
 bool found = false;

 cpu = scx_bpf_select_cpu_dfl(p, prev_cpu, 0, &found);
 if (found) {
  scx_bpf_dsq_insert(p, SCX_DSQ_LOCAL_ON | cpu, SCX_SLICE_DFL, enq_flags);
  return;
 }

 scx_bpf_dsq_insert(p, SCX_DSQ_GLOBAL, SCX_SLICE_DFL, enq_flags);
}

void BPF_STRUCT_OPS(enq_select_cpu_exit, struct scx_exit_info *ei)
{
 UEI_RECORD(uei, ei);
}

struct task_cpu_arg {
 pid_t pid;
};

SEC("syscall")
int select_cpu_from_user(struct task_cpu_arg *input)
{
 struct task_struct *p;
 bool found = false;
 s32 cpu;

 p = bpf_task_from_pid(input->pid);
 if (!p)
  return -EINVAL;

 bpf_rcu_read_lock();
 cpu = scx_bpf_select_cpu_dfl(p, bpf_get_smp_processor_id(), 0, &found);
 if (!found)
  cpu = -EBUSY;
 bpf_rcu_read_unlock();

 bpf_task_release(p);

 return cpu;
}

SEC(".struct_ops.link")
struct sched_ext_ops enq_select_cpu_ops = {
 .select_cpu  = (void *)enq_select_cpu_select_cpu,
 .enqueue  = (void *)enq_select_cpu_enqueue,
 .exit   = (void *)enq_select_cpu_exit,
 .name   = "enq_select_cpu",
 .timeout_ms  = 1000U,
};